Articoli di riviste: "Synthèse de peptides"

1

Kraus, Jean Louis. "Synthèse d'azamacrocycles polysubstitués par des peptides biologiquement actifs". Journal of Heterocyclic Chemistry 22, n. 5 (settembre 1985): 1307–12. http://dx.doi.org/10.1002/jhet.5570220532.

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Duvallet, Emilie, Mathilde Boulpicante e Sébastien Apcher. "Synthèse des peptides antigéniques du CMH-I dans le noyau". médecine/sciences 30, n. 3 (marzo 2014): 229–31. http://dx.doi.org/10.1051/medsci/20143003002.

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LE FLOC’H, N., e B. SEVE. "Le devenir des protéines et des acides aminés dans l’intestin du porc : de la digestion à l’apparition dans la veine porte". INRAE Productions Animales 13, n. 5 (22 ottobre 2000): 303–14. http://dx.doi.org/10.20870/productions-animales.2000.13.5.3798.

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La digestion intestinale des protéines alimentaires fait intervenir des protéases d’origine pancréatique et des peptidases intestinales. Les produits de la digestion sont constitués d’acides aminés libres et de peptides relativement abondants. Acides aminés et peptides sont transportés dans l’entérocyte où ces derniers subissent une hydrolyse. Les acides aminés libres présents dans la veine porte présentent un profil bien différent de celui des protéines alimentaires. En effet, le métabolisme intestinal des acides aminés est très actif. Afin d’assurer la synthèse des protéines constitutives et sécrétées, l’intestin prélève des acides aminés à la fois dans la lumière intestinale et dans le sang artériel. Cet organe renouvelle plus de 50 % de ses protéines par jour et la synthèse de protéines bien particulières comme les mucines engendre des besoins élevés en certains acides aminés comme la thréonine. L’intestin est le principal tissu utilisant la glutamine artérielle et le glutamate alimentaire. Le catabolisme intestinal de ces acides aminés produit de l’alanine, de l’acide aspartique, de la proline et, par l’intermédiaire des enzymes du cycle de l’urée, de l’ornithine, de la citrulline et de l’arginine. Les acides aminés indispensables n’échapperaient pas non plus au catabolisme intestinal. Le rôle de l’intestin ne se limite donc pas à la digestion des protéines et à l’absorption des acides aminés. Son métabolisme modifie profondément la disponibilité des acides aminés alimentaires pour le reste de l’organisme.

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Salvadori, S. "Peptides opioides: synthèse et propriétés biologiques d'hexapeptides apparents à la dermorphine". European Journal of Medicinal Chemistry 25, n. 2 (marzo 1990): 171–77. http://dx.doi.org/10.1016/0223-5234(90)90025-x.

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5

Rousseau, F., V. Fuentes, C. Corbel, E. Bissac, F. Eb e J. Orfila. "Intérêt des peptides de synthèse dans le sérodiagnostic d'infections à Chlamydia". La Revue de Médecine Interne 17 (gennaio 1995): S107. http://dx.doi.org/10.1016/0248-8663(96)86610-0.

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6

Michel, Andre G., Chakib Ameziane-Hassani, Gaston Boulay e Gilles Lajoie. "Étude structurale de la liaison thioamide: Synthèse et conformation de dérivés de la thioalanine et de la thioglycine". Canadian Journal of Chemistry 67, n. 8 (1 agosto 1989): 1312–18. http://dx.doi.org/10.1139/v89-202.

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The present study reports the synthesis, crystal structure determinations, and the conformational analysis of N-tertiobutyloxycarbonyl N′-methylthioalanine (Boc-AlaS-NHCH3, C9H18N2O2S) and of N-tertiobutyloxycarbonyl N′-methylthioglycine (Boc-GlyS-NHCH3, C8H16N2O2S). The particular feature of these compounds is the replacement of the classical oxopeptide linkage by a thioamide bond. Crystals of Boc-AlaS-NHCH3 are tetragonal, space group P43212. Those of Boc-GlyS-NHCH3 are monoclinic, space group P21/c. Both structures were solved by direct methods and refined by full-matrix least-squares methods to Rw = 0.045 and 0.035 for 827 and 1335 reflections respectively, with intensities greater than 2.5σ(I). The conformations of both compounds correspond to conformational energy minima, calculated for classical amino acids. The C=S bond lengths of 1.665(9) and 1.650(3) Å constitute the major difference compared to oxopeptides; the crystal structures reveal that the presence of the sulfur atom does not change the electronic properties of the peptide bond. Using a classical method for the study of peptides (ECEPP/2), conformational energy maps were computed for derivatives of dithioalanine and dithioglycine and are compared to the oxo residues. We conclude that the synthesis and conformational analysis of thionated amino acids allow us to introduce the thioamide linkage into more complex peptide structures and to predict the conformational behaviour. Keywords: molecular conformations, peptidic structure, crystallography.

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Collet, C., S. Lamandé-Langle, F. Chrétien, F. Maskali, S. Poussier, P. Y. Marie, G. Karcher e Y. Chapleur. "Synthèse de nouveaux [18F]fluoro-sucres pour le radiomarquage de peptides : application en imagerie TEP". Médecine Nucléaire 38, n. 3 (maggio 2014): 159. http://dx.doi.org/10.1016/j.mednuc.2014.03.115.

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Zineddine, H., M. Asso, R. Panossian, M. Guiliano e D. Benlian. "Synthèse et structure de complexes d'ions métalliques et de peptides à résidus aspartyl et tyrosyl". Journal of Molecular Structure 192, n. 1-2 (gennaio 1989): 95–106. http://dx.doi.org/10.1016/0022-2860(89)87009-7.

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Ruzycki, Shannon Marie, e Michael Prystajecky. "Point-Counterpoint: Perioperative Cardiac Biomarkers". Canadian Journal of General Internal Medicine 14, n. 4 (19 novembre 2019): e14-e22. http://dx.doi.org/10.22374/cjgim.v14i4.347.

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In the following review article, we present arguments for and against the use of postoperative troponin surveillance and preoperative natriuretic peptide testing. This article covers the evidence that informed the CCS 2016 perioperative guidelines and research published since then. This review is based on the debate held at the Canadian Society of Internal Medicine/American College of Physicians Rocky Mountain Chapter Annual Meeting (CSIM/ACP RM) held in October 2018 in Banff, Alberta. Resume Dans l'article de synthèse qui suit, nous présentons des arguments pour et contre l'utilisation de la surveillance postopératoire de la troponine et des tests préopératoires de peptides natriurétiques. Cet article porte sur les données probantes qui ont éclairé les lignes directrices périopératoires de la SCC 2016 et les recherches publiées depuis lors. Cet examen est fondé sur le débat qui a eu lieu à l'assemblée annuelle de la section des Rocheuses de la Société canadienne de médecine interne et de l'American College of Physicians (CSIM/ACP RM) tenue en octobre 2018 à Banff, en Alberta.

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Rauscher, A., P. Baumgartner, F. Lacoeuille, A. Cahouet-Vannier, C. Ansquer, C. Rousseau, F. Kraeber-Bodéré e A. Faivre-Chauvet. "Comparaison de deux techniques de pré-purification des éluats de 68GA pour le marquage de peptides par automate de synthèse". Médecine Nucléaire 38, n. 3 (maggio 2014): 160–61. http://dx.doi.org/10.1016/j.mednuc.2014.03.120.

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Betsou, F., JM Sueur, C. Chaigneau, A. Gommeaux e J. Orfila. "Des corps élémentaires aux peptides de synthèse : comparaison de techniques sérologiques utilisées pour la détection des anticorps spécifiques de Chlamydia trachomatis et Chlamydia pneumoniae". Immuno-analyse & Biologie Spécialisée 16, n. 1 (gennaio 2001): 40–46. http://dx.doi.org/10.1016/s0923-2532(01)80008-9.

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12

LECLERC, Estelle, Chantal CORTI, Holger SCHMID, Stefan VETTER, Peter JAMES e Ernesto CARAFOLI. "Serine/threonine phosphorylation of calmodulin modulates its interaction with the binding domains of target enzymes". Biochemical Journal 344, n. 2 (24 novembre 1999): 403–11. http://dx.doi.org/10.1042/bj3440403.

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The interaction of serine/threonine-phosphorylated calmodulin with synthetic peptides corresponding to the calmodulin-binding domains of six enzymes has been studied by fluorescence spectroscopy. For five peptides, the dissociation constant of the calmodulin-peptide complex (Kd) increased when calmodulin was phosphorylated. An increase of more than one order of magnitude was observed with peptides derived from smooth-muscle myosin light-chain kinase and cAMP phosphodiesterase. In contrast, only a slight increase in Kd was noted with two peptides derived from the plasma membrane Ca2+-ATPase and for the peptide derived from nitric oxide synthase. No significant change in affinity was detected with the peptide derived from calcineurin. In contrast, a decrease in the dissociation constant was observed with the peptide derived from the Ca2+-calmodulin dependent kinase II. Phosphorylation also affected the peptide-calmodulin binding stoichiometry: a decrease from two to one binding sites was observed with the peptides derived from myosin light-chain kinase and phosphodiesterase.

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13

Harken, Lauritz, e Shu-Ming Li. "Modifications of diketopiperazines assembled by cyclodipeptide synthases with cytochrome P450 enzymes". Applied Microbiology and Biotechnology 105, n. 6 (24 febbraio 2021): 2277–85. http://dx.doi.org/10.1007/s00253-021-11178-1.

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Abstract2,5-Diketopiperazines are the smallest cyclic peptides comprising two amino acids connected via two peptide bonds. They can be biosynthesized in nature by two different enzyme families, either by nonribosomal peptide synthetases or by cyclodipeptide synthases. Due to the stable scaffold of the diketopiperazine ring, they can serve as precursors for further modifications by different tailoring enzymes, such as methyltransferases, prenyltransferases, oxidoreductases like cyclodipeptide oxidases, 2-oxoglutarate-dependent monooxygenases and cytochrome P450 enzymes, leading to the formation of intriguing secondary metabolites. Among them, cyclodipeptide synthase-associated P450s attracted recently significant attention, since they are able to catalyse a broader variety of astonishing reactions than just oxidation by insertion of an oxygen. The P450-catalysed reactions include hydroxylation at a tertiary carbon, aromatisation of the diketopiperazine ring, intramolecular and intermolecular carbon-carbon and carbon-nitrogen bond formation of cyclodipeptides and nucleobase transfer reactions. Elucidation of the crystal structures of three P450s as cyclodipeptide dimerases provides a structural basis for understanding the reaction mechanism and generating new enzymes by protein engineering. This review summarises recent publications on cyclodipeptide modifications by P450s.Key Points• Intriguing reactions catalysed by cyclodipeptide synthase-associated cytochrome P450s• Homo- and heterodimerisation of diketopiperazines• Coupling of guanine and hypoxanthine with diketopiperazines Graphical abstract

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14

Nguyen, Tiffany T., Mourad Ogbi, Qilin Yu e John A. Johnson. "Attenuation of the hypoxia-induced protein kinase Cδ interaction with the ‘d’ subunit of F1Fo-ATP synthase in neonatal cardiac myocytes: implications for energy preservation and survival". Biochemical Journal 429, n. 2 (28 giugno 2010): 335–45. http://dx.doi.org/10.1042/bj20091927.

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The F1Fo-ATP synthase provides most of the heart's energy, yet events that alter its function during injury are poorly understood. Recently, we described a potent inhibitory effect on F1Fo-ATP synthase function mediated by the interaction of PKCδ (protein kinase Cδ) with dF1Fo (‘d’ subunit of the F1Fo-ATPase/ATP synthase). We have now developed novel peptide modulators which facilitate or inhibit the PKCδ–dF1Fo interaction. These peptides include HIV-Tat (transactivator of transcription) protein transduction and mammalian mitochondrial-targeting sequences. Pre-incubation of NCMs (neonatal cardiac myocyte) with 10 nM extracellular concentrations of the mitochondrial-targeted PKCδ–dF1Fo interaction inhibitor decreased Hx (hypoxia)-induced co-IP (co-immunoprecipitation) of PKCδ with dF1Fo by 40±9%, abolished Hx-induced inhibition of F1Fo-ATPase activity, attenuated Hx-induced losses in F1Fo-derived ATP and protected against Hx- and reperfusion-induced cell death. A scrambled-sequence (inactive) peptide, which contained HIV-Tat and mitochondrial-targeting sequences, was without effect. In contrast, the cell-permeant mitochondrial-targeted PKCδ–dF1Fo facilitator peptide, which we have shown previously to induce the PKCδ–dF1Fo co-IP, was found to inhibit F1Fo-ATPase activity to an extent similar to that caused by Hx alone. The PKCδ–dF1Fo facilitator peptide also decreased ATP levels by 72±18% under hypoxic conditions in the presence of glycolytic inhibition. None of the PKCδ–dF1Fo modulatory peptides altered the inner mitochondrial membrane potential. Our studies provide the first evidence that disruption of the PKCδ–dF1Fo interaction using cell-permeant mitochondrial-targeted peptides attenuates cardiac injury resulting from prolonged oxygen deprivation.

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CHILD, J. Christopher, e Peter M. SHOOLINGIN-JORDAN. "Inactivation of the polyketide synthase, 6-methylsalicylic acid synthase, by the specific modification of Cys-204 of the β-ketoacyl synthase by the fungal mycotoxin cerulenin". Biochemical Journal 330, n. 2 (1 marzo 1998): 933–37. http://dx.doi.org/10.1042/bj3300933.

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Cerulenin, [(2S,3R)-2,3-epoxy-4-oxo-7,10-dodecadienoylamide], a mycotoxin produced by Cephalosporium caerulens, irreversibly inactivated 6-methylsalicylic acid synthase from Penicillium patulum. A combination of radiolabelling studies with [3H]cerulenin, proteolytic and chemical digestion and N-terminal sequencing of labelled peptides indicated that the site of cerulenin modification is the highly reactive substrate-binding Cys-204 of the β-ketoacyl synthase enzyme component. The thiol-specific inhibitor, iodoacetamide, was also shown to alkylate this residue. These findings are analogous with those observed for the reaction of cerulenin and iodoacetamide with type-I fatty acid synthases, demonstrating the close similarity between 6-methylsalicylic acid synthase and type-I fatty acid synthases.

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ELOIT, M. "Vaccins traditionnels et vaccins recombinants". INRAE Productions Animales 11, n. 1 (1 febbraio 1998): 5–13. http://dx.doi.org/10.20870/productions-animales.1998.11.1.3912.

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Différents types de vaccins sont actuellement disponibles ou en cours de développement. Ils peuvent être divisés en deux catégories : vaccins vivants et vaccins inertes. Les vaccins vivants traditionnels incluent des souches atténuées par des moyens conventionnels, comme la croissance dans des conditions de culture inhabituelles (bactéries), ou dans des cellules ou des animaux vis-à-vis desquels les souches ne sont pas initialement adaptées (virus). Les nouvelles générations de vaccins vivants utilisant les techniques de recombinaison génétique (vaccins recombinants) peuvent être fabriquées par mutagénèse dirigée de gènes de virulence, ou par clonage de gènes de protéines immunogènes dans des vecteurs viraux ou bactériens qui possèdent les propriétés souhaitées d’innocuité et d’efficacité. Les vaccins inactivés conventionnels sont fabriqués par traitement des microorganismes par des agents physiques ou chimiques. Dans la mesure où les fractions immunogènes des microorganismes sont de mieux en mieux connues, elles peuvent être utilisées pour fabriquer des vaccins ne comprenant que ces fractions immunogènes majeures (vaccin subunitaires) par purification, ou par expressionin vitro de protéines (un autre type de vaccin recombinant) ou enfin synthèse chimique de peptides. Récemment, il a été démontré, chez différentes espèces, que l’inoculation directe dans le muscle d’un gène codant pour une protéine immunogène (immunisation génétique) permettait d’induire une réponse immune cellulaire et humorale. Cette méthode correspond à un dernier type de vaccin recombinant. L’immunité systémique et muqueuse obtenue après injection de vaccin vivant est comparée à celle obtenue après injection de vaccin inerte.

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Jackerott, Malene, e Lars-Inge Larsson. "Immunocytochemical Localization of the NPY/PYY Y1 Receptor in Enteric Neurons, Endothelial Cells, and Endocrine-like Cells of the Rat Intestinal Tract". Journal of Histochemistry & Cytochemistry 45, n. 12 (dicembre 1997): 1643–50. http://dx.doi.org/10.1177/002215549704501207.

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Neuropeptide Y (NPY) and peptide YY (PYY) are structurally related peptides that are considered to mediate inhibitory actions on gastrointestinal motility, secretion, and blood flow. Several receptor subtypes for these peptides have been identified and the Y1, Y2, Y4/PP1, Y5, and Y5/PP2/Y2b receptors have been cloned. In this article we report the immunocytochemical localization of the Y1 receptor to myenteric and submucosal nerve cell bodies, endothelial cells, and scattered endocrine-like cells of rat intestinal tract. Moreover, double immunofluorescence demonstrates that subpopulations of the Y1 receptor-positive nerve cell bodies are immunopositive for NPY, vasoactive intestinal polypeptide, and nitric oxide synthase. In part, such co-localizations were made possible by use of peroxidase-mediated deposition of tyramide, which permitted use of antisera derived from the same species. Our observations suggest the existence of multiple neuronal, endothelial, and endocrine target sites for NPY and PYY and that some of the actions of these regulatory peptides can be mediated by vasoactive intestinal peptide and nitric oxide synthase.

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Bergeron, Lindsay H., Jordan M. Willcox, Faisal J. Alibhai, Barry J. Connell, Tarek M. Saleh, Brian C. Wilson e Alastair J. S. Summerlee. "Relaxin Peptide Hormones Are Protective During the Early Stages of Ischemic Stroke in Male Rats". Endocrinology 156, n. 2 (2 dicembre 2014): 638–46. http://dx.doi.org/10.1210/en.2014-1676.

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The pregnancy hormone relaxin protects tissue from ischemic damage. The ability of relaxin-3, a relaxin paralog, to do so has not been explored. The cerebral expression levels of these peptides and their receptors make them logical targets for study in the ischemic brain. We assessed relaxin peptide-mediated protection, relative relaxin family peptide receptor (RXFP) involvement, and protective mechanisms. Sprague-Dawley rats receiving permanent (pMCAO) or transient middle cerebral artery occlusions (tMCAO) were treated with relaxin peptides, and brains were collected for infarct analysis. Activation of the endothelial nitric oxide synthase pathway was evaluated as a potential protective mechanism. Primary cortical rat astrocytes were exposed to oxygen glucose deprivation and treated with relaxin peptides, and viability was examined. Receptor involvement was explored using RXFP3 antagonist or agonist treatment and real-time PCR. Relaxin and relaxin-3 reduced infarct size after pMCAO. Both peptides activated endothelial nitric oxide synthase. Because relaxin-3 has not previously been associated with this pathway and displays promiscuous RXFP binding, we explored the receptor contribution. Expression of rxfp1 was greater than that of rxfp3 in rat brain, although peptide binding at either receptor resulted in similar overall protection after pMCAO. Only RXFP3 activation reduced infarct size after tMCAO. In astrocytes, rxfp3 gene expression was greater than that of rxfp1. Selective activation of RXFP3 maintained astrocyte viability after oxygen glucose deprivation. Relaxin peptides are protective during the early stages of ischemic stroke. Differential responses among treatments and models suggest that RXFP1 and RXFP3 initiate different protective mechanisms. This preliminary work is a pivotal first step in identifying the clinical implications of relaxin peptides in ischemic stroke.

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Kang, Taek Jin, e Hiroaki Suga. "Ribosomal synthesis of nonstandard peptidesThis paper is one of a selection of papers published in this Special Issue, entitled CSBMCB — Systems and Chemical Biology, and has undergone the Journal's usual peer review process." Biochemistry and Cell Biology 86, n. 2 (aprile 2008): 92–99. http://dx.doi.org/10.1139/o08-009.

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It is well known that standard peptides, which comprise proteinogenic amino acids, can act as specific chemical probes to target proteins with high affinity. Despite this fact, a number of peptide drug leads have been abandoned because of their poor cell permeability and protease instability. On the other hand, nonstandard peptides isolated as natural products often exhibit remarkable pharmaco-behavior and stability in vivo. Although it is likely that numerous nonstandard therapeutic peptides capable of recognizing various targets could have been synthesized, enzymes for nonribosomal peptide syntheses are complex; therefore, it is difficult to engineer such modular enzymes to build nonstandard peptide libraries. Here we describe an emerging technology for the synthesis of nonstandard peptides that employs an integrated system of reconstituted cell-free translation and flexizymes. We summarize the historical background of this technology and discuss its current and future applications to the synthesis of nonstandard peptides and drug discovery.

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Servatius, Phil, Lukas Junk e Uli Kazmaier. "Peptide Modifications: Versatile Tools in Peptide and Natural Product Syntheses". Synlett 30, n. 11 (2 aprile 2019): 1289–302. http://dx.doi.org/10.1055/s-0037-1612417.

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Peptide modifications via C–C bond formation have emerged as valuable tools for the preparation and alteration of non-proteinogenic amino acids and the corresponding peptides. Modification of glycine subunits in peptides allows for the incorporation of unusual side chains, often in a highly stereoselective manner, orchestrated by the chiral peptide backbone. Moreover, modifications of peptides are not limited to the peptidic backbone. Many side-chain modifications, not only by variation of existing functional groups, but also by C–H functionalization, have been developed over the past decade. This account highlights the synthetic contributions made by our group and others to the field of peptide modifications and their application in natural product syntheses.1 Introduction2 Peptide Backbone Modifications via Peptide Enolates2.1 Chelate Enolate Claisen Rearrangements2.2 Allylic Alkylations2.3 Miscellaneous Modifications3 Side-Chain Modifications3.1 C–H Activation3.1.1 Functionalization via Csp3–H Bond Activation3.2.2 Functionalization via Csp2–H Bond Activation3.2 On Peptide Tryptophan Syntheses4 Conclusion

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Planas, Raquel, Radleigh Santos, Paula Tomas-Ojer, Carolina Cruciani, Andreas Lutterotti, Wolfgang Faigle, Nicole Schaeren-Wiemers et al. "GDP-l-fucose synthase is a CD4+ T cell–specific autoantigen in DRB3*02:02 patients with multiple sclerosis". Science Translational Medicine 10, n. 462 (10 ottobre 2018): eaat4301. http://dx.doi.org/10.1126/scitranslmed.aat4301.

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Multiple sclerosis is an immune-mediated autoimmune disease of the central nervous system that develops in genetically susceptible individuals and likely requires environmental triggers. The autoantigens and molecular mimics triggering the autoimmune response in multiple sclerosis remain incompletely understood. By using a brain-infiltrating CD4+ T cell clone that is clonally expanded in multiple sclerosis brain lesions and a systematic approach for the identification of its target antigens, positional scanning peptide libraries in combination with biometrical analysis, we have identified guanosine diphosphate (GDP)–l-fucose synthase as an autoantigen that is recognized by cerebrospinal fluid–infiltrating CD4+ T cells from HLA-DRB3*–positive patients. Significant associations were found between reactivity to GDP-l-fucose synthase peptides and DRB3*02:02 expression, along with reactivity against an immunodominant myelin basic protein peptide. These results, coupled with the cross-recognition of homologous peptides from gut microbiota, suggest a possible role of this antigen as an inducer or driver of pathogenic autoimmune responses in multiple sclerosis.

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Pacifico, Salvatore, Matteo Santucci, Rosaria Luciani, Puneet Saxena, Pasquale Linciano, Glauco Ponterini, Angela Lauriola et al. "Cyclic Peptides Acting as Allosteric Inhibitors of Human Thymidylate Synthase and Cancer Cell Growth". Molecules 24, n. 19 (26 settembre 2019): 3493. http://dx.doi.org/10.3390/molecules24193493.

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Thymidylate synthase (TS) is a prominent drug target for different cancer types. However, the prolonged use of its classical inhibitors, substrate analogs that bind at the active site, leads to TS overexpression and drug resistance in the clinic. In the effort to identify anti-TS drugs with new modes of action and able to overcome platinum drug resistance in ovarian cancer, octapeptides with a new allosteric inhibition mechanism were identified as cancer cell growth inhibitors that do not cause TS overexpression. To improve the biological properties, 10 cyclic peptides (cPs) were designed from the lead peptides and synthesized. The cPs were screened for the ability to inhibit recombinant human thymidylate synthase (hTS), and peptide 7 was found to act as an allosteric inhibitor more potent than its parent open-chain peptide [Pro3]LR. In cytotoxicity studies on three human ovarian cancer cell lines, IGROV-1, A2780, and A2780/CP, peptide 5 and two other cPs, including 7, showed IC50 values comparable with those of the reference drug 5-fluorouracil, of the open-chain peptide [d-Gln4]LR, and of another seven prolyl derivatives of the lead peptide LR. These promising results indicate cP 7 as a possible lead compound to be chemically modified with the aim of improving both allosteric TS inhibitory activity and anticancer effectiveness.

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Bendlová, Běla, Michal Lebl, Pavel Štolba e Luboslav Stárka. "Synthesis of modified human C-peptide and its fragments". Collection of Czechoslovak Chemical Communications 53, n. 11 (1988): 2637–44. http://dx.doi.org/10.1135/cccc19882637.

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Syntheses of the modified human C-peptide containing residues suitable for the introduction of the radioactive label (tyrosine) and internal marker for monitoring binding to carrier (norvaline) and five of its fragments are described. The syntheses were performed by solid phase method using either 9-fluorenylmethoxycarbonyl or tert-butyloxycarbonyl protecting groups. The products were purified by gel filtration, ion exchange chromatography and reversed phase HPLC. The reactivity of prepared peptides with antisera was determined and the modified C-peptide was found fully reactive.

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Chu, Yin-Hung, Wen-Chieh Liao, Ying-Jui Ho, Chih-Hsien Huang, To-Jung Tseng e Chiung-Hui Liu. "Targeting Chondroitin Sulfate Reduces Invasiveness of Glioma Cells by Suppressing CD44 and Integrin β1 Expression". Cells 10, n. 12 (20 dicembre 2021): 3594. http://dx.doi.org/10.3390/cells10123594.

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Chondroitin sulfate (CS) is a major component of the extracellular matrix found to be abnormally accumulated in several types of cancer tissues. Previous studies have indicated that CS synthases and modification enzymes are frequently elevated in human gliomas and are associated with poor prognosis. However, the underlying mechanisms of CS in cancer progression and approaches for interrupting its functions in cancer cells remain largely unexplored. Here, we have found that CS was significantly enriched surrounding the vasculature in a subset of glioma tissues, which was akin to the perivascular niche for cancer-initiating cells. Silencing or overexpression of the major CS synthase, chondroitin sulfate synthase 1 (CHSY1), significantly regulated the glioma cell invasive phenotypes and modulated integrin expression. Furthermore, we identified CD44 as a crucial chondroitin sulfate proteoglycan (CSPG) that was modified by CHSY1 on glioma cells, and the suppression of CS formation on CD44 by silencing the CHSY1-inhibited interaction between CD44 and integrin β1 on the adhesion complex. Moreover, we tested the CS-specific binding peptide, resulting in the suppression of glioma cell mobility in a fashion similar to that observed upon the silencing of CHSY1. In addition, the peptide demonstrated significant affinity to CD44, promoted CD44 degradation, and suppressed integrin β1 expression in glioma cells. Overall, this study proposes a potential regulatory loop between CS, CD44, and integrin β1 in glioma cells, and highlights the importance of CS in CD44 stability. Furthermore, the targeting of CS by specific binding peptides has potential as a novel therapeutic strategy for glioma.

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Kohlbaua, Hans-Jürgen, Jochen Tschakert, Raed A. Al-Qawasmeh, Tanveer Ahmad Nizamì, Abdul Malik e Wolfgang Voelter. "Festphasensynthese von Muramyldipeptiden an isomeren Trialkoxybenzylamin-Harzen / Solid Phase Synthesis of Muramyl Dipeptides on Isomeric Trialkoxybenzylamine Resins". Zeitschrift für Naturforschung B 53, n. 7 (1 luglio 1998): 753–64. http://dx.doi.org/10.1515/znb-1998-0716.

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Abstract New isomeric trialkoxybenzylamine resins are developed coupling phthalimidomethyl-3,5-dimethoxyphenols to the Merrifield resin, followed by subsequent treatment with hydrazine. The generated benzylamine function allows DCC coupling w ith the carboxyl function of amino acids and peptides which are removed as amides after treatment with trifluoroacetic acid. These new trialkoxybenzylamine resins allow expeditious syntheses of peptide amides and glycopeptide amides as is demonstrated for muramyl peptides and analogues.

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26

Moolhuijzen, Paula M., Mariano Jordi Muria-Gonzalez, Robert Syme, Catherine Rawlinson, Pao Theen See, Caroline S. Moffat e Simon R. Ellwood. "Expansion and Conservation of Biosynthetic Gene Clusters in Pathogenic Pyrenophora spp." Toxins 12, n. 4 (9 aprile 2020): 242. http://dx.doi.org/10.3390/toxins12040242.

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Pyrenophora is a fungal genus responsible for a number of major cereal diseases. Although fungi produce many specialised or secondary metabolites for defence and interacting with the surrounding environment, the repertoire of specialised metabolites (SM) within Pyrenophora pathogenic species remains mostly uncharted. In this study, an in-depth comparative analysis of the P. teres f. teres, P teres f. maculata and P. tritici-repentis potential to produce SMs, based on in silico predicted biosynthetic gene clusters (BGCs), was conducted using genome assemblies from PacBio DNA reads. Conservation of BGCs between the Pyrenophora species included type I polyketide synthases, terpene synthases and the first reporting of a type III polyketide synthase in P teres f. maculata. P. teres isolates exhibited substantial expansion of non-ribosomal peptide synthases relative to P. tritici-repentis, hallmarked by the presence of tailoring cis-acting nitrogen methyltransferase domains. P. teres isolates also possessed unique non-ribosomal peptide synthase (NRPS)-indole and indole BGCs, while a P. tritici-repentis phytotoxin BGC for triticone production was absent in P. teres. These differences highlight diversification between the pathogens that reflects their different evolutionary histories, host adaption and lifestyles.

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27

Dubois, Damien, Olivier Baron, Antony Cougnoux, Julien Delmas, Nathalie Pradel, Michèle Boury, Bernadette Bouchon et al. "ClbP Is a Prototype of a Peptidase Subgroup Involved in Biosynthesis of Nonribosomal Peptides". Journal of Biological Chemistry 286, n. 41 (27 luglio 2011): 35562–70. http://dx.doi.org/10.1074/jbc.m111.221960.

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The pks genomic island of Escherichia coli encodes polyketide (PK) and nonribosomal peptide (NRP) synthases that allow assembly of a putative hybrid PK-NRP compound named colibactin that induces DNA double-strand breaks in eukaryotic cells. The pks-encoded machinery harbors an atypical essential protein, ClbP. ClbP crystal structure and mutagenesis experiments revealed a serine-active site and original structural features compatible with peptidase activity, which was detected by biochemical assays. Ten ClbP homologs were identified in silico in NRP genomic islands of closely and distantly related bacterial species. All tested ClbP homologs were able to complement a clbP-deficient E. coli mutant. ClbP is therefore a prototype of a new subfamily of extracytoplasmic peptidases probably involved in the maturation of NRP compounds. Such peptidases will be powerful tools for the manipulation of NRP biosynthetic pathways.

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28

Hughes, S. J., H. Smith e S. J. H. Ashcroft. "Characterization of Ca2+/calmodulin-dependent protein kinase in rat pancreatic islets". Biochemical Journal 289, n. 3 (1 febbraio 1993): 795–800. http://dx.doi.org/10.1042/bj2890795.

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We have attempted to identify islet Ca2+/calmodulin-dependent protein kinase (CaM kinase) by comparing its activity with purified brain CaM kinase II. Islet CaM kinase, in the presence of calmodulin and Ca2+, phosphorylated major endogenous substrates of 102, 57 and 53 kDa and also exogenous glycogen synthase; brain CaM kinase II phosphorylated glycogen synthase and peptides of 57 and 53 kDa. Alloxan (1 mM) inhibited the phosphorylation of glycogen synthase and the 102, 57 and 53 kDa islet peptides by islet CaM kinase; the phosphorylation of glycogen synthase and the 57 and 53 kDa substrates by brain CaM kinase II was also inhibited by alloxan. The Ca2+ and calmodulin-dependencies of phosphorylation of the endogenous islet substrates differed. In the presence of 400 nM calmodulin, half-maximal phosphorylation was attained at Ca2+ concentrations of 80 +/- 9, 401 +/- 61 and 459 +/- 59 nM for the 102, 57 and 53 kDa substrates respectively. In the presence of 10 microM Ca2+, half-maximal phosphorylation was attained at calmodulin concentrations of 9 +/- 2, 38 +/- 2.5 and 37 +/- 2 nM for the 102, 57 and 53 kDa substrates respectively. Differential centrifugation located the 102 kDa substrate in the post-100,000 g supernatant and the 57 and 53 kDa substrates in the particulate fraction. These data suggest that islet CaM kinase is similar to, if not identical with, brain CaM kinase II, but that phosphorylation of the endogenous 102 kDa substrate occurs by a distinct kinase which shows different sensitivities to Ca2+ and calmodulin. This kinase probably corresponds to CaM kinase III and the 102 kDa peptide to elongation factor 2 (EF-2), since the 102 kDa peptide was shown to undergo ADP-ribosylation in the presence of diphtheria toxin and NAD+.

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29

Lee, Bee-Na, Scott Kroken, David Y. T. Chou, Barbara Robbertse, O. C. Yoder e B. Gillian Turgeon. "Functional Analysis of All Nonribosomal Peptide Synthetases in Cochliobolus heterostrophus Reveals a Factor, NPS6, Involved in Virulence and Resistance to Oxidative Stress". Eukaryotic Cell 4, n. 3 (marzo 2005): 545–55. http://dx.doi.org/10.1128/ec.4.3.545-555.2005.

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ABSTRACT Nonribosomal peptides, made by nonribosomal peptide synthetases, have diverse biological activities, including roles as fungal virulence effectors. Inspection of the genome of Cochliobolus heterostrophus, a fungal pathogen of maize and a member of a genus noted for secondary metabolite production, revealed eight multimodular nonribosomal peptide synthase (NPS) genes and three monomodular NPS-like genes, one of which encodes a nonribosomal peptide synthetase/polyketide synthase hybrid enzyme presumed to be involved in synthesis of a peptide/polyketide molecule. Deletion of each NPS gene and phenotypic analyses showed that the product of only one of these genes, NPS6, is required for normal virulence on maize. NPS6 is also required for resistance to hydrogen peroxide, suggesting it may protect the fungus from oxidative stress. This and all other nps mutants had normal growth, mating ability, and appressoria. Real-time PCR analysis showed that expression of all NPS genes is low (relative to that of actin), that all (except possibly NPS2) are expressed during vegetative growth, and that expression is induced by nitrogen starvation. Only NPS6 is unfailingly conserved among euascomycete fungi, including plant and human pathogens and saprobes, suggesting the possibility that NPS6 activity provides oxidative stress protection during both saprobic and parasitic growth.

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30

Goettig, Peter. "Reversed Proteolysis—Proteases as Peptide Ligases". Catalysts 11, n. 1 (30 dicembre 2020): 33. http://dx.doi.org/10.3390/catal11010033.

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Historically, ligase activity by proteases was theoretically derived due to their catalyst nature, and it was experimentally observed as early as around 1900. Initially, the digestive proteases, such as pepsin, chymotrypsin, and trypsin were employed to perform in vitro syntheses of small peptides. Protease-catalyzed ligation is more efficient than peptide bond hydrolysis in organic solvents, representing control of the thermodynamic equilibrium. Peptide esters readily form acyl intermediates with serine and cysteine proteases, followed by peptide bond synthesis at the N-terminus of another residue. This type of reaction is under kinetic control, favoring aminolysis over hydrolysis. Although only a few natural peptide ligases are known, such as ubiquitin ligases, sortases, and legumains, the principle of proteases as general catalysts could be adapted to engineer some proteases accordingly. In particular, the serine proteases subtilisin and trypsin were converted to efficient ligases, which are known as subtiligase and trypsiligase. Together with sortases and legumains, they turned out to be very useful in linking peptides and proteins with a great variety of molecules, including biomarkers, sugars or building blocks with non-natural amino acids. Thus, these engineered enzymes are a promising branch for academic research and for pharmaceutical progress.

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31

Tsibulnikov, Sergey Y., Leonid N. Maslov, Alexander S. Gorbunov, Nikita S. Voronkov, Alla A. Boshchenko, Sergey V. Popov, Ekaterina S. Prokudina, Nirmal Singh e James M. Downey. "A Review of Humoral Factors in Remote Preconditioning of the Heart". Journal of Cardiovascular Pharmacology and Therapeutics 24, n. 5 (29 aprile 2019): 403–21. http://dx.doi.org/10.1177/1074248419841632.

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Abstract (sommario):

A humoral mechanism of cardioprotection by remote ischemic preconditioning (RIP) has been clearly demonstrated in various models of ischemia–reperfusion including upper and lower extremities, liver, and the mesenteric and renal arteries. A wide range of humoral factors for RIP have been proposed including hydrophobic peptides, opioid peptides, adenosine, prostanoids, endovanilloids, endocannabinoids, calcitonin gene-related peptide, leukotrienes, noradrenaline, adrenomedullin, erythropoietin, apolipoprotein, A-I glucagon-like peptide-1, interleukin 10, stromal cell-derived factor 1, and microRNAs. Virtually, all of the components of ischemic preconditioning’s signaling pathway such as nitric oxide synthase, protein kinase C, redox signaling, PI3-kinase/Akt, glycogen synthase kinase β, ERK1/2, mitoKATPchannels, Connexin 43, and STAT were all found to play a role. The signaling pattern also depends on which remote vascular bed was subjected to ischemia and on the time between applying the rip and myocardial ischemia occurs. Because there is convincing evidence for many seemingly diverse humoral components in RIP, the most likely explanation is that the overall mechanism is complex like that seen in ischemic preconditioning where multiple components are both in series and in parallel and interact with each other. Inhibition of any single component in the right circumstance may block the resulting protective effect, and selectively activating that component may trigger the protection. Identifying the humoral factors responsible for RIP might be useful in developing drugs that confer RIP’s protection in a more comfortable and reliable manner.

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32

Suring, Wouter, Dylan Hoogduin, Giang Le Ngoc, Abraham Brouwer, Nico M. van Straalen e Dick Roelofs. "Nonribosomal Peptide Synthetases in Animals". Genes 14, n. 9 (30 agosto 2023): 1741. http://dx.doi.org/10.3390/genes14091741.

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Nonribosomal peptide synthetases (NRPSs) are a class of cytosolic enzymes that synthesize a range of bio-active secondary metabolites including antibiotics and siderophores. They are widespread among both prokaryotes and eukaryotes but are considered rare among animals. Recently, several novel NRPS genes have been described in nematodes, schistosomes, and arthropods, which led us to investigate how prevalent NRPS genes are in the animal kingdom. We screened 1059 sequenced animal genomes and showed that NRPSs were present in 7 out of the 19 phyla analyzed. A phylogenetic analysis showed that the identified NRPSs form clades distinct from other adenylate-forming enzymes that contain similar domains such as fatty acid synthases. NRPSs show a remarkably scattered distribution over the animal kingdom. They are especially abundant in rotifers and nematodes. In rotifers, we found a large variety of domain architectures and predicted substrates. In the nematode Plectus sambesii, we identified the beta-lactam biosynthesis genes L-δ-(α-aminoadipoyl)-L-cysteinyl-D-valine synthetase, isopenicillin N synthase, and deacetoxycephalosporin C synthase that catalyze the formation of beta-lactam antibiotics in fungi and bacteria. These genes are also present in several species of Collembola, but not in other hexapods analyzed so far. In conclusion, our survey showed that NRPS genes are more abundant and widespread in animals than previously known.

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33

Hebecker, Stefanie, Joern Krausze, Tatjana Hasenkampf, Julia Schneider, Maike Groenewold, Joachim Reichelt, Dieter Jahn, Dirk W. Heinz e Jürgen Moser. "Structures of two bacterial resistance factors mediating tRNA-dependent aminoacylation of phosphatidylglycerol with lysine or alanine". Proceedings of the National Academy of Sciences 112, n. 34 (10 agosto 2015): 10691–96. http://dx.doi.org/10.1073/pnas.1511167112.

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The cytoplasmic membrane is probably the most important physical barrier between microbes and the surrounding habitat. Aminoacylation of the polar head group of the phospholipid phosphatidylglycerol (PG) catalyzed by Ala-tRNAAla–dependent alanyl-phosphatidylglycerol synthase (A-PGS) or by Lys-tRNALys–dependent lysyl-phosphatidylglycerol synthase (L-PGS) enables bacteria to cope with cationic peptides that are harmful to the integrity of the cell membrane. Accordingly, these synthases also have been designated as multiple peptide resistance factors (MprF). They consist of a separable C-terminal catalytic domain and an N-terminal transmembrane flippase domain. Here we present the X-ray crystallographic structure of the catalytic domain of A-PGS from the opportunistic human pathogen Pseudomonas aeruginosa. In parallel, the structure of the related lysyl-phosphatidylglycerol–specific L-PGS domain from Bacillus licheniformis in complex with the substrate analog L-lysine amide is presented. Both proteins reveal a continuous tunnel that allows the hydrophobic lipid substrate PG and the polar aminoacyl-tRNA substrate to access the catalytic site from opposite directions. Substrate recognition of A-PGS versus L-PGS was investigated using misacylated tRNA variants. The structural work presented here in combination with biochemical experiments using artificial tRNA or artificial lipid substrates reveals the tRNA acceptor stem, the aminoacyl moiety, and the polar head group of PG as the main determinants for substrate recognition. A mutagenesis approach yielded the complementary amino acid determinants of tRNA interaction. These results have broad implications for the design of L-PGS and A-PGS inhibitors that could render microbial pathogens more susceptible to antimicrobial compounds.

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34

Brinkworth, Craig S., Tara L. Pukala, John H. Bowie e Michael J. Tyler. "Host Defence Peptides from the Skin Glands of Australian Amphibians. Caerulein Neuropeptides and Antimicrobial, Anticancer, and nNOS Inhibiting Citropins from the Glandular Frog Litoria subglandulosa". Australian Journal of Chemistry 57, n. 7 (2004): 693. http://dx.doi.org/10.1071/ch03325.

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Abstract (sommario):

The host defence peptides from the skin secretions of the Australian Glandular Frog (Litoria subglandulosa) are similar to those of the closely related species Litoria citropa. Both species produce several potent caerulein neuropeptides and antimicrobial- and anticancer-active citropin peptides. The major neuropeptides from Litoria subglandulosa are caerulein 1.1 [pGlu Gln Asp Tyr(SO3) Thr Gly Trp Met Asp Phe–NH2], caerulein 1.2 [pGlu Gln Asp Tyr(SO3) Thr Gly Trp Phe Asp Phe–NH2], and caerulein 2.1 [pGlu Gln Asp Tyr(SO3) Thr Gly Ala His Met Phe–NH2], all of which are smooth muscle active. The major peptide, citropin 1.2 [Gly Leu Phe Asp Ile Ile Lys Lys Val Ala Ser Val Val Gly Gly Leu–NH2], is a wide-spectrum antibiotic and anticancer agent at the micromolar concentration. Citropin 1.2 also inhibits the formation of nitric oxide by the enzyme neuronal nitric oxide synthase (nNOS) at the micromolar concentration. Another peptide, citropin 2.2 [Gly Leu Ile Ser Ile Gly Lys Ala Leu Gly Gly Leu Ile Val Asp Val Leu Lys Pro Lys Ser–OH], also inhibits nNOS.

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35

Basilicata, Manuela Giovanna, Giacomo Pepe, Shara Francesca Rapa, Fabrizio Merciai, Carmine Ostacolo, Michele Manfra, Veronica Di Sarno et al. "Anti-Inflammatory and Antioxidant Properties of Dehydrated Potato-Derived Bioactive Compounds in Intestinal Cells". International Journal of Molecular Sciences 20, n. 23 (3 dicembre 2019): 6087. http://dx.doi.org/10.3390/ijms20236087.

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Abstract (sommario):

Inflammation and oxidative stress are always more recognized as responsible for chronic disease at the intestinal level. Currently, a growing interest is addressed to the discovery of diet-derived products which have anti-inflammatory and antioxidant properties. This work aims to characterize the pharmacological potential of dehydrated potatoes. For this purpose, a simulated gastrointestinal digestion was carried out. The bioaccessible peptides were fractionated on the basis of their molecular weight and tested on intestinal epithelial cells (IEC-6) under oxidative and inflammatory conditions. Our results demonstrate that the tested peptide fractions were able to significantly inhibit tumor necrosis factor-α release and cycloxygenase-2 and inducible nitric oxide synthase expression. The tested peptides also showed significant antioxidant activity, being able to both reduce reactive oxygen species (ROS) release, also from mitochondria, and nitrotyrosine formation, and increase the antioxidant response by heme oxygenase-1 and superoxide dismutase expression. Moreover, the peptide fractions were able to significantly increase the wound repair in IEC-6. The obtained results indicate the anti-inflammatory and antioxidant potential of dehydrated potatoes at the intestinal level.

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36

Hayashi, Yukimasa, Chiaki W. Nakagawa, Duangchan Uyakul, Kunio Imai, Minoru Isobe e Toshio Goto. "The change of cadystin components in Cd-binding peptides from the fission yeast during their induction by cadmium". Biochemistry and Cell Biology 66, n. 4 (1 aprile 1988): 288–95. http://dx.doi.org/10.1139/o88-038.

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Abstract (sommario):

Previously we reported that, upon exposure to Cd, Cd-bindimg peptides (Cd-BP1 and Cd-BP2) were induced in the fission yeast and that these Cd-BPs were composed of Cd atoms and multiples of the unit peptide cadystin. In this paper, the changes of relative amounts of cadystin species in each Cd-BP were determined during their induction by Cd in the logarithmically growing yeast. The preferential syntheses of the smaller cadystin species, in the early stages of induction by Cd and of the larger cadystin species at the late stage of induction suggested the biosynthetic pathway of cadystins in the fission yeast. Binding affinities of Cd to glutathione and cadystins indicate that the larger peptides bind Cd more firmly than du the smaller peptides, coinciding with the preferential synthesis of the larger peptides with the higher concentration of Cd in the cell at the late stage of Cd induction.

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37

Khavinson, Vladimir Khatskelevich, Irina Grigor’evna Popovich, Natalia Sergeevna Linkova, Ekaterina Sergeevna Mironova e Anastasiia Romanovna Ilina. "Peptide Regulation of Gene Expression: A Systematic Review". Molecules 26, n. 22 (22 novembre 2021): 7053. http://dx.doi.org/10.3390/molecules26227053.

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Abstract (sommario):

Peptides are characterized by their wide range of biological activity: they regulate functions of the endocrine, nervous, and immune systems. The mechanism of such action of peptides involves their ability to regulate gene expression and protein synthesis in plants, microorganisms, insects, birds, rodents, primates, and humans. Short peptides, consisting of 2–7 amino acid residues, can penetrate into the nuclei and nucleoli of cells and interact with the nucleosome, the histone proteins, and both single- and double-stranded DNA. DNA–peptide interactions, including sequence recognition in gene promoters, are important for template-directed synthetic reactions, replication, transcription, and reparation. Peptides can regulate the status of DNA methylation, which is an epigenetic mechanism for the activation or repression of genes in both the normal condition, as well as in cases of pathology and senescence. In this context, one can assume that short peptides were evolutionarily among the first signaling molecules that regulated the reactions of template-directed syntheses. This situation enhances the prospects of developing effective and safe immunoregulatory, neuroprotective, antimicrobial, antiviral, and other drugs based on short peptides.

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38

Guo, Yu, Jia Zhang, Ji-Cheng Wang, Feng-Xiang Yan, Bing-Yang Zhu, Hong-Lin Huang e Duan-Fang Liao. "Identification of Peptides Inhibiting Adhesion of Monocytes to the Injured Vascular Endothelial Cells through Phage-displaying Screening". Acta Biochimica et Biophysica Sinica 37, n. 4 (1 aprile 2005): 227–33. http://dx.doi.org/10.1111/j.1745-7270.2005.00039.x.

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AbstractUsing oxidized low-density lipoprotein (LDL)-injured vascular endothelial cells (ECs) as target cells, peptides specifically binding to the injured ECs were screened from a phage-displaying peptide library by using the whole-cell screening technique after three cycles of the “adsorption-elution-amplification” procedure. Positive phage clones were identified by ELISA, and the inserted amino acid sequences in the displaying peptides were deduced from confirmation with DNA sequencing. The adhesion rate of ECs to monocytes was evaluated by cell counting. The activity of endothelial nitric oxide synthase (eNOS), and the expression levels of caveolin-1 and intercellular adhesion molecule-1 (ICAM-1) were determined by Western blotting. Six positive clones specifically binding to injured ECV304 endothelial cells were selected from fourteen clones. Interestingly, four phages had peptides with tandem leucine, and two of these even shared an identical sequence. Functional analysis demonstrated that the YCPRYVRRKLENELLVL peptide shared by two clones inhibited the expression of ICAM-1, increased nitric oxide concentration in the culture media, and upregulated the expression of caveolin-1 and eNOS. As a result, the adhesion rate of monocytes to ECV304 cells was significantly reduced by 12.1%. These data suggest that the anti-adhesion effect of these novel peptides is related to the regulation of the caveolin-1/nitric oxide signal transduction pathway, and could be of use in potential therapeutic agents against certain cardiovascular diseases initiated by vascular endothelial cell damage.

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Eckert, Heiner, Barbara Forster e Christoph Seidel. "Vollständige Maskierung der –Gly-Bindungen mit dem stark lipophilen und chromophoren Ferrocenylmethyl[Fem]-Rest bei Peptidsynthesen von Hexaglycin und Leu-Enkephalin / Total Masking –Gly Bonds by Highly Lipophilic and Chromophoric Ferrocenylmethyl [Fem] Residue in Peptide Syntheses of Hexaglycine and Leu-Enkephalin". Zeitschrift für Naturforschung B 46, n. 3 (1 marzo 1991): 339–52. http://dx.doi.org/10.1515/znb-1991-0314.

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Abstract (sommario):

Highly lipophilic and chromophoric ferrocenylmethyl [Fem] residue is applied to syntheses of peptides hexaglycine and Leu-enkephalin, masking therein all –Gly bonds. Thereby Fem groups influence properties of Fem-peptide derivatives advantageously both in chemosyntheses and cleaning operations, leading to constantly high yields et each step. Despite of its volumous dimension the Fem residue can be introduced into each peptide bond of oligoglycine by succeeding one another of building blocks of H–Fem–Gly–OMe. Strong alkaline conditions during the hydrolyses of methyl esters occurring several times in peptide derivatives do not influence the Gly–Gly-bond at all. Total protected derivatives BOC–(Fem–Gly–)6OMe and BOC–Tyr(tBu)–(Fem–Gly–)2Phe–Leu–OtBu even are soluble in hexane/ethylacetate (1:1).

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40

Ribeiro, Ana R. M., Helena P. Felgueiras, Susana P. G. Costa e Sílvia M. M. A. Pereira-Lima. "Synthesis of Peptaibolin, an Antimicrobial Peptide". Proceedings 78, n. 1 (1 dicembre 2020): 47. http://dx.doi.org/10.3390/iecp2020-08654.

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Abstract (sommario):

To tackle one of the biggest global health problems, the resistance of microorganisms to antibiotics, a collective effort in the search for more effective agents against bacteria was required. Peptides with antimicrobial activity have been raising much attention as a promising alternative for antibiotics. Peptaibols, for instance, are a family of antimicrobial peptides (AMPs) with great biomedical potential, in which the Peptaibolin can be highlighted. This peptide has gained relevance due to its small amino acids content, only four, and its acetyl group and a phenylalaninol residue (Phol) at the N-terminal and C-terminal, respectively. Here, we report the synthesis of Peptaibolin through Solid Phase Peptide Synthesis assisted by Microwave heating (MW-SPPS) in a pre-loaded Phe-Wang resin. Starting from a loading of 0.51 mmol/g, two syntheses were made, using two different combinations of coupling reagents. The best option was DIC/Oxima, achieving a yield of 50.0%. Proton Nuclear Magnetic Resonance (1H-NMR) studies confirmed the peptide structure, while High Performance Liquid Chromatography (HPLC) verified the peptide purity. The peptide solubility was examined against several combinations of solvents. Peptaibolin was not soluble in water, only in organic solvents or in the combination of both. Antimicrobial testing was conducted using Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli, and Pseudomonas aeruginosa. Minimum inhibitory concentration studies demonstrated the resistance of bacteria to the peptide action and the peptide instability in bacterial growth conditions.

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41

Komaki, Hisayuki, e Tomohiko Tamura. "Polyketide Synthase and Nonribosomal Peptide Synthetase Gene Clusters in Type Strains of the Genus Phytohabitans". Life 10, n. 11 (27 ottobre 2020): 257. http://dx.doi.org/10.3390/life10110257.

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Abstract (sommario):

(1) Background: Phytohabitans is a recently established genus belonging to rare actinomycetes. It has been unclear if its members have the capacity to synthesize diverse secondary metabolites. Polyketide and nonribosomal peptide compounds are major secondary metabolites in actinomycetes and expected as a potential source for novel pharmaceuticals. (2) Methods: Whole genomes of Phytohabitans flavus NBRC 107702T, Phytohabitans rumicis NBRC 108638T, Phytohabitans houttuyneae NBRC 108639T, and Phytohabitans suffuscus NBRC 105367T were sequenced by PacBio. Polyketide synthase (PKS) and nonribosomal peptide synthetase (NRPS) gene clusters were bioinformatically analyzed in the genome sequences. (3) Results: These four strains harbored 10, 14, 18 and 14 PKS and NRPS gene clusters, respectively. Most of the gene clusters were annotated to synthesis unknown chemistries. (4) Conclusions: Members of the genus Phytohabitans are a possible source for novel and diverse polyketides and nonribosomal peptides.

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42

Carabaza, A., J. Arino, J. W. Fox, C. Villar-Palasi e J. J. Guinovart. "Purification, characterization and partial amino acid sequence of glycogen synthase from Saccharomyces cerevisiae". Biochemical Journal 268, n. 2 (1 giugno 1990): 401–7. http://dx.doi.org/10.1042/bj2680401.

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Abstract (sommario):

Glycogen synthase from Saccharomyces cerevisiae was purified to homogeneity. The enzyme showed a subunit molecular mass of 80 kDa. The holoenzyme appears to be a tetramer. Antibodies developed against purified yeast glycogen synthase inactivated the enzyme in yeast extracts and allowed the detection of the protein in Western blots. Amino acid analysis showed that the enzyme is very rich in glutamate and/or glutamine residues. The N-terminal sequence (11 amino acid residues) was determined. In addition, selected tryptic-digest peptides were purified by reverse-phase h.p.l.c. and submitted to gas-phase sequencing. Up to eight sequences (79 amino acid residues) could be aligned with the human muscle enzyme sequence. Levels of identity range between 37 and 100%, indicating that, although human and yeast glycogen synthases probably share some conserved regions, significant differences in their primary structure should be expected.

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43

Hati, Dian Laksamana, Sri Andarini, Dian Handayani, Djalal Rosyidi e Lilik Eka Radiati. "Characterization and Production of Goat Milk Kefir-Peptide on Triglyceride Synthesis of Cell Model of 3T3-L1". Jurnal Ilmu dan Teknologi Hasil Ternak 18, n. 1 (1 marzo 2023): 1–11. http://dx.doi.org/10.21776/ub.jitek.2023.018.01.1.

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Abstract (sommario):

Goat milk kefir (GMK) refers to fermented products, generated through fermenting milk with microbial culture called kefir grains. Prior studies have reported the changes in kefir quality properties during aging process in which fermentation continues, resulting in changes of the peptide content. This research aims to investigate the effect of aging time on GMK–peptide characteristics to inhibite triglyceride syntheses on cells model of 3T3-L1. In this study, GMK were stored at 4 ± 1 oC for 0, 2, 4, 6 and 8 weeks, respectively. The protein profile was characterizedby implementing SDS-PAGE. The result of experiment indicated no protein degradation during the 6 weeks of aging period particularly for high molecular weight at 84 kDa, 80 kDa and 65 kDa. The GMK-supernatant from 8 weeks storage was performed by applying ultrafiltration membrane cut off < 30 kDa (UFC8 030.08). GMK-filtrate fractions (GMK-peptide) was collected as peptides. After 8 weeks of aging period, kefir protein profile was found to consist of peptide fractions and amino acid. The proteolytic activity of kefir grain increased linearly along with aging time (0-8 weeks). During aging period, the proteolytic activity of grain kefir released peptides and amino acid. In particular, the antioxidant activities were found significantly different (p<0.05) during aging periods. The antioxidant activities of GMK-peptide increased along with the elevating peptide concentration, from 3.30 % to 55.73%, with derivate by GMK-peptides of 2.75 – 10.39 mg/ml. Obesity associated with adipocyte hypertrophy occurred when TG accumulation.GMK-peptide of 100 mg/ml indicated the lowest TG level (2.00 ± 0.03 mg/dl). This finding was in line with the inhibition of TG synthesis (61.14 ± 3.26 %). However, GMK-peptide contained antioxidant potency due to may be corelated with decreasing TG synthesis.The study thus suggested the important role of kefir to prolong aging in generating higher peptide bioactive as antioxidant and inhibition of TG synthesis of cell model of 3T3-L1

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44

Huo, Li-Jie, Peng-Yuan Lu, Dian-Xiang Li e Xiu-Zhen Shi. "The sORF-Encoded Peptides, ATP Synthase Subunits, Facilitate WSSV Duplication in Shrimp". Viruses 14, n. 11 (4 novembre 2022): 2449. http://dx.doi.org/10.3390/v14112449.

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Short open reading frames (sORFs) are a newly identified family of genes, and the functions of most sORF genes and their encoded peptides (SEPs) are still unknown. In this study, two ATP synthase subunits were identified in kuruma shrimp (Marsupenaeus japonicus) as SEPs, namely MjATP5I and MjATP5L. They were widely distributed in all of the tested tissues of shrimp and upregulated in hemocytes and intestines in response to WSSV challenge. The injection of recombinant proteins (rMjATP5I and rMjATP5L) increased the expression of Ie1 and Vp28, while the knockdown of MjATP5I and MjATP5L decreased the expression of Ie1 and Vp28. All of the results suggest that MjATP5I and MjATP5L were beneficial for WSSV replication. Further exploration found that MjATP5I and MjATP5L RNAi significantly improved the shrimp survival rates, reduced ATP production, and upregulated the expression of antimicrobial peptide genes post viral challenge, and the two ATPase subunits and Relish negatively regulated each other. These results reveal that MjATP5I and MjATP5L facilitated WSSV duplication by regulating the production of ATP contents and the expression of antimicrobial peptide genes in shrimp.

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45

Neilan, Brett A., Elke Dittmann, Leo Rouhiainen, R. Amanda Bass, Verena Schaub, Kaarina Sivonen e Thomas Börner. "Nonribosomal Peptide Synthesis and Toxigenicity of Cyanobacteria". Journal of Bacteriology 181, n. 13 (1 luglio 1999): 4089–97. http://dx.doi.org/10.1128/jb.181.13.4089-4097.1999.

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ABSTRACT Nonribosomal peptide synthesis is achieved in prokaryotes and lower eukaryotes by the thiotemplate function of large, modular enzyme complexes known collectively as peptide synthetases. These and other multifunctional enzyme complexes, such as polyketide synthases, are of interest due to their use in unnatural-product or combinatorial biosynthesis (R. McDaniel, S. Ebert-Khosla, D. A. Hopwood, and C. Khosla, Science 262:1546–1557, 1993; T. Stachelhaus, A. Schneider, and M. A. Marahiel, Science 269:69–72, 1995). Most nonribosomal peptides from microorganisms are classified as secondary metabolites; that is, they rarely have a role in primary metabolism, growth, or reproduction but have evolved to somehow benefit the producing organisms. Cyanobacteria produce a myriad array of secondary metabolites, including alkaloids, polyketides, and nonribosomal peptides, some of which are potent toxins. This paper addresses the molecular genetic basis of nonribosomal peptide synthesis in diverse species of cyanobacteria. Amplification of peptide synthetase genes was achieved by use of degenerate primers directed to conserved functional motifs of these modular enzyme complexes. Specific detection of the gene cluster encoding the biosynthetic pathway of the cyanobacterial toxin microcystin was shown for both cultured and uncultured samples. Blot hybridizations, DNA amplifications, sequencing, and evolutionary analysis revealed a broad distribution of peptide synthetase gene orthologues in cyanobacteria. The results demonstrate a molecular approach to assessing preexpression microbial functional diversity in uncultured cyanobacteria. The nonribosomal peptide biosynthetic pathways detected may lead to the discovery and engineering of novel antibiotics, immunosuppressants, or antiviral agents.

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Cui, Jing, Yongwei Feng, Ting Yang, Xinglong Wang e Heng Tang. "Computer-Aided Designing Peptide Inhibitors of Human Hematopoietic Prostaglandin D2 Synthase Combined Molecular Docking and Molecular Dynamics Simulation". Molecules 28, n. 15 (7 agosto 2023): 5933. http://dx.doi.org/10.3390/molecules28155933.

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Human hematopoietic prostaglandin D2 synthase (HPGDS) is involved in the production of prostaglandin D2, which participates in various physiological processes, including inflammation, allergic reactions, and sleep regulation. Inhibitors of HPGDS have been investigated as potential anti-inflammatory agents. For the investigation of potent HPGDS inhibitors, we carried out a computational modeling study combining molecular docking and molecular dynamics simulation for selecting and virtual confirming the designed binders. We selected the structure of HPGDS (PDB ID: 2CVD) carrying its native inhibitor compound HQL as our research target. The random 5-mer peptide library was created by building the 3-D structure of random peptides using Rosetta Buildpeptide and performing conformational optimization. Molecular docking was carried out by accommodating the peptides into the location of their native binder and then conducting docking using FlexPepDock. The two peptides RMYYY and VMYMI, which display the lowest binding energy against HPGDS, were selected to perform a comparative study. The interaction of RMYYY and VMYMI against HPGDS was further confirmed using molecular dynamics simulation and aligned with its native binder, HQL. We show the selected binders to have stronger binding energy and more frequent interactions against HPGDS than HQL. In addition, we analyzed the solubility, hydrophobicity, charge, and bioactivity of the generated peptides, and we show that the selected strong binder may be further used as therapeutic drugs.

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Chaiden, Chadaporn, Janthima Jaresitthikunchai, Narumon Phaonakrop, Sittiruk Roytrakul, Anusak Kerdsin e Suphachai Nuanualsuwan. "Unlocking the Secrets of Streptococcus suis: A peptidomics comparison of virulent and non-virulent serotypes 2, 14, 18, and 19". PLOS ONE 18, n. 6 (29 giugno 2023): e0287639. http://dx.doi.org/10.1371/journal.pone.0287639.

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Streptococcus suis (S. suis) is an important bacterial pathogen, that causes serious infections in humans and pigs. Although numerous virulence factors have been proposed, their particular role in pathogenesis is still inconclusive. The current study explored putative peptides responsible for the virulence of S. suis serotype 2 (SS2). Thus, the peptidome of highly virulent SS2, less prevalent SS14, and rarely reported serotypes SS18 and SS19 were comparatively analyzed using a high-performance liquid chromatography-mass spectrometry method (LC-MS/MS). Six serotype-specific peptides, 2,3,4,5-tetrahydropyridine-2,6-dicarboxylate N-acetyltransferase (DapH), alanine racemase (Alr), CCA-adding enzyme (CCA), peptide chain release factor 3 (RF3), ATP synthase subunit delta (F0F1-ATPases) and aspartate carbamoyltransferase (ATCase), were expressed moderately to highly only in the SS2 peptidome with p-values of less than 0.05. Some of these proteins are responsible for bacterial cellular stability; especially, Alr was highly expressed in the SS2 peptidome and is associated with peptidoglycan biosynthesis and bacterial cell wall formation. This study indicated that these serotype-specific peptides, which were significantly expressed by virulent SS2, could serve as putative virulence factors to promote its competitiveness with other coexistences in a particular condition. Further in vivo studies of these peptides should be performed to confirm the virulence roles of these identified peptides.

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Bai, T. R., e A. M. Bramley. "Effect of an inhibitor of nitric oxide synthase on neural relaxation of human bronchi". American Journal of Physiology-Lung Cellular and Molecular Physiology 264, n. 5 (1 maggio 1993): L425—L430. http://dx.doi.org/10.1152/ajplung.1993.264.5.l425.

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This study examines the roles of peptides and nitric oxide (NO) as mediators of inhibitory nonadrenergic, noncholinergic (NANCi) neurons in human and guinea pig airways in vitro. Tissues were contracted with 0.3 microM methacholine (MCh) and relaxation studied before and after the addition of the peptidase alpha-chymotrypsin (alpha-CT) (2 U/ml) and NG-nitro-L-arginine methyl ester (L-NAME 0.1-1.1 mM), an inhibitor of NO synthase, the enzyme catalyzing the formation of NO. alpha-CT alone, in comparison to parallel time controls, inhibited control relaxation to electrical field stimulation (EFS) by 29.2 +/- 8.6% in guinea pig tracheae (n = 9), whereas a small augmentation of relaxation was observed in human bronchi (n = 7). L-NAME inhibited the NANCi response in both guinea pig tracheae and human bronchi: in guinea pig tracheae, maximal inhibition of the alpha-CT-insensitive relaxation was 59.3 +/- 11.5% (SE, P = 0.003) at low frequencies (4-16 Hz) and 28.6 +/- 8.9% (P = 0.08) at 32 Hz; in human bronchi, the maximal inhibition was 37.7 +/- 9.3% (P = 0.008) at 8 or 16 Hz, and 37.9 +/- 5.9% (P = 0.005) at 32 Hz. Inhibition was greater after repeated baseline EFS for 90 min before initiation of contraction with MCh and addition of L-NAME (59.8 +/- 13.9% after repeated baseline EFS, n = 4; vs. 34.9 +/- 6.2% without repeated baseline EFS, n = 9, P = 0.025). Relaxant responses to sodium nitroprusside, vasoactive intestinal peptide, and isoproterenol were not affected by L-NAME. L-Arginine (10 mM), a precursor of NO, partially reversed the effect of L-NAME.(ABSTRACT TRUNCATED AT 250 WORDS)

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Jankowski, M., D. Wang, S. Mukaddam-Daher e J. Gutkowska. "Pregnancy alters nitric oxide synthase and natriuretic peptide systems in the rat left ventricle". Journal of Endocrinology 184, n. 1 (gennaio 2005): 209–17. http://dx.doi.org/10.1677/joe.1.05702.

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Cyclic guanosine monophosphate (cGMP), which is implicated in cardiac cell growth and function, is synthesized by cytoplasmic soluble guanylyl cyclase (GC) stimulated via nitric oxide (NO) and by particulate membrane-bound GC activated via natriuretic peptides. We investigated possible cGMP elevation in the left ventricle (LV) of rats developing physiologic LV hypertrophy during gestation. Furthermore, expression of estrogen receptors (ER) and oxytocin receptors (OTR) was evaluated because their activation stimulates NO and atrial natriuretic peptide (ANP) release from the heart. Compared with nonpregnant controls, Sprague-Dawley rats on day 7 of gestation had similar heart weights, but, on days 14 and 21, ventricular mass increased by 12% and 28% respectively (P< 0.05). LV cGMP concentration was elevated at day 14 of gestation (3.25 ± 0.12 vs 4.65 ± 0.17 pmol/g wet weight, P< 0.01) but decreased at day 21 (2.45 ± 0.09 pmol/g, P< 0.05) to increase again on postpartum day 1 (6.01 ± 0.15 pmol/g) and day 4 (9.21 ± 1.79 pmol/g). Changes in endothelial nitric oxide synthase (eNOS), inducible NOS (iNOS), OTR and ERα, but not ERβ, proteins paralleled the pregnancy-related cGMP changes in the LV. In contrast, ANP mRNA of the LV remained at control level throughout gestation but increased postpartum, whereas brain natriuretic peptide (BNP) expression declined at term and increased postpartum. The particulate GC natriuretic peptide receptors (GC-A and GC-B) transcripts were already lower at day 14 of gestation. Natriuretic peptide clearance receptor (NPR-C) transcript was not altered on days 7 and 14, but increased at term. We conclude that cGMP concentration in the rat LV is influenced by both NOS and natriuretic peptide systems and may be involved in the changes of LV contractility and hypertrophy that occur during rat gestation.

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Konduri, Girija G., Adeleye J. Afolayan, Annie Eis, Kirkwood A. Pritchard e Ru-Jeng Teng. "Interaction of endothelial nitric oxide synthase with mitochondria regulates oxidative stress and function in fetal pulmonary artery endothelial cells". American Journal of Physiology-Lung Cellular and Molecular Physiology 309, n. 9 (1 novembre 2015): L1009—L1017. http://dx.doi.org/10.1152/ajplung.00386.2014.

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An increase in oxygen tension at birth is one of the key signals that initiate pulmonary vasodilation in the fetal lung. We investigated the hypothesis that targeting endothelial nitric oxide synthase (eNOS) to the mitochondrial outer membrane regulates reactive oxygen species (ROS) formation in the fetal pulmonary artery endothelial cells (PAEC) during this transition. We isolated PAEC and pulmonary arteries from 137-day gestation fetal lambs (term = 144 days). We exposed PAEC to a simulated transition from fetal to (3% O2) to normoxic (21%) or hyperoxic (95% O2) postnatal Po2 or to the nitric oxide synthase (NOS) agonist ATP. We assessed the effect of O2 and ATP on eNOS interactions with the mitochondrial outer membrane protein porin and with the chaperone hsp90. We also investigated the effect of decoy peptides that blocked eNOS interactions with porin or hsp90 on PAEC angiogenesis and vasodilator function of pulmonary arteries. Transition of fetal PAEC from 3 to 21% O2 but not to 95% O2 or exposure to ATP increased eNOS association with hsp90 and porin. Decoy peptides that blocked eNOS interactions decreased NO release, increased O2 consumption and mitochondrial ROS levels, and impaired PAEC angiogenesis. Decoy peptides also inhibited the relaxation responses of pulmonary artery rings and dilation of resistance size pulmonary arteries to ATP. The mitochondrial-antioxidant mito-ubiquinone restored the response to ATP in decoy peptide-treated pulmonary arteries. These data indicate that targeting eNOS to mitochondria decreases endothelial oxidative stress and facilitates vasodilation in fetal pulmonary circulation at birth.

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