Littérature scientifique sur le sujet « Antimicrobial peptid »
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Articles de revues sur le sujet "Antimicrobial peptid"
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Burgettiné Böszörményi, Erzsébet, István Barcs, Gyula Domján, Katalin Bélafiné Bakó, András Fodor, László Makrai et Dávid Vozik. « A Xenorhabdus budapestensis entomopatogén baktérium sejtmentes fermentlevének és tisztítottfehérje-frakciójának antimikrobiális hatása néhány zoonoticus baktériumra ». Orvosi Hetilap 156, no 44 (novembre 2015) : 1782–86. http://dx.doi.org/10.1556/650.2015.30274.
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Introduction: Many multi-resistant patogens appear continuously resulting in a permanent need for the development of novel antibiotics. A large number of antibiotics introduced in clinical and veterinary practices are not effective. Antibacterial peptides with unusual mode of action may represent a promising option against multi-resistant pathogens. The entomopathogenic Xenorhabdus budapestensis bacteria produce several different antimicrobial peptides compounds such as bicornutin-A and fabclavin. Aim: The aim of the authors was to evaluate the in vitro antibacterial effect of Xenorhabdus budapestensis using zoonotic patogen bacteria. Method: Cell-free conditioned media and purified peptide fractions of Xenorhabdus budapestensis were tested on Gram-positive (Rhodococcus equi, Erysipelothrix rhusiopathia, Staphylococcus aureus, Streptococcus equi, Corynebacterium pseudotuberculosis, Listeria monocytagenes) and Gram-negative bacteria (Salmonella gallinarum, Salmonella derbi, Bordatella bronchoseptica, Escherichia coli, Pasteurella multocida, Aeromonas hydrophila) using agar diffusion test on blood agar plates. Results: It was found that Xenorhabdus budapestensis bacteria produced compounds with strong and dose-dependent effects on the tested organisms. Purified peptid fraction exerted a more marked effect than cell free conditioned media. Gram-positive bacteria were more sensitive to this antibacterial effect than Gram-negative bacteria. Conclusions: Antibacterial peptide compound from Xenorhabdus budapestensis exert marked antibacterial effect on zoonotic patogen bacteria and they should be further evaluated in future for their potential use in the control or prevention of zoonoses. Orv. Hetil., 2015, 156(44), 1782–1786.
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Almsned, Fahad. « Designing Antimicrobial Peptide : Current Status ». Journal of Medical Science And clinical Research 05, no 03 (26 mars 2016) : 19282–94. http://dx.doi.org/10.18535/jmscr/v5i3.153.
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Browne, Katrina, Sudip Chakraborty, Renxun Chen, Mark DP Willcox, David StClair Black, William R. Walsh et Naresh Kumar. « A New Era of Antibiotics : The Clinical Potential of Antimicrobial Peptides ». International Journal of Molecular Sciences 21, no 19 (24 septembre 2020) : 7047. http://dx.doi.org/10.3390/ijms21197047.
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Antimicrobial resistance is a multifaceted crisis, imposing a serious threat to global health. The traditional antibiotic pipeline has been exhausted, prompting research into alternate antimicrobial strategies. Inspired by nature, antimicrobial peptides are rapidly gaining attention for their clinical potential as they present distinct advantages over traditional antibiotics. Antimicrobial peptides are found in all forms of life and demonstrate a pivotal role in the innate immune system. Many antimicrobial peptides are evolutionarily conserved, with limited propensity for resistance. Additionally, chemical modifications to the peptide backbone can be used to improve biological activity and stability and reduce toxicity. This review details the therapeutic potential of peptide-based antimicrobials, as well as the challenges needed to overcome in order for clinical translation. We explore the proposed mechanisms of activity, design of synthetic biomimics, and how this novel class of antimicrobial compound may address the need for effective antibiotics. Finally, we discuss commercially available peptide-based antimicrobials and antimicrobial peptides in clinical trials.
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Artuković Nadinić, Irena, Vladimir Mrljak, Marija Lipar, Marina Pavlak, Ljiljana Bedrica et Renata Barić Rafaj. « The peptide hormone hepcidin ». Veterinarska stanica 51, no 2 (27 mars 2020) : 187–98. http://dx.doi.org/10.46419/vs.51.2.9.
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Hepcidin je peptidni hormon i glavni je re- gulator metabolizma željeza. Otkriven je u humanom serumu i urinu 2000. godine i nazvan je LEAP-1 (engl. Liver Expressed Antimicrobial Protein). Nedugo nakon toga znanstvenici su pod vodstvom Tomasa Ganze u potrazi za antimikrobnim peptidima otkrili peptid povezan s upalom i nazvali ga “hepcidin”. Otkrili su da se sintetizira u jetri i da ima antimikrobna svojstva. Najveći broj istraživanja o djelovanju i regulaciji izlučivanja hepcidina učinjen je na mišjim modelima kada je ustanovljeno da se sinteza i izlučivanje hepcidina u miševa povećava u stanjima s povišenim količinama željeza u serumu i upalnim stanjima. Određivanje hepcidina u krvi i ostalim tjelesnim tekućinama određuje se imunološkim testovima s antihepcidinskim protutijelima - ELISA (prema engl. enzyme-linked immunosorbent assay) i masenom spektrometrijom. Koncentracije hepcidina u serumu određene masenom spektometrijom i koncentracije određene ELISA metodom dobro koreliraju. Imunološki testovi najtočnije mjere niske vrijednosti hepcidina, a masena spektrometrija točnije mjeri aktivnu formu hepcidina. Poremećaji u ekspresiji hepcidina javljaju se kod mnogih bolesti kao što su: anemija prouzročena kroničnim sistemskim bolestima, sideropenične anemije, maligne bolesti, hereditarne hemokromatoze i stanja s neefektivnom eritropoezom. Stoga mjerenje koncentracije hepcidina ima veliko značenje u dijagnostici i liječenju stanja u kojima je narušena ravnoteža željeza u organizmu. Napredak u razumijevanju uloge hepcidina u kontroli homeostaze željeza dovodi do novih mogućnosti liječenja u stanjima sa sniženim ili povišenim razinama željeza u organizmu. Hepcidin je nedavno identificiran kao akutno fazni protein s antimikrobnom i regulatornom funkcijom željeza. Mnogi su istra- živači pokazali interes za razvoj dijagnostičkog testa za mjerenje hepcidina u pasa. Ciljevi njihovog istraživanja bili su kloniranje i sekvenciranje gena psećeg hepcidina i prikupljanje preliminarnih podataka o pojavi hepcidina u pasa. Filogenetska analiza pokazala je da je humani hepcidin bio sličniji hepcidinu pasa nego hepcidinu glodavaca. U pasa, kao i u ljudi, hepcidin se najviše sinetitiza u jetri, a nešto slabije u bubrezima i plućnom tkivu pasa. Rezultat ovog istraživanja uspostavio je osnovu za buduća istraživanja psećeg hepcidina. Autori navode da psi mogu biti dobar model za istraživanje uloge hepcidina u ljudi.
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Chongsiriwatana, Nathaniel P., Tyler M. Miller, Modi Wetzler, Sergei Vakulenko, Amy J. Karlsson, Sean P. Palecek, Shahriar Mobashery et Annelise E. Barron. « Short Alkylated Peptoid Mimics of Antimicrobial Lipopeptides ». Antimicrobial Agents and Chemotherapy 55, no 1 (18 octobre 2010) : 417–20. http://dx.doi.org/10.1128/aac.01080-10.
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ABSTRACTWe report the creation of alkylated poly-N-substituted glycine (peptoid) mimics of antimicrobial lipopeptides with alkyl tails ranging from 5 to 13 carbons. In several cases, alkylation significantly improved the selectivity of the peptoids with no loss in antimicrobial potency. Using this technique, we synthesized an antimicrobial peptoid only 5 monomers in length with selective, broad-spectrum antimicrobial activity as potent as previously reported dodecameric peptoids and the antimicrobial peptide pexiganan.
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Haney, Evan F., Leonard T. Nguyen, David J. Schibli et Hans J. Vogel. « Design of a novel tryptophan-rich membrane-active antimicrobial peptide from the membrane-proximal region of the HIV glycoprotein, gp41 ». Beilstein Journal of Organic Chemistry 8 (24 juillet 2012) : 1172–84. http://dx.doi.org/10.3762/bjoc.8.130.
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A number of physicochemical characteristics have been described which contribute to the biological activity of antimicrobial peptides. This information was used to design a novel antimicrobial peptide sequence by using an intrinsically inactive membrane-associated peptide derived from the HIV glycoprotein, gp41, as a starting scaffold. This peptide corresponds to the tryptophan-rich membrane-proximal region of gp41, which is known to interact at the interfacial region of the viral membrane and adopts a helical structure in the presence of lipids. Three synthetic peptides were designed to increase the net positive charge and amphipathicity of this 19-residue peptide. Ultimately, the peptide with the greatest degree of amphipathicity and largest positive charge proved to be the most potent antimicrobial, and this peptide could be further modified to improve the antimicrobial activity. However, the other two peptides were relatively ineffective antimicrobials and instead proved to be extremely hemolytic. This work demonstrates a novel approach for the design of unexplored antimicrobial peptide sequences but it also reveals that the biological and cytotoxic activities of these polypeptides depend on a number of interrelated factors.
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Nava Lara, Rodrigo, Longendri Aguilera-Mendoza, Carlos Brizuela, Antonio Peña et Gabriel Del Rio. « Heterologous Machine Learning for the Identification of Antimicrobial Activity in Human-Targeted Drugs ». Molecules 24, no 7 (31 mars 2019) : 1258. http://dx.doi.org/10.3390/molecules24071258.
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The emergence of microbes resistant to common antibiotics represent a current treat to human health. It has been recently recognized that non-antibiotic labeled drugs may promote antibiotic-resistance mechanisms in the human microbiome by presenting a secondary antibiotic activity; hence, the development of computer-assisted procedures to identify antibiotic activity in human-targeted compounds may assist in preventing the emergence of resistant microbes. In this regard, it is worth noting that while most antibiotics used to treat human infectious diseases are non-peptidic compounds, most known antimicrobials nowadays are peptides, therefore all computer-based models aimed to predict antimicrobials either use small datasets of non-peptidic compounds rendering predictions with poor reliability or they predict antimicrobial peptides that are not currently used in humans. Here we report a machine-learning-based approach trained to identify gut antimicrobial compounds; a unique aspect of our model is the use of heterologous training sets, in which peptide and non-peptide antimicrobial compounds were used to increase the size of the training data set. Our results show that combining peptide and non-peptide antimicrobial compounds rendered the best classification of gut antimicrobial compounds. Furthermore, this classification model was tested on the latest human-approved drugs expecting to identify antibiotics with broad-spectrum activity and our results show that the model rendered predictions consistent with current knowledge about broad-spectrum antibiotics. Therefore, heterologous machine learning rendered an efficient computational approach to classify antimicrobial compounds.
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Zhang, Yong-lian, et Hsiao-Chang Chan. « S1h1-4 An epididymis-specific antimicrobial peptide has dual functions in sperm maturation(S1-h1 "Antimicrobial Peptides and Membrane Interactions",Symposia,Abstract,Meeting Program of EABS & ; BSJ 2006) ». Seibutsu Butsuri 46, supplement2 (2006) : S113. http://dx.doi.org/10.2142/biophys.46.s113_2.
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Sutyak Noll, Katia, Mark N. Prichard, Arkady Khaykin, Patrick J. Sinko et Michael L. Chikindas. « The Natural Antimicrobial Peptide Subtilosin Acts Synergistically with Glycerol Monolaurate, Lauric Arginate, and ε-Poly-l-Lysine against Bacterial Vaginosis-Associated Pathogens but Not Human Lactobacilli ». Antimicrobial Agents and Chemotherapy 56, no 4 (17 janvier 2012) : 1756–61. http://dx.doi.org/10.1128/aac.05861-11.
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ABSTRACTSubtilosin is a cyclical antimicrobial peptide produced byBacillus amyloliquefaciensthat has antimicrobial activity against the bacterial vaginosis-associated human pathogenGardnerella vaginalis. The ability of subtilosin to inhibitG. vaginalisalone and in combination with the natural antimicrobial agents glycerol monolaurate (Lauricidin), lauric arginate, and ε-poly-l-lysine was tested using a checkerboard approach. Subtilosin was found to act synergistically with all of the chosen antimicrobials. These promising results indicate that lower concentrations of subtilosin in combination with other compounds could effectively be used to inhibit growth of the pathogen, thereby decreasing the risk of developed antimicrobial resistance. This is the first report on the effects of subtilosin combined with other natural antimicrobials againstG. vaginalis.
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С., Саха, Ратрей П. et Мишра А. « ВЗАИМОДЕЙСТВИЕ АНТИМИКРОБНОГО ПЕПТИДА ЛАЗИОГЛОССИНА III С МОДЕЛЬНЫМИ ЛИПИДНЫМИ БИСЛОЯМИ ». Биофизика 67, no 2 (2022) : 250–63. http://dx.doi.org/10.31857/s0006302922020077.
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Лазиоглоссин-III - малый катионный пептид, обнаруженный в яде пчелы Lasioglossum laticeps. Сообщается, что он обладает сильной антимикробной активностью и слабым гемолитическим действием. В данной работе исследована природа взаимодействий лазиоглоссина-III с липидными бислоями в различной ориентации и его проникающая способность с помощью расчетов методом молекулярной динамики. Были проведены молекулярно-динамические расчеты лазиоглоссина-III на поверхности и внутри бислоев из чистых 1,2-димиристоил-sn-глицеро-3-фосфатидилхолина и 1-пальмитоил-2-олеил-sn-глицеро-3-фосфатидилхолина для определения взаимодействий «мембрана-пептид» и их эффектов. Обнаружено, что лазиоглоссин-III взаимодействовал с обоими типами бислоев с разными скоростями и демонстрировал дестабилизацию на границе раздела фаз «мембрана-вода» относительно стартового состояния пептида. Эти результаты позволяют говорить о наличии специфических взаимодействий между остатками лизина пептида и участками головок липидов, ответственных за общую стабильность пептида в липидных бислоях. Кроме того, результаты указывают на существенно больший угол наклона пептида и более высокую свободную энергию, а также на уменьшение толщины бислоя в случае бислоев 1,2-димиристоил-sn-глицеро-3-фосфатидилхолина в сравнении с 1-пальмитоил-2-олеил-sn-глицеро-3-фосфатидилхолином, вызываемые встраиванием пептида.
Thèses sur le sujet "Antimicrobial peptid"
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Dannehl, Claudia. « Fragments of the human antimicrobial LL-37 and their interaction with model membranes ». Phd thesis, Universität Potsdam, 2013. http://opus.kobv.de/ubp/volltexte/2013/6814/.
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A detailed description of the characteristics of antimicrobial peptides (AMPs) is highly demanded, since the resistance against traditional antibiotics is an emerging problem in medicine. They are part of the innate immune system in every organism, and they are very efficient in the protection against bacteria, viruses, fungi and even cancer cells. Their advantage is that their target is the cell membrane, in contrast to antibiotics which disturb the metabolism of the respective cell type. This allows AMPs to be more active and faster. The lack of an efficient therapy for some cancer types and the evolvement of resistance against existing antitumor agents make AMPs promising in cancer therapy besides being an alternative to traditional antibiotics.
The aim of this work was the physical-chemical characterization of two fragments of LL-37, a human antimicrobial peptide from the cathelicidin family. The fragments LL-32 and LL-20 exhibited contrary behavior in biological experiments concerning their activity against bacterial cells, human cells and human cancer cells. LL-32 had even a higher activity than LL-37, while LL-20 had almost no effect. The interaction of the two fragments with model membranes was systematically studied in this work to understand their mode of action. Planar lipid films were mainly applied as model systems in combination with IR-spectroscopy and X-ray scattering methods. Circular Dichroism spectroscopy in bulk systems completed the results.
In the first approach, the structure of the peptides was determined in aqueous solution and compared to the structure of the peptides at the air/water interface. In bulk, both peptides are in an unstructured conformation. Adsorbed and confined to at the air-water interface, the peptides differ drastically in their surface activity as well as in the secondary structure. While LL-32 transforms into an α-helix lying flat at the water surface, LL-20 stays partly unstructured. This is in good agreement with the high antimicrobial activity of LL-32.
In the second approach, experiments with lipid monolayers as biomimetic models for the cell membrane were performed. It could be shown that the peptides fluidize condensed monolayers of negatively charged DPPG which can be related to the thinning of a bacterial cell membrane. An interaction of the peptides with zwitterionic PCs, as models for mammalian cells, was not clearly observed, even though LL-32 is haemolytic.
In the third approach, the lipid monolayers were more adapted to the composition of human erythrocyte membranes by incorporating sphingomyelin (SM) into the PC monolayers. Physical-chemical properties of the lipid films were determined and the influence of the peptides on them was studied. It could be shown that the interaction of the more active LL-32 is strongly increased for heterogeneous lipid films containing both gel and fluid phases, while the interaction of LL-20 with the monolayers was unaffected. The results indicate an interaction of LL-32 with the membrane in a detergent-like way.
Additionally, the modelling of the peptide interaction with cancer cells was performed by incorporating some negatively charged lipids into the PC/SM monolayers, but the increased charge had no effect on the interaction of LL-32. It was concluded, that the high anti-cancer activity of the peptide originates from the changed fluidity of cell membrane rather than from the increased surface charge. Furthermore, similarities to the physical-chemical properties of melittin, an AMP from the bee venom, were demonstrated.Aufgrund der steigenden Resistenzen von Zellstämmen gegen traditionelle Therapeutika sind alternative medizinische Behandlungsmöglichkeiten für bakterielle Infektionen und Krebs stark gefragt. Antimikrobielle Peptide (AMPs) sind Bestandteil der unspezifischen Immunabwehr und kommen in jedem Organismus vor. AMPs lagern sich von außen an die Zellmembran an und zerstören ihre Integrität. Das macht sie effizient und vor allem schnell in der Wirkung gegen Bakterien, Viren, Pilzen und sogar Krebszellen. Das Ziel dieser Arbeit lag in der physikalisch-chemischen Charakterisierung zweier Peptidfragmente die unterschiedliche biologische Aktivität aufweisen. Die Peptide LL-32 und LL-20 waren Teile des humanen LL-37 aus der Kathelizidin-Familie. LL-32 wies eine stärke Aktivität als das Mutterpeptid auf, während LL-20 kaum aktiv gegen die verschiedenen Zelltypen war. In dieser Arbeit wurde die Wechselwirkung der Peptide mit Zellmembranen systematisch anhand von zweidimensionalen Modellmembranen in dieser Arbeit untersucht. Dafür wurden Filmwaagenmessungen mit IR-spektroskopischen und Röntgenstreumethoden gekoppelt. Circulardichroismus-Spektroskopie im Volumen komplementierte die Ergebnisse. In der ersten Näherung wurde die Struktur der Peptide in Lösung mit der Struktur an der Wasser/Luft-Grenzfläche verglichen. In wässriger Lösung sind beide Peptidfragmente unstrukturiert, nehmen jedoch eine α-helikale Sekundärstruktur an, wenn sie an die Wasser/Luft-Grenzfläche adsorbiert sind. Das biologisch unwirksamere LL-20 bleibt dabei teilweise ungeordnet. Das steht im Zusammenhang mit einer geringeren Grenzflächenaktivität des Peptids. In der Zweiten Näherung wurden Versuche mit Lipidmonoschichten als biomimetisches Modell für die Wechselwirkung mit der Zellmembran durchgeführt. Es konnte gezeigt werden, dass sich die Peptide fluidisierend auf negativ geladene Dipalmitylphosphatidylglycerol (DPPG) Monoschichten auswirken, was einer Membranverdünnung an Bakterienzellen entspricht. Eine Interaktion der Peptide mit zwitterionischem Phosphatidylcholin (PC), das als Modell für Säugetierzellen verwendet wurde, konnte nicht klar beobachtet werden, obwohl biologische Experimente das hämolytische Verhalten zumindest von LL-32 zeigten. In der dritten Näherung wurde das Membranmodell näher an die Membran von humanen Erythrozyten angepasst, indem gemischte Monoschichten aus Sphingomyelin (SM) und PC hergestellt wurden. Die physikalisch-chemischen Eigenschaften der Lipidfilme wurden zunächst ausgearbeitet und anschließend der Einfluss der Peptide untersucht. Es konnte anhand verschiedener Versuche gezeigt werden, dass die Wechselwirkung von LL-32 mit der Modellmembran verstärkt ist, wenn eine Koexistenz von fluiden und Gelphasen auftritt. Zusätzlich wurde die Wechselwirkung der Peptide mit der Membran von Krebszellen imitiert, indem ein geringer Anteil negativ geladener Lipide in die Monoschicht eingebaut wurde. Das hatte allerdings keinen nachweislichen Effekt, so dass geschlussfolgert werden konnte, dass die hohe Aktivität von LL-32 gegen Krebszellen ihren Grund in der veränderten Fluidität der Membran hat und nicht in der veränderten Oberflächenladung. Darüber hinaus wurden Ähnlichkeiten zu Melittin, einem AMP aus dem Bienengift, dargelegt. Die Ergebnisse dieser Arbeit sprechen für einen Detergenzien-artigen Wirkmechanismus des Peptids LL-32 an der Zellmembran.
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Das, Sanjit. « Methodological development in peptide chemistry for synthesis of antimicrobial and antifungal derivatives of marine natural peptides ». Thesis, Perpignan, 2018. http://www.theses.fr/2018PERP0054.
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La chimie de clic est devenue indispensable dans les nombreux domaines de chimie associée à la conception de médicament. Dans ce contexte, comme nous savons(connaissons) l'étude concernant l'impact d'insertion triazole sur la conformation de peptaibol est limitée, nous avons conduit l'étude pour examiner l'impact et l'adaptabilité de 1, 1 4-disubstituted, 2, l'insertion 3-triazole dans peptaibols différent. Selon le résultat de cette expérience touchant à l'activité réduite et la conformation perturbée de l'analogue peptaibol, le substitut dipeptide décoré du fragment triazole portant substituents hydrophobe divers a été inséré à très N-ter la partie du peptaibol. L'amélioration du bioactivity et de la restauration de la conformation pour les analogues peptaibol a été observée et le fait a été aussi soutenu par les résultats obtenus de l'étude biophysique des analogues choisis d'ALM F50/5. Nous avons plus loin prolongé notre étude pour employer notre stratégie à être appliqué sur le peptide P42 thérapeutique qui souffre de la limitation de manque de perméabilité et de stabilité. Le peptide P42 est impliqué dans le pathophysiology de la maladie d'Huntington neurodégénératif. Un total de 12 analogues de peptide de P42-camelote a été synthétisé par SPPS par notre protocole optimize. Dans la deuxième partie, nous avons développé une stratégie pour synthétiser lipopeptide cyclique produit de l'espèce cynaobacterial marine. Notre objectif principal était de synthétiser Hormothamnin A, undecapeptide cyclique consistant de plusieurs acides aminés artificiels incluant dehydroamino acide (Dhaa) qui fait la synthèse de ce peptide compliqué. En raison de cette raison, premièrement, nous avons voulu appliquer notre stratégie de synthétiser Trichormamide A, une sorte relativement plus simple de cylic lipopeptide. Après l'accomplissement de cette tâche, une première tentative a été faite pour synthétiser Hormothamnin A. Le résultat préliminaire de ceci est présenté dans cette section. Enfin, nous avons essayé de développer une méthodologie robuste pour synthétiser Fmoc-Dhaa dans la phase de solution et son insertion dans l'ordre peptaibol par une norme(un standard) SPPS le protocole. Les résultats préliminaires que nous avons concernant la synthèse Dhaa et son insertion dans peptaibol sont aussi discutés ici de plus avec la synthèse de phase solide de Bergofungin naturel DThe click chemistry has become indispensible in the many areas of chemistry associated with drug design. In this context, as we know the study concerning the impact of triazole insertion on the conformation of peptaibol is limited, we have conducted the study to investigate the impact and adaptability of the 1, 4-disubstituted 1, 2, 3-triazole insertion into different peptaibols. Depending on the outcome of this experiment relating to reduced activity and perturbed conformation of the peptaibol analogue, the dipeptide surrogate decorated with the triazole moiety bearing various hydrophobic substituents was inserted at the very N-ter part of the peptaibol. The improvement of the bioactivity and restoration of the conformation for the peptaibol analogues was observed and the fact was also supported by the results obtained from the biophysical study of the selected analogues of ALM F50/5. We have further extended our study to employ our strategy to be applied on the therapeutic P42 peptide which suffers from the limitation of lack of permeability and stability. P42 peptide is involved in the pathophysiology of neurodegenerative Huntington’s disease. A total of 12 analogues of P42-TAT peptide were synthesized through SPPS by our optimized protocol. In the second part, we have developed a strategy for synthesizing the cyclic lipopeptide originated from marine cynaobacterial species. Our main objective was to synthesize Hormothamnin A, a cyclic undecapeptide consisting of several unnatural amino acids including dehydroamino acid (Dhaa) which makes the synthesis of this peptide complicated. Due to this reason, firstly, we have chosen to apply our strategy to synthesize Trichormamide A, a relatively simpler kind of cylic lipopeptide. After accomplishing this task, a first attempt was made to synthesize Hormothamnin A. The preliminary result of this is presented in this section. At last, we have tried to develop a robust methodology to synthesize Fmoc-Dhaa in solution phase and its insertion into the peptaibol sequence through a standard SPPS protocol. The preliminary results we have got concerning the Dhaa synthesis and its insertion into peptaibol are also discussed here in addition with the solid phase synthesis of natural Bergofungin D
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Weichbrodt, Conrad. « Elektrophysiologische Charakterisierung des mitochondrialen Porins VDAC1 und des antimikrobiellen Peptids Dermcidin in lösungsmittelfreien Modellmembranen ». Doctoral thesis, Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2013. http://hdl.handle.net/11858/00-1735-0000-0001-BAA4-C.
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Shyam, Radhe. « Cationic amphipathic peptoid oligomers as antimicrobial peptide mimics ». Thesis, Université Clermont Auvergne (2017-2020), 2018. http://www.theses.fr/2018CLFAC048/document.
Texte intégralRésumé :
Les organismes vivants produisent des peptides antimicrobiens (PAMs) pour se protéger contre les microbes. La résistance croissante aux antibiotiques nécessite le développement de nouvelles stratégies thérapeutiques et les PAMs sont des candidats prometteurs pour résoudre ce problème. Ils possèdent une activité à large spectre et leur principal mécanisme d'action par perméation de la membrane engendre peu de phénomènes de résistance. Néanmoins, leur faible biodisponibilité empêche leur utilisation. Certaines limitations peuvent être surmontées en développant des mîmes de PAMs qui conservent leur activité mais avec un potentiel thérapeutique accru. Les peptoïdes (oligomères de N-alkylglycine) structurés en hélice cationique amphiphile sont de bons mimes de PAMs. Les peptoïdes sont plus flexibles que les peptides en raison de l'isomérie cis/trans des amides N,N-disubstitués ; cependant la conformation des amides peut être contrôlée par un choix judicieux des chaînes latérales. Le but de cette thèse est d'étudier l'influence de chaînes latérales(hydrophobes ou cationiques) bloquant la conformation des amides en cis et induisant une structure hélicoïdale de type PolyProline I (PPI) robuste, sur l’activité antibactérienne et la sélectivité de peptoïdes. La conception, la synthèse et l’étude conformationnelle de nouveaux oligomères peptoïdes cationiques portant des chaînes latérales de type tert-butyle et/ou triazolium ont été réalisées. Dans un premier temps, la synthèse en solution d'oligomères à base de tert-butyle a été développée puis une stratégie de synthèse en phase solide a été mise en place pour accéder aux oligomères à base de 1,2,3-triazolium. Ensuite, ces nouveaux oligomères ont été évalués pour leur activité vis à vis d’un panel de bactéries Gram-positive et Gram-négative, leur l'activité antibiofilm et leur sélectivité cellulaire. Enfin, pour visualiser les effets des peptoïdes amphiphiles sur les bactéries, une étude de microscopie a été réaliséeLiving organisms produce antimicrobial peptides (AMPs) to protect themselves against microbes.The growing problem of antimicrobial resistance calls for new therapeutic strategies and the natural AMPs have shown ground-breaking potential to address that issue. They show broad-spectrum activity and their main mechanism of action by bacterial cell membrane disruption implies low emergence of resistance which makes them potent candidates for replacing conventional antibiotics. Nevertheless, few hurdles are impeding their use, notably poor bioavailability profile. Some of these limitations can be overcome by developing peptidomimetics of AMPs which exhibit antibacterial activities together with enhanced therapeutic potential. Peptoids (i.e. N-alkyl glycine oligomers) adopting cationic amphipathic helical structures are mostly competent AMP mimetics. From a conformational point of view, peptoids are fundamentally more flexible than peptides primarily due to the cis/trans isomerism of N,N-disubstituted amides but studies in this area have shown that cis amide conformation can be controlled by careful choice of side-chain to set a PolyProline I-type helical structure of peptoids. In this thesis, the genesis of novel amphipathic cationic peptoids carrying cis-directing tert-butyl and/or triazolium-type side-chains and their untapped potential to act against bacteria will be discussed comprehensively. First, the solutionphase synthesis of tert-butyl-based oligomers was developed. Second, novel method of solid-phase submonomer synthesis was optimised to access 1,2,3-triazolium-based oligomers. Then, the synthesised cationic oligomers were evaluated for their antibacterial potential, followed by antibiofilm activity and cell selectivity assays. In the end, to have insights on the mode of action of amphipathic peptoids, microscopy was carried out
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Rolland, Jean-Luc. « Aspects moléculaires et biochimiques des stylicines, peptides multifonctionnels identifiés chez la crevette bleue du Pacifique Litopenaeus stylirostris (Crustacea, Decapoda) ». Thesis, Montpellier 2, 2010. http://www.theses.fr/2010MON20049.
Texte intégralRésumé :
Les travaux présentés dans ce mémoire ont été motivés par l'importance économique de l'élevage de la crevette bleue du pacifique Litopenaeus stylirostris dont les fortes mortalités sont principalement dues au développement de maladies bactériennes et virales. Ils ont consisté en la caractérisation des deux premiers membres d'une famille originale de peptides multifonctionnels présents chez les crevettes pénéides, les stylicines. Ces peptides, nommés stylicines 1 et 2, sont des peptides anioniques (pI < 6.0), formés d'une région amino-terminale riche en résidus de type proline et d'une région carboxy-terminale riche de treize résidus cystéines. Ces molécules sont synthétisées et stockées dans de petits granules présents dans le cytoplasme des hémocytes. Pour mieux appréhender leurs rôles dans la réponse immunitaire des crevettes à une infection par des Vibrio, leurs formes recombinantes ont été produites dans E. coli BL21 (DE3) plysS, purifiées et caractérisées. Les deux rstylicines présentent des activités antiproliférative et anticoagulante. Seule la rstylicine1 présente des activités antimicrobiennes : antifongique sur Fusarium oxysporum (CMI<2.5 µM), et antibactérienne (bactériostatique) sur Vibrio sp (CMI<80 µM). Ce peptide est également capable de se lier aux LPS des bactéries à Gram (-) (Kd= 9.6x10-8 M) et d'agglutiner V. penaeicida "in vitro". Enfin, l'existence de gènes codant des formes modifiées de la stylicine1, chez certaines crevettes, pourrait être en relation avec une diminution de la résistante des individus aux infectionsThe work reported here was motivated by the economical importance of the pacific blue shrimp Litopenaeus stylirostris farming where high mortality rates are due to bacterial and viral diseases. It consists in the characterisation of two original peptides, the first members of a new multifunctional family of peptides from peneide shrimps, the stylicines. Those two peptides, named stylicines 1 and 2, are negatively charged (pI < 6.0), and characterised by a proline-rich N-terminal region and a C-terminal region containing 13 cysteine residues. Stylicines are synthesized by heamocytes where they are stored within small cytoplasmic granules. To understand the role of these peptides in the immune response of shrimps to a vibrio infection, their recombinant forms were produced in E. coli BL21 (DE3) plysS, purified and characterised. The two rstylicines display biological anti-proliferative and blood clotting activities. Only rstylicine 1 displays antimicrobial activities: antifungal against Fusarium oxysporum (MIC<2.5µM) and bacteriostatic against Gram (−) bacteria, Vibrio sp. (MIC<80µM). Moreover this peptide displays an LPS-binding activity (dissociation constant (Kd) of 9.6×10−8 M) and agglutinate Vibrio. penaeicida "in vitro". Finally, the presence of sequences coding for modified forms of stylicine 1 in some shrimp's genome may be in relation with their lower ability to survive infections
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FASOLI, Anna. « Biophysical mechanisms of membrane perturbation and signal transduction produced by proteins and peptides ». Doctoral thesis, Università degli studi di Ferrara, 2015. http://hdl.handle.net/11392/2388995.
Texte intégralRésumé :
My primary research interest is focused on the field of cellular electrical activity, ranging from the ion channels that generates it, up to the study of intracellular processes regulating it, and new generation of drugs. For this purpose, during my Ph.D. I have learnt and improved different cutting-edge techniques, i.e. the patch-clamp technique, the fluorescence imaging, and the synthesis and use of model membranes. Moreover, to explore particular aspects of these molecular mechanisms and to overcome the issues raised during the investigations, non-conventional strategies were employed, even requiring the development of specific devices not commercially available.
In summary, my Ph.D. thesis is focused on two projects: the biophysical characterization of a particular class of membrane active peptides, and the modulation of visual phototransduction in vertebrate cones.
In the first project, I investigated the mechanism of membrane perturbation of cell-penetrating and antimicrobial peptides using the patch-clamp technique. Cell-penetrating peptides (CPPs) are short peptides that are able to cross the cell membrane via energy-dependent and/or independent mechanisms, with low toxicity and without the use of specific receptors. This ability is preserved even when CPPs are conjugated with a large cargo, thus representing an innovative pharmacological tool for the diffusion of large and hydrophilic drugs into the cells. Despite the mechanism of cellular uptake is still debated in literature, it has been proved that it can occur by either direct translocation or endocytosis. In the latter case, though, the cargo-peptide complex often remains trapped inside the endocytic vesicles and is not able to reach its therapeutic target. A possible solution to this problem could be found in another class of small peptides, similar to CPPs, i.e. the antimicrobial peptides (AMPs). AMPs are 12-50 amino acids long peptides, which represent an essential part in the innate immune system in most organisms. Indeed, they are among the first defensive molecules released during infections and their activity is direct thorough the membrane of bacteria, causing its destruction and consequently the death of the pathogen. Therefore, the ability of AMPs to disrupt biological membranes could be exploited to improve the CPPs escape from the endocytic vesicles in addition to, of course, their application as a novel class of antibiotics. The idea is to conjugate the CPP with a molecule that possess an antimicrobial activity, which can destroy the vesicle membrane, and help the complex to reach its target once it has been internalized in the cell. On this ground, the first project I carried out regards the study of a novel chimeric peptide, CM18-Tat11, composed of the antimicrobial peptide CM18 (a cecropin-mellitin hybrid peptide) linked to the cell-penetrating peptide Tat11 (derived from the basic domain of HIV-1 Tat protein). In particular, I investigated the membrane perturbing activity of this peptide (and of its elements) using the patch-clamp technique and operating under strictly physiological conditions. This study has been carried out by recording the ion current flowing through the channels formed by these peptides (if any), once inserted in the membrane of Chinese hamster ovary (CHO) cells. In these experiments, the peptides were applied to (and removed from) the extracellular CHO membrane in ~50 ms with a
computer-controlled microperfusion system. Therefore, besides assessing ion channel characteristics, the dynamics of pore formation and disaggregation could be precisely evaluated as well. I found that CM18-Tat11 produces a large and irreversible plasma membrane lysis, at concentration where CM18 and Tat11 give instead a nearly reversible membrane permeabilization and no perturbation, respectively. Furthermore, using the same method, I studied the biophysical characteristic of another antimicrobial peptide, called CM12, which sequence was obtained from the optimization of CM18. When applied on CHO, CM12 and CM18 produce voltage-independent membrane permeabilization, and no single-channel events were detected at low peptides concentration. These results indicate that both peptides form pores according to a toroidal model, in which the lipid layer bends continuously through the pore so that the core is formed by both lipid head groups and the peptides. Finally, I have studied the single-channels properties generated by the pore-forming peptide alamethicin (Alm) F50/5 and its [L-Glu(OMe)7,18,19] analog inserted in a natural membrane and in giant unilamellar vesicles (GUVs). The possibility to compare the channel activity in the precisely controlled lipid environment of GUVs, with the one recorded in a natural membrane, will open new possibilities in the biophysical characterization of the pores.
The second project of this thesis is focused on the study of the physiological role of the calcium sensor GCAP3 (guanylate cyclase activated protein 3) in the phototransduction cascade in zebrafish. I pursued this study simulating the over expressions and the knockdown of this protein, through the delivery of zGCAP3, or of its monoclonal antibody, into zebrafish cone cytoplasm, while recording their photorensponses with the patch-clamp technique. The proteins were administered inside the cone via the patch pipette thanks to an intracellular perfusion system developed in this thesis. This system allows the delivery of exogenous molecules inside the cell with a controlled timing, by expelling them with a small teflon tube inserted into the pipette lumen controlled by a microperfusion apparatus. Results indicated that the increase in the concentration in zGCAP3 did not altered significantly the light response, while the perfusion with the antibody anti-zGCAP3 caused the progressive fall of the dark current, together with the progressive slowing down of the flash response kinetics. The surprising lack of an effect of zGCAP3 incorporation, suggests that the endogenous number of zGCAP3 is saturating, therefore any further increase of this sensor is ineffective. However, the effects of the antibody can be explained as an inhibition of the target enzyme of zGCAP3, which is the guanylate cyclase (GC).
Finally, no experiments mentioned above would have been accomplished without the development of a “pressure-polishing” system, which makes it possible to modify the geometry of the patch-clamp pipette. The pipette shank (the final part of the pipette) is, in fact, very long and tapered, thus generating a high resistance to the passage of ions and molecules, and making very difficult to perfuse efficiently the cell with the internal perfusion. The pressure polishing setup I developed enlarged the patch pipette shank, using a calibrated combination of heat and air pressure. These pipettes minimized errors in membrane potential control and allowed the insertion of teflon tubes in the pipette lumen very close to its tip.
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Zerfas, Breanna L. « Creating Novel Antimicrobial Peptides : From Gramicidin A to Screening a Cyclic Peptide Library ». Thesis, Boston College, 2017. http://hdl.handle.net/2345/bc-ir:107444.
Texte intégralRésumé :
Thesis advisor: Jianmin GaoAs the threat of microbial resistance to antibiotics grows, we must turn in new directions to find new drugs effective against resistant infections. Antimicrobial peptides (AMPs) and host-defense peptides (HDPs) are a class of natural products that have been well-studied towards this goal, though very few have found success clinically. However, as there is much known about the behavior of these peptides, work has been done to manipulate their sequences and structures in the search for more drug-like properties. Additionally, novel sequences and structures mimicking those seen in nature have been discovered and characterized. Herein, we demonstrate our ability to finely tune the antimicrobial activity of various peptides, such that they can be provided with more clinically desirable characteristics. Our results show that gramicidin A (gA) can be made to be less toxic via incorporation of unnatural cationic amino acids. This is achieved by synthesizing lysine analogues with diverse hydrophobic groups alkylated to the side-chain amine. Through exploring different groups, we achieved peptide structures with improved selectivity for bacterial over mammalian membranes. Additionally, we were able to achieve novel broad-spectrum gram-negative activity for gA peptides. In efforts to combat bacterial resistance to cationic antimicrobial peptides (CAMPs), we have directed our reported amine-targeting iminoboronate chemistry towards neutralizing Lys-PG in bacterial membranes. Originally incorporating 2-APBA into gA, we found this to hinder the peptide’s activity. However, we were successful in increasing the potency of gA3R, a cationic mutant of gA, towards S. aureus by using a co-treatment of this peptide with a Lys-PG binding structure. Currently, we are exploring this strategy further. Finally, we describe our work towards establishing a novel cyclic peptide library incorporating a 2-APBA warhead for iminoboronate formation with a given target. In this, we have achieved intermolecular reduction of iminoboronates, strengthening the stringency of library screening. Although we were unsuccessful in finding a potent hit for binding of the lipid II stem peptide, screening against human transferrin yielded selective hits. Currently we are investigating these hits to understand their activity and therapeutic potential
Thesis (PhD) — Boston College, 2017
Submitted to: Boston College. Graduate School of Arts and Sciences
Discipline: Chemistry
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Borrelli, Alexander P. « Synthetic Genes for Antimicrobial Peptides ». Digital WPI, 2003. https://digitalcommons.wpi.edu/etd-theses/427.
Texte intégralRésumé :
The goal of this project was to clone and express the antimicrobial peptide protegrin 1 (PG-1). Initially a yeast system was chosen but was discarded due to technical difficulties. Invitrogen's bacterial T7 expression system was chosen next to express the peptide. PG-1 expression was verified by anti-his immunoblot and then the peptide was purified by IMAC. Its activity was verified using a Bacillus subtillis radial diffusion assay.
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Jodoin, Joelle. « Histone H5 : Bioinspiration for Novel Antimicrobial Peptides ». Thesis, Université d'Ottawa / University of Ottawa, 2017. http://hdl.handle.net/10393/36976.
Texte intégralRésumé :
Modern medicine is challenged continuously by the increasing prevalence of multi-drug resistant bacteria. Therefore, the development of alternatives to traditional antibiotics is an urgent necessity. Cationic antimicrobial peptides (CAMPs) are components of the innate immune defense system. Histones, generally known as proteins that package and regulate the transcription of DNA, share all of the essential antimicrobial traits of CAMPs, and could be promising alternatives to antibiotics. In this study, I investigated the antimicrobial properties of nucleated-erythrocyte-specific linker histone H5 and its derived peptides. Histone H5 was extracted and purified from chicken erythrocytes using an acid extraction followed by ion exchange chromatography using a step salt gradient; the purity (>95%) was verified by densitometry and proteomics analysis. Purified histone H5 demonstrated potent antimicrobial activity against various Gram-positive and Gram-negative planktonic bacteria, including resistant strains such as methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus (VRE), as well as anti-biofilm activity against Listeria monocytogenes and Pseudomonas aeruginosa. Furthermore, scanning electron microscopy (SEM) revealed significant damage to L. monocytogenes and P. aeruginosa bacterial cell surfaces after histone H5 treatment. The potential for histone toxicity towards mammalian cells was investigated with a hemolytic assay which determined that even at the highest concentration tested (1 mg/mL), histone H5 was non-hemolytic. An in silico analysis determined the predicted antimicrobial domain of histone H5 of which six histone H5-derived peptides with potential antimicrobial activity were identified. These six histone H5-derived peptides were synthesized and tested against bacterial pathogens to determine their antimicrobial properties. Although the H5-derived peptides were identified within the predicted antimicrobial domain of histone H5, they did not possess more potent antimicrobial activity than the full length protein. Overall, this study demonstrates that histone H5 and histone H5-derived peptides could be promising candidates in the development of novel anti-infective therapeutics.
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Linser, Sebastian. « Development of new antimicrobial peptides based on the synthetic peptide NK-2 ». [S.l.] : [s.n.], 2006. http://deposit.ddb.de/cgi-bin/dokserv?idn=982021631.
Texte intégralLivres sur le sujet "Antimicrobial peptid"
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Joan, Marsh, Goode Jamie, Ciba Foundation et Symposium on Antimicrobial Peptides (1994 : Ciba Foundation)d), dir. Antimicrobial peptides. Chichester, Eng : Wiley, 1994.
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Hansen, Paul R., dir. Antimicrobial Peptides. New York, NY : Springer New York, 2017. http://dx.doi.org/10.1007/978-1-4939-6737-7.
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Matsuzaki, Katsumi, dir. Antimicrobial Peptides. Singapore : Springer Singapore, 2019. http://dx.doi.org/10.1007/978-981-13-3588-4.
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Phoenix, David A., Sarah R. Dennison et Frederick Harris. Antimicrobial Peptides. Weinheim, Germany : Wiley-VCH Verlag GmbH & Co. KGaA, 2013. http://dx.doi.org/10.1002/9783527652853.
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Giuliani, Andrea, et Andrea C. Rinaldi, dir. Antimicrobial Peptides. Totowa, NJ : Humana Press, 2010. http://dx.doi.org/10.1007/978-1-60761-594-1.
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Harder, Jürgen, et Jens-M. Schröder, dir. Antimicrobial Peptides. Cham : Springer International Publishing, 2016. http://dx.doi.org/10.1007/978-3-319-24199-9.
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Antimicrobial peptides : Methods and protocols. New York : Humana Press/Springer, 2010.
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Drider, Djamel, et Sylvie Rebuffat, dir. Prokaryotic Antimicrobial Peptides. New York, NY : Springer New York, 2011. http://dx.doi.org/10.1007/978-1-4419-7692-5.
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L, Gallo Richard, dir. Antimicrobial peptides in human health and disease. Wymondham, U.K : Horizon Bioscience, 2005.
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Drider, Djamel, et Sylvie Rebuffat. Prokaryotic antimicrobial peptides : From genes to applications. New York : Springer Verlag, 2011.
Trouver le texte intégralChapitres de livres sur le sujet "Antimicrobial peptid"
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Bryskier, A. « Peptide Antibiotics ». Dans Antimicrobial Agents, 826–79. Washington, DC, USA : ASM Press, 2014. http://dx.doi.org/10.1128/9781555815929.ch30.
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Marcos, Jose F., et Paloma Manzanares. « Antimicrobial Peptides ». Dans Antimicrobial Polymers, 195–225. Hoboken, NJ, USA : John Wiley & Sons, Inc., 2011. http://dx.doi.org/10.1002/9781118150887.ch8.
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Park, Andrew J., Jean-Phillip Okhovat et Jenny Kim. « Antimicrobial Peptides ». Dans Clinical and Basic Immunodermatology, 81–95. Cham : Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-29785-9_6.
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Chakraborti, Srinjoy, et Sanjay Ram. « Antimicrobial Peptides ». Dans Management of Infections in the Immunocompromised Host, 95–113. Cham : Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-319-77674-3_5.
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Jack, Ralph W., Gabriele Bierbaum et Hans-Georg Sahl. « Antimicrobial Peptides ». Dans Lantibiotics and Related Peptides, 1–39. Berlin, Heidelberg : Springer Berlin Heidelberg, 1998. http://dx.doi.org/10.1007/978-3-662-08239-3_1.
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Lata, Sneh, et Gajendra Raghava. « Antimicrobial Peptides ». Dans Encyclopedia of Systems Biology, 31–33. New York, NY : Springer New York, 2013. http://dx.doi.org/10.1007/978-1-4419-9863-7_87.
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Ganz, T., et R. I. Lehrer. « Antimicrobial Peptides ». Dans Handbook of Experimental Pharmacology, 295–304. Berlin, Heidelberg : Springer Berlin Heidelberg, 2003. http://dx.doi.org/10.1007/978-3-642-55742-2_16.
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Sørensen, Ole E. « Antimicrobial Peptides in Cutaneous Wound Healing ». Dans Antimicrobial Peptides, 1–15. Cham : Springer International Publishing, 2015. http://dx.doi.org/10.1007/978-3-319-24199-9_1.
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Zasloff, Michael. « Antimicrobial Peptides : Do They Have a Future as Therapeutics ? » Dans Antimicrobial Peptides, 147–54. Cham : Springer International Publishing, 2015. http://dx.doi.org/10.1007/978-3-319-24199-9_10.
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Garreis, Fabian, Martin Schicht et Friedrich Paulsen. « Antimicrobial Peptides as Endogenous Antibacterials and Antivirals at the Ocular Surface ». Dans Antimicrobial Peptides, 17–32. Cham : Springer International Publishing, 2015. http://dx.doi.org/10.1007/978-3-319-24199-9_2.
Texte intégralActes de conférences sur le sujet "Antimicrobial peptid"
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Reinoso, Zain Sanchez, Jacinthe Thibodeau, Laila Ben Said, Ismail Fliss, Laurent Bazinet et Sergey Mikhaylin. « Bioactive Peptide Production from Slaughterhouse Blood Proteins : Impact of Pulsed Electric Fields and Ph on Enzyme Inactivation, Antimicrobial and Antioxidant Activities of Peptic Hydrolysates from Bovine and Porcine Hemoglobins ». Dans 2022 AOCS Annual Meeting & Expo. American Oil Chemists' Society (AOCS), 2022. http://dx.doi.org/10.21748/fsht2150.
Texte intégralRésumé :
Slaughterhouse blood is a valuable by-product since multiple bioactive compounds can be derived out of it. Its solid fraction consists mainly of hemoglobin, which is a good source of antimicrobial and antioxidant peptides that can be released by peptic hydrolysis. Nevertheless, this method has limitations such as low yield, expensive cost of enzyme process, and non-eco-friendly production (high energy consumption and chemical reagents requested). Amount the alternative green technologies for protein valorization, pulsed electric field (PEF) stands out since it allows modifying the physicochemical properties of proteins, promoting the enzymatic hydrolysis, enzyme inactivation, and bioactivity enhancement. Thus, this study aimed to evaluate the effect of PEF on the pepsin inactivation and biological activities (antimicrobial and antioxidant) in hemoglobin hydrolysates. Bovine and porcine hemoglobins were hydrolyzed with pepsin for 3 h (37°C, pH 3.0) and treated with PEF (73 pulses, 23.8kV/cm, 90Hz) to inactivate the enzyme. The hydrolysis degree was evaluated, which did not show significant changes after PEF-inactivation of pepsin, whereas the peptide population analysis by RP-UPLC-MS/MS showed some changes in PEF-treated hydrolysates over time, which suggested a residual pepsin activity. Additionally, the impact of pH (3, 7, and 10) on bioactivity was studied. PEF-treatments did not show a significant impact on antimicrobial (antibacterial, antifungal, and anti-yeast activities) and antioxidant activities (DPPH and ORAC). However, higher pH fostered stronger anti-yeast activity (R. mucilaginosa) and DPPH‐scavenging capacity, whereas pH 7 fostered the antifungal activity (M. racemosus). Even though some changes were observed in the peptide population, no negative effects of PEF were found for biological activities. Thus, the utilization of hemoglobin from the meat industry combined with PEF-treatment fits the circular economy concept since derived peptides can be recycled to protect meat and other products against microbial growth and oxidation.
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Soares, Jason W., et Charlene M. Mello. « Antimicrobial peptides : a review of how peptide structure impacts antimicrobial activity ». Dans Optical Technologies for Industrial, Environmental, and Biological Sensing, sous la direction de Bent S. Bennedsen, Yud-Ren Chen, George E. Meyer, Andre G. Senecal et Shu-I. Tu. SPIE, 2004. http://dx.doi.org/10.1117/12.516171.
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Connolly, John R. F. B., Deirdre Fitzgerald-Hughes et Marc Devocelle. « Novel Antimicrobial Peptide Fluoroquinolone Conjugates ». Dans 36th European Peptide Symposium. The European Peptide Society, 2022. http://dx.doi.org/10.17952/36eps/36eps.2022.062.
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Małuch, Izabela, Oktawian Stachurski, Paulina Kosikowska-Adamus, Dariusz Wyrzykowski, Adam Prahl et Emilia Sikorska. « Double-head lipopeptide surfactants as potential antimicrobial agents ». Dans 35th European Peptide Symposium. Prompt Scientific Publishing, 2018. http://dx.doi.org/10.17952/35eps.2018.153.
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Olkiewicz, Katarzyna, Anna Łegowska, Natalia Ptaszynska, Agata Gitlin-Domagalska, Dawid Debowski, Joanna Okonska, Dorota Martynow, Marcin Serocki, Sławomir Milewski et Krzysztof Rolka. « Peptide conjugates of transportan10 with antimicrobial and antifungal antibiotics ». Dans 35th European Peptide Symposium. Prompt Scientific Publishing, 2018. http://dx.doi.org/10.17952/35eps.2018.309.
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Cantallops-Vilà, Cristina, Laura Colomina-Alfaro, Pietro Riccio, Hanieh Ijakipour, Edwige Meurice, Antonella Bandiera et Artemis Stamboulis. « Different Strategies of Antimicrobial Peptides Production for Biomedical Applications ». Dans 36th European Peptide Symposium. The European Peptide Society, 2022. http://dx.doi.org/10.17952/36eps/36eps.2022.039.
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Garg, Tripti, George Konstantinidis, Joan Peckham, Admir Monteiro, Roxanne LaCroix et Lenore M. Martin. « Designing AMPed : The Practical Antimicrobial Peptide Editable Database ». Dans The 24th American Peptide Symposium. Prompt Scientific Publishing, 2015. http://dx.doi.org/10.17952/24aps.2015.105.
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Turánek, Jaroslav, Michaela Škrabalová et Pavlína Knötigová. « Antimicrobial and anticancer peptides ». Dans XIth Conference Biologically Active Peptides. Prague : Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, 2009. http://dx.doi.org/10.1135/css200911128.
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Plisson, Fabien. « Overcoming the Challenges in Machine Learning-Guided Antimicrobial Peptide Design ». Dans 36th European Peptide Symposium. The European Peptide Society, 2022. http://dx.doi.org/10.17952/36eps/36eps.2022.207.
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Shine, Conor, Jamie MacLennan, Deirdre Fitzgerald-Hughes et Marc Devocelle. « New Generation of Polyethylene Glycol (PEG)-Based Peptidomimetics of Antimicrobial Peptides (AMPs) ». Dans 36th European Peptide Symposium. The European Peptide Society, 2022. http://dx.doi.org/10.17952/36eps/36eps.2022.086.
Texte intégralRapports d'organisations sur le sujet "Antimicrobial peptid"
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Vouros, Paul, et Terrance Black. Solid Phase Peptide Synthesis of Antimicrobial Peptides for cell Binding Studies : Characterization Using Mass Spectrometry. Fort Belvoir, VA : Defense Technical Information Center, novembre 2002. http://dx.doi.org/10.21236/ada412571.
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Doherty, Laurel A., Morris Slutsky et Jason W. Soares. Antimicrobial Peptides with Differential Bacterial Binding Characteristics. Fort Belvoir, VA : Defense Technical Information Center, mars 2013. http://dx.doi.org/10.21236/ada577726.
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Mierswa, S. C., T. H. Lee et M. C. Yung. Developing an engineered therapeutic microbe to release antimicrobial peptides (AMPs). Office of Scientific and Technical Information (OSTI), août 2019. http://dx.doi.org/10.2172/1558856.
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Yung, M. C. Engineering a therapeutic microbe for site-of-infection delivery of encapsulated antimicrobial peptides (AMPs). Office of Scientific and Technical Information (OSTI), octobre 2019. http://dx.doi.org/10.2172/1573149.
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Noga, Edward J., Angelo Colorni, Michael G. Levy et Ramy Avtalion. Importance of Endobiotics in Defense against Protozoan Ectoparasites of Fish. United States Department of Agriculture, septembre 2003. http://dx.doi.org/10.32747/2003.7586463.bard.
Texte intégralRésumé :
Infectious disease is one of the most serious causes of economic loss in all sectors of aquaculture. There is a critical need to understand the molecular basis for protection against infectious disease so that safer, more reliable and more cost-effective strategies can be designed for their control. As part of this effort, the major goal of our BARD project was to determine the importance of endobiotics as a defense against protozoan ectoparasites in fish. Endobiotics, or antimicrobial polypeptides, are peptides and small proteins that are increasingly recognized as having a vital role in the innate defense of virtually all animals. One objective of our BARD project was to determine the antiparasitic potency of one specific group of endobiotics that were isolated from hybrid striped bass (Morone saxatilis x M chrysops). We found that these endobiotics, which we had previously named histone-like proteins (HLPs), exhibited potent activity against Amyloodinium and that the putative levels of HLPs in the skin were well within the levels that we found to be lethal to the parasite in vitro. We also found evidence for the presence of similar antibiotics in sea bream (Sparus aurata) and Mediterranean sea bass (Dicentrarchus labrax). We also examined the effect of chronic stress on the expression of HLP in fish and found that HLP levels were dramatically decreased after only one week of a crowding/high ammonia sublethal stress. We also began to explore the feasibility of upregulating endobiotics via immunostimulation. However, we did not pursue this objective as fully as we originally intended because we spent a much larger effort than originally anticipated on the last objective, the attempted isolation of novel endobiotics from hybrid striped bass. In this regard, we purified and identified four new peptide endobiotics. These endobiotics, which we have named piscidins (from "Pisces" meaning fish), have potent, broad-spectrum activity against a number of both fish and human pathogens. This includes not only parasites but also bacteria. We also demonstrated that these peptides are present in the mast cell. This was the first time that the mast cell, the most common tissue granulocyte in vertebrates, was shown to possess any type of endobiotic. This finding has important implications in explaining the possible function of mast cells in the immune response of vertebrates. In summary, the research we have accomplished in this BARD project has demonstrated that endobiotics in fish have potent activity against many serious pathogens in aquaculture and that there is considerable potential to use these compounds as stress indicators in aquaculture. There is also considerable potential to use some of these compounds in other areas of medicine, including treatment of serious infectious diseases of humans and animals.
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Reisch, Bruce, Avichai Perl, Julie Kikkert, Ruth Ben-Arie et Rachel Gollop. Use of Anti-Fungal Gene Synergisms for Improved Foliar and Fruit Disease Tolerance in Transgenic Grapes. United States Department of Agriculture, août 2002. http://dx.doi.org/10.32747/2002.7575292.bard.
Texte intégralRésumé :
Original objectives . 1. Test anti-fungal gene products for activity against Uncinula necator, Aspergillus niger, Rhizopus stolonifer and Botrytis cinerea. 2. For Agrobacterium transformation, design appropriate vectors with gene combinations. 3. Use biolistic bombardment and Agrobacterium for transformation of important cultivars. 4. Characterize gene expression in transformants, as well as level of powdery mildew and Botrytis resistance in foliage of transformed plants. Background The production of new grape cultivars by conventional breeding is a complex and time-consuming process. Transferring individual traits via single genes into elite cultivars was proposed as a viable strategy, especially for vegetatively propagated crops such as grapevines. The availability of effective genetic transformation procedures, the existence of genes able to reduce pathogen stress, and improved in vitro culture methods for grapes, were combined to serve the objective of this proposal. Effective deployment of resistance genes would reduce production costs and increase crop quality, and several such genes and combinations were used in this project. Progress The efficacy of two-way combinations of Trichoderma endochitinase (CHIT42), synthetic peptide ESF12 and resveratrol upon the control of growth of Botrytis cinerea and Penicillium digitatum were evaluated in vitro. All pairwise interactions were additive but not synergistic. Per objective 2, suitable vectors with important gene combinations for Agrobacterium transformation were designed. In addition, multiple gene co-transformation by particle bombardment was also tested successfully. In New York, transformation work focused on cultivars Chardonnay and Merlot, while the technology in Israel was extended to 41B, R. 110, Prime, Italia, Gamay, Chardonnay and Velika. Transgenic plant production is summarized in the appendix. Among plants developed in Israel, endochitinase expression was assayed via the MuchT assay using material just 1-5 days after co-cultivation. Plants of cv. Sugraone carrying the gene coding for ESF12, a short anti-fungal lytic peptide under the control of the double 358 promoter, were produced. Leaf extracts of two plants showed inhibition zones that developed within 48 h indicating the inhibitory effect of the leaf extracts on the six species of bacteria. X fastidiosa, the causal organism of Pierce's disease, was very sensitive to leaf extracts from ESF12 transformed plants. Further work is needed to verify the agricultural utility of ESF12 transformants. In New York, some transformants were resistant to powdery mildew and Botrytis fruit rot. Major conclusions, solutions, achievements and implications The following scientific achievements resulted from this cooperative BARD project: 1. Development and improvement of embryogenesis and tissue culture manipulation in grape, while extending these procedures to several agriculturally important cultivars both in Israel and USA. 2. Development and improvement of novel transformation procedures while developing transformation techniques for grape and other recalcitrant species. 3. Production of transgenic grapevines, characterization of transformed vines while studying the expression patterns of a marker gene under the control of different promoter as the 35S CaMV in different part of the plants including flowers and fruits. 4. Expression of anti-fungal genes in grape: establishment of transgenic plants and evaluation of gene expression. Development of techniques to insert multiple genes. 5. Isolation of novel grape specific promoter to control the expression of future antimicrobial genes. It is of great importance to report that significant progress was made in not only the development of transgenic grapevines, but also in the evaluation of their potential for increased resistance to disease as compared with the non engineered cultivar. In several cases, increased disease resistance was observed. More research and development is still needed before a product can be commercialized, yet our project lays a framework for further investigations.
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Droby, Samir, Michael Wisniewski, Martin Goldway, Wojciech Janisiewicz et Charles Wilson. Enhancement of Postharvest Biocontrol Activity of the Yeast Candida oleophila by Overexpression of Lytic Enzymes. United States Department of Agriculture, novembre 2003. http://dx.doi.org/10.32747/2003.7586481.bard.
Texte intégralRésumé :
Enhancing the activity of biocontrol agents could be the most important factor in their success in controlling fruit disease and their ultimate acceptance in commercial disease management. Direct manipulation of a biocontrol agent resulting in enhancement of diseases control could be achieved by using recent advances in molecular biology techniques. The objectives of this project were to isolate genes from yeast species that were used as postharvest biocontrol agents against postharvest diseases and to determine their role in biocontrol efficacy. The emphasis was to be placed on the yeast, Candida oleophila, which was jointly discovered and developed in our laboratories, and commercialized as the product, Aspire. The general plan was to develop a transformation system for C . oleophila and either knockout or overexpress particular genes of interest. Additionally, biochemical characterization of the lytic peptides was conducted in the wild-type and transgenic isolates. In addition to developing a better understanding of the mode of action of the yeast biocontrol agents, it was also our intent to demonstrate the feasibility of enhancing biocontrol activity via genetic enhancement of yeast with genes known to code for proteins with antimicrobial activity. Major achievements are: 1) Characterization of extracellular lytic enzymes produced by the yeast biocontrol agent Candida oleophila; 2) Development of a transformation system for Candida oleophila; 3) Cloning and analysis of C.oleophila glucanase gene; 4) Overexpression of and knockout of C. oleophila glucanase gene and evaluating its role in the biocontrol activity of C. oleophila; 5) Characterization of defensin gene and its expression in the yeast Pichiapastoris; 6) Cloning and Analysis of Chitinase and Adhesin Genes; 7) Characterization of the rnase secreted by C . oleophila and its inhibitory activity against P. digitatum. This project has resulted in information that enhanced our understanding of the mode of action of the yeast C . oleophila. This was important step towards enhancing the biocontrol activity of the yeast. Fungal cell wall enzymes produced by the yeast antagonist were characterized. Different substrates were identified to enhance there production in vitro. Exo-b-1, 3 glucanase, chitinase and protease production was stimulated by the presence of cell-wall fragments of Penicillium digitatum in the growing medium, in addition to glucose. A transformation system developed was used to study the role of lytic enzymes in the biocontrol activity of the yeast antagonist and was essential for genetic manipulation of C . oleqphila. After cloning and characterization of the exo-glucanase gene from the yeast, the transformation system was efficiently used to study the role of the enzyme in the biocontrol activity by over-expressing or knocking out the activity of the enzyme. At the last phase of the research (still ongoing) the transformation system is being used to study the role of chitinase gene in the mode of action. Knockout and over expression experiments are underway.
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Cytryn, Eddie, Mark R. Liles et Omer Frenkel. Mining multidrug-resistant desert soil bacteria for biocontrol activity and biologically-active compounds. United States Department of Agriculture, janvier 2014. http://dx.doi.org/10.32747/2014.7598174.bard.
Texte intégralRésumé :
Control of agro-associated pathogens is becoming increasingly difficult due to increased resistance and mounting restrictions on chemical pesticides and antibiotics. Likewise, in veterinary and human environments, there is increasing resistance of pathogens to currently available antibiotics requiring discovery of novel antibiotic compounds. These drawbacks necessitate discovery and application of microorganisms that can be used as biocontrol agents (BCAs) and the isolation of novel biologically-active compounds. This highly-synergistic one year project implemented an innovative pipeline aimed at detecting BCAs and associated biologically-active compounds, which included: (A) isolation of multidrug-resistant desert soil bacteria and root-associated bacteria from medicinal plants; (B) invitro screening of bacterial isolates against known plant, animal and human pathogens; (C) nextgeneration sequencing of isolates that displayed antagonistic activity against at least one of the model pathogens and (D) in-planta screening of promising BCAs in a model bean-Sclerotiumrolfsii system. The BCA genome data were examined for presence of: i) secondary metabolite encoding genes potentially linked to the anti-pathogenic activity of the isolates; and ii) rhizosphere competence-associated genes, associated with the capacity of microorganisms to successfully inhabit plant roots, and a prerequisite for the success of a soil amended BCA. Altogether, 56 phylogenetically-diverse isolates with bioactivity against bacterial, oomycete and fungal plant pathogens were identified. These strains were sent to Auburn University where bioassays against a panel of animal and human pathogens (including multi-drug resistant pathogenic strains such as A. baumannii 3806) were conducted. Nineteen isolates that showed substantial antagonistic activity against at least one of the screened pathogens were sequenced, assembled and subjected to bioinformatics analyses aimed at identifying secondary metabolite-encoding and rhizosphere competence-associated genes. The genome size of the bacteria ranged from 3.77 to 9.85 Mbp. All of the genomes were characterized by a plethora of secondary metabolite encoding genes including non-ribosomal peptide synthase, polyketidesynthases, lantipeptides, bacteriocins, terpenes and siderophores. While some of these genes were highly similar to documented genes, many were unique and therefore may encode for novel antagonistic compounds. Comparative genomic analysis of root-associated isolates with similar strains not isolated from root environments revealed genes encoding for several rhizospherecompetence- associated traits including urea utilization, chitin degradation, plant cell polymerdegradation, biofilm formation, mechanisms for iron, phosphorus and sulfur acquisition and antibiotic resistance. Our labs are currently writing a continuation of this feasibility study that proposes a unique pipeline for the detection of BCAs and biopesticides that can be used against phytopathogens. It will combine i) metabolomic screening of strains from our collection that contain unique secondary metabolite-encoding genes, in order to isolate novel antimicrobial compounds; ii) model plant-based experiments to assess the antagonistic capacities of selected BCAs toward selected phytopathogens; and iii) an innovative next-generation-sequencing based method to monitor the relative abundance and distribution of selected BCAs in field experiments in order to assess their persistence in natural agro-environments. We believe that this integrated approach will enable development of novel strains and compounds that can be used in large-scale operations.