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Littérature scientifique sur le sujet « Pteridine Pteridine »

Auteur : Grafiati

Publié le 4 juin 2021

Mis à jour le 14 février 2022

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Articles de revues sur le sujet "Pteridine Pteridine"

1

Mclntyre, G. S., and R. H. Gooding. "Variation in the pteridine content in the heads of tsetse flies (Diptera: Glossinidae: Glossina Wiedemann): evidence for genetic control." Canadian Journal of Zoology 74, no. 4 (1996): 621–26. http://dx.doi.org/10.1139/z96-071.

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The pteridine content of the head capsule of teneral flies from 11 genetically selected lines (including eye-color mutants) of Glossina morsitans morsitans Westwood and Glossina palpalis palpalis Robineau-Desvoidy was examined using fluorescence spectroscopy. Wild-type G. p. palpalis had a greater pteridine content than did wild-type G. m. morsitans. Within G. m. morsitans there was a 25% variation in fluorescence values between genetic lines. Wild-type G. p. palpalis had the same pteridine content as brick mutants but more than tan mutants; in G. m. morsitans the salmon mutants had a higher pteridine content than did wild-type flies. Pteridine content did not account for the difference in eye color between male and female brick mutants. Accumulation of pteridines was not influenced by genotype in young flies, but in older flies salmon mutants accumulated pteridines more rapidly than did wild-type flies. Young flies, both wild type and salmon, accumulated pteridines more rapidly than did old flies. The results of the analysis of head capsule fluorescence in males from the parental lines and F1 and F2 generations of reciprocal crosses of the G. m. morsitans lines with the highest and lowest pteridine contents revealed that genetic control of pteridine content lies on the X chromosome and on one autosome.

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Burton, Casey, and Yinfa Ma. "The role of urinary pteridines as disease biomarkers." Pteridines 28, no. 1 (2017): 1–21. http://dx.doi.org/10.1515/pterid-2016-0013.

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AbstractPteridines and their derivatives function as intermediates in the metabolism of several vitamins and cofactors, and their relevance to disease has inspired new efforts to study their roles as disease biomarkers. Recent analytical advances, such as the emergence of sensitive mass spectrometry techniques, new workflows for measuring pteridine derivatives in their native oxidation states and increased multiplexing capacities for the simultaneous determination of many pteridine derivatives, have enabled researchers to explore the roles of urinary pteridines as disease biomarkers at much lower levels with greater accuracy than with previous technologies or methods. As a result, urinary pteridines are being increasingly studied as putative cancer biomarkers with promising results being reported from exploratory studies. In addition, the role of urinary neopterin as a universal biomarker for immune system activation is being investigated in new diseases where it is anticipated to become a useful supplementary marker in clinical diagnostic settings. In summary, this review provides an overview of recent developments in the clinical study of urinary pteridines as disease biomarkers, covers the most promising aspects of advanced analytical techniques being developed for the determination of urinary pteridines and discusses the major challenges associated with implementing pteridine biomarkers in clinical laboratory settings.

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Goldberg, M., F. Gassner, and M. Merkenschlager. "Studies and Comparison of Urinary Pteridine Patterns in Dogs and Cats and their Alteration in Various Neoplasias and Virus Infections." Pteridines 1, no. 1 (1989): 29–35. http://dx.doi.org/10.1515/pteridines.1989.1.1.29.

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Summary Urinary excretion levels of five pteridines in healthy cats and dogs and in 14 groups of animals with tumours or virus infections were determined by HPLC after partial purification by ion exchange chromatography. Healthy cats and dogs produce species specific differences. In contrary to cats 6-hydroxymethylpterin was not detectable in dogs. Whereas in dogs biopterin presents the main part of pteridines (about 70%), cats contain about 53% catabolic isoxanthopterin in the pteridine pattern. In the various tumours no qualitative but quantitative alterations in the pteridine concentrations could be detected. The changes in the different tumours were not applied to all pteridines, so that each type of tumour shows an own pattern of pteridines.In the parvovirosis of the dog neopterin, biopterin and isoxanthopterin increased significantly. In the virusfree parvovirosis suspicious dogs only pterin was elevated. In the feline leucosis and feline infectious peritonitis a significant rise of all five measured pteridines were observed.Altogether, the data show, that increased urinary pteridines present a real additional aid for the suspicion of neoplasias or viral infections in the veterinary medicine.

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Girgin, Gözde, Terken Baydar, Dietmar Fuchs, Gönül Sahin, Elif Özmert, and Kadriye Yurdakök. "Evaluation of Serum and Urinary Levels of some Pteridine Pathway Components in Healthy Turkish Children." Pteridines 23, no. 1 (2012): 90–95. http://dx.doi.org/10.1515/pteridines.2012.23.1.90.

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Abstract Neopterin, as a non-conjugated pteridine, is synthesized from guanosine triphosphate and its production is upregulated upon the activation of cellular immune response. Alterations of pteridines in body fluids are known to correlate well with existing diseases and stages, prognosis, clinical outcomes and survival data. It is of advantage to have a pteridine database of healthy volunteers to determine normal values. Thereby, especially in children there is no detailed study on pteridine levels. The aim of this study is to initiate the establishment of pteridine database of healthy children in our country. Serum neopterin levels were analysed by enzyme-linked immunosorbent assay. Urinary neopterin and biopterin levels and serum kynurenine, tryptophan levels and kynurenine/tryptophan ratio as an estimate of tryptophan breakdown were assessed with high-pressure liquid chromatography in serum and urine samples of 55 children aged between 3 months and 10 years. The results were evaluated within the subgroups of different ages and sex. Pteridine pathway components were found to be higher in children compared to adults. Higher levels of pteridine pathway components observed within the first years of life may reflect the rapid maturation of the immune system, and environmental adaptation and/or insufficiency of defence systems. On the other hand, it may also relate to a higher frequency of infections not (yet) manifested clinically.

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Soyka, Rainer, and Wolfgang Pfleiderer. "Pteridines, XCVI. Synthesis and Reactions of 6-(1,2,3-Trihydroxypropyl)pteridines." Pteridines 2, no. 2 (1990): 63–74. http://dx.doi.org/10.1515/pteridines.1990.2.2.63.

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Summary Various hydropyrano [3.2-g] pteridines (7, 10, 12, 21 , 33) were oxidized to the corresponding 6-(1,2,3- trihydroxypropyl)pteridine derivatives (8,9, 11, 13,32, 34), which are valuable intermediates for the synthesis of new 6-substituted pteridines (15 - 46). Periodate oxidation led to pteridine-6-carboxaldehydes (15, 16, 17, 38), which easily formed oximes (19 - 22, 39, 40). The aldehydes were further oxidized to 6-carboxylic acids (25,26,42) or reduced to 6-hydroxymethyl derivatives (27, 28, 43). Reductive condensations of the aldehydes (15, 16, 38) with p-aminobenzoylglutamic acid afforded folic acid analogues (29, 30, 44). Dehydration of the oximes (19, 20, 39) resulted in the formation of 6-carbonitriles (23, 24, 41, 46). The newly synthesized compounds were characterized by elemental analysis and by UV and NMR spectra.

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Rinkevich, Frank D., Joseph W. Margotta, Jean M. Pittman, James A. Ottea, and Kristen B. Healy. "Pteridine levels and head weights are correlated with age and colony task in the honey bee,Apis mellifera." PeerJ 4 (June 30, 2016): e2155. http://dx.doi.org/10.7717/peerj.2155.

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Background.The age of an insect strongly influences many aspects of behavior and reproduction. The interaction of age and behavior is epitomized in the temporal polyethism of honey bees in which young adult bees perform nurse and maintenance duties within the colony, while older bees forage for nectar and pollen. Task transition is dynamic and driven by colony needs. However, an abundance of precocious foragers or overage nurses may have detrimental effects on the colony. Additionally, honey bee age affects insecticide sensitivity. Therefore, determining the age of a set of individual honey bees would be an important measurement of colony health. Pteridines are purine-based pigment molecules found in many insect body parts. Pteridine levels correlate well with age, and wild caught insects may be accurately aged by measuring pteridine levels. The relationship between pteridines and age varies with a number of internal and external factors among many species. Thus far, no studies have investigated the relationship of pteridines with age in honey bees.Methods.We established single-cohort colonies to obtain age-matched nurse and forager bees. Bees of known ages were also sampled from colonies with normal demographics. Nurses and foragers were collected every 3–5 days for up to 42 days. Heads were removed and weighed before pteridines were purified and analyzed using previously established fluorometric methods.Results.Our analysis showed that pteridine levels significantly increased with age in a linear manner in both single cohort colonies and colonies with normal demography. Pteridine levels were higher in foragers than nurses of the same age in bees from single cohort colonies. Head weight significantly increased with age until approximately 28-days of age and then declined for both nurse and forager bees in single cohort colonies. A similar pattern of head weight in bees from colonies with normal demography was observed but head weight was highest in 8-day old nurse bees and there was no relationship of head weight with age of foragers.Discussion.Although the relationship between pteridine levels and age was significant, variation in the data yielded a +4-day range in age estimation. This allows an unambiguous method to determine whether a bee may be a young nurse or old forager in colonies with altered demographics as in the case of single cohort colonies. Pteridine levels in bees do not correlate with age as well as in other insects. However, most studies used insects reared under tightly controlled laboratory conditions, while we used free-living bees. The dynamics of head weight change with age is likely to be due to growth and atrophy of the hypopharyngeal glands. Taken together, these methods represent a useful tool for assessing the age of an insect. Future studies utilizing these methods will provide a more holistic view of colony health.

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Döring, Thomas, Romesh C. Boruah, and Wolfgang Pfleiderer. "Synthesis of 7-Acyl-2,4-disubstituted Pteridines by Radical Nucleophilic Substitution and Displacement Reactions." Pteridines 15, no. 4 (2004): 129–48. http://dx.doi.org/10.1515/pteridines.2004.15.4.129.

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Abstract 2,4-Disubstituted pteridine derivatives (1-3) react with acyl radicals very selectively in position 7 by a nucleophilic Substitution mechanism (4-10). Oxidation of the 2-methylthio group proceeds with m-chloroperbenzoic acid in good yields to the corresponding 7-acyl-2-methylsulfonyl-4-aminopteridines (11-16). The methylsulfonyl group can easily been displaced by nucleophiles such as aliphatic amines (27, 29, 32-42, 45), cyclic amines (56-61), aromatic amines (30, 31) and amino acids (43-54). Oxygen nucleophiles lead to 7-acyl-isopterin derivatives (62-66). The acyl side-chain is also prone to structural modifications leading to the corresponding secondary alcohols on NaBH4 reduction (74-77) or to imino derivatives on reactions with amines (67-73) which can analogously been reduced to 2,4-disubstituted 7-( l-aminoalkyl)pteridines (80-85). An interesting H-shift was observed during heating of 32, 78 and 79 with benzylamine leading not to the benzylimines but the isomeric benzylideneamino derivatives 86-88. Various acetylations by acetic anhydride (AC2O) gave 89-93 and reduction of the pyrazine moiety to the 5,6,7,8-tetrahydro-pteridine derivatives 94-96 proceeded in the expected manner. The characterization of ther newly synthesized pteridine derivatives was performed by 1H-NMR spectra, UV-spectra and elemental analyses. Measurements of the basic pKa values of a selection of 2,4,7-trisubstituted pteridines were pteridines to characterize the dication, monocation and the neutral species by their UV-spectra.

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Edalat, Hamideh, Mohammad Akhoundi, and Hamidreza Basseri. "Age-dependance of pteridines in the malaria vector, Anopheles stephensi." Pteridines 28, no. 3-4 (2017): 157–61. http://dx.doi.org/10.1515/pterid-2017-0009.

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AbstractDetermining the accurate age of malaria vectors is crucial to measure the risk of malaria transmission. A group of fluorescent chemicals derived from a pyrimidine-pyrazine ring structure known as pteridines from the head, thorax and whole body of adult female Anopheles stephensi were identified and evaluated as a tool for chronological and physiological age determination of malaria vectors. The female mosquitoes were collected from an insectary colony at an interval of every 5 days, up to 30 days, and the pteridines of head, thorax and whole body were detected fluorometrically by high-pressure liquid chromatography (HPLC) using excitation and emission wavelengths of 365 and 455 nm, respectively. In addition, alteration of the pteridines compounds was compared between blood and sugar fed mosquito groups. Although four pteridines including pterin-6-carboxylic acid, biopterin, xanthopterin and isoxanthopterin were detected, some of them were absent in the head or thorax of mosquitoes. Levels of all four pteridines were similarly decreased in a linear manner throughout 30 days. No significant difference in alteration of pteridine compounds was observed between the two groups of blood or sugar fed mosquitoes. This result indicates that diet has a little effect on pteridines alteration. Age determination based on pteridines, as an age-grading technique, could be used for field collected mosquitoes, which have either sugar or blood meal. In addition, analyzing total pteridine fluorescence from only whole body could be a convenient method to estimate the age.

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Tsusué, M., S. Kuroda, and H. Sawada. "Localization of Sepiapterin Deaminase and Pteridines In the Granules In Epidermal Cells of the Silkworm, Bombyx mori." Pteridines 2, no. 3 (1990): 175–82. http://dx.doi.org/10.1515/pteridines.1990.2.3.175.

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Summary A new method for assay of sepiapterin deaminase (3.5.4.24) activity by use of high performance liquid chromatography (HPLC) was developed. By this sensitive method the enzyme activity in the cell organelle was assayed. After cell fractionation, the enzyme was extracted with deoxycholate from pteridine granules of epidermal cells of the lemon mutant silkworm. On stepwise sucrose gradient centrifugation, most of the enzyme activity localized in the aggregated pteridine granules fraction, while the soluble fraction contained only one fourth of the total enzyme activity. The enzyme in the granule fraction had the same properties as the previously reported sepiapterin deaminase. These data show that the enzyme is localized in pteridine granules in the living cells. The attachment of the enzyme to the granule membrane is rather loose and previous papers studied the enzyme released from the granules. Cell fractionation and morphological observation showed that sepiapterin, sepialumazine and other pteridines were also localized in the granules together with uric acid.

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Ochoa, C., M. Rodríguez, L. Domínguez, et al. "Nematocide activity of 6,7-diarylpteridines in three experimental models." Journal of Helminthology 73, no. 4 (1999): 333–36. http://dx.doi.org/10.1017/s0022149x99000554.

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Thein vitronematocide activity of seventeen 6,7-diarylpteridines has been tested using three different experimental models,Caenorhabditis elegans,Nippostrongylus brasiliensisandHeligmosomoides polygyrus. The method of evaluation of inhibition in the secretion of acetylcholinesterase byH. polygyrusseems to be the most indicated to avoid false positives. Thein vivoactivities, againstTrichinella spiralis, of the mostin vitroactive pteridines have been assayed. All pteridine derivatives bearing 6,7-di-p-bromophenyl substituents have shownin vitronematocide activites in the three experimental models used. Amongst all the pteridines testedin vivo, only 2,4-pteridinedithione derivatives exhibited moderate activity.

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Thèses sur le sujet "Pteridine Pteridine"

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Rebelo, Jorge Manuel Baeta Simões. "Biosynthesis and function of biological pteridines structural studies on two molybdopterin containing aldehyde oxido-reductases, from Desulfovibrio desulfuricans ATCC 27774 and from Desulfovibrio gigas, and the GTP cyclohydrolase I on E. coli, responsible for the first step of the tetrahydropterin biosynthesis /." [S.l. : s.n.], 2004. http://deposit.ddb.de/cgi-bin/dokserv?idn=972340319.

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Guschin, Dmitrii. "Chemische Modifizierung von Pyranopterinen und deren Metallkomplexe strukturelle Modelle für Zentren in Metalloenzymen /." [S.l.] : [s.n.], 2003. http://deposit.ddb.de/cgi-bin/dokserv?idn=967843537.

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Ekwall, Olov. "Pteridine dependent hydroxylases as autoantigens in autoimmune polyendocrine syndrome type 1." Doctoral thesis, Uppsala : Acta Universitatis Upsaliensis : Univ.-bibl. [distributör], 2001. http://publications.uu.se/theses/91-554-4941-7/.

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Chatelet, Pascal. "Ptéridines non conjuguées et infections neuro-méningées." Lille 2, 1990. http://www.theses.fr/1990LIL2M349.

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Graham, Gordon W. "A study of biochemical genetic abnormalities associated with purine and pteridine metabolism." Thesis, University of Glasgow, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.301808.

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Barrack, Keri L. "Structural examination of trypanosomatid tubulin-binding cofactors and pteridine reductase 1 inhibition." Thesis, University of Dundee, 2013. https://discovery.dundee.ac.uk/en/studentTheses/73141a09-d8c2-4410-8884-3b3d80d1be00.

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Trypanosomatid parasites are the causative agents of neglected tropical diseases for which current therapies are inadequate. As primitive eukaryotic organisms, they also represent a useful model system to investigate fundamental cellular biology while studies of potential drug targets endeavour to develop new drug molecules. Aspects of both of these areas are explored in this thesis. Microtubules are polymers of tubulin and are essential in eukaryotes for cell division, motility and maintenance of cell morphology. Five tubulin-binding cofactors (TBC, named A-E) are proteins implicated in the folding, polymerisation and processing of tubulin, the major component of the trypanosomatid cytoskeleton. At the initiation of this study, there was no structural information available for any trypanosomatid TBC. We therefore sought to investigate these proteins by X-ray crystallography and assess their potential tubulin-interaction capabilities to support the current functional model. The crystal structure of tubulin-binding cofactor A (TBCA) from Leishmania major is presented, determined using diffraction data to 1.9 Å resolution. Prior to tubulin polymerisation, TBCA forms a complex with ß-tubulin in the pathway to aß-tubulin heterodimerisation. It maintains a soluble pool of ß-tubulin and can prevent premature polymerisation. This is a short helical protein, similar in structure to published homologues. The similarities and some distinct local features that may impact on ß-tubulin binding are discussed. In particular, the surface properties of a prominent bend in the helix bundle represents an area that may be capable of interacting with its tubulin partner. Tubulin-binding cofactor C (TBCC) is implicated in stimulating the hydrolysis of GTP bound to ß-tubulin prior to release of the assembly-competent aß-tubulin heterodimer from a supercomplex between TBCC, TBCD, TBCE and both tubulin subunits. Full-length recombinant Trypanosoma brucei and Leishmania major tubulin-binding TBCC were degraded and crystallisation could not be achieved. However, crystals of a truncated TBCC construct were obtained. Despite efforts to optimise crystallisation and diffraction data, the structure was not solved for inclusion in this thesis. Instead, homologous structures were analysed and a potential tubulin interaction site is suggested based on the proposed GTPase-stimulating activity of TBCC and the similarity with the human protein, Retinitis Pigmentosa 2 (RP2), predicted to contain a domain with similar fold. Progress towards the soluble recombinant expression of the other cofactors also lays the foundation for future investigations into trypanosomatid TBC structure and function. Pteridine reductase 1 (PTR1), an enzyme unique to trypanosomatids, is the subject of Part II of this thesis. PTR1 is a broad-spectrum NADPH-dependent reductase, catalysing the two-stage reduction of biopterin to dihydrobiopterin and tetrahydrobiopterin and that of folate to dihydrofolate and tetrahydrofolate. As such, it can provide a bypass mechanism for the reduction of folates, reducing the therapeutic action of traditional antifolate molecules in these organisms. Inhibition of PTR1 is therefore desirable from a drug discovery viewpoint. The crystal structure of Leishmania donovani PTR1 was determined using data extending to 2.5 Å resolution with a view to generating ligand-complex structures and providing a model for inhibitor design. This structure was found to contain a disordered active site, with several loop regions not modelled or relocated. A sulfate molecule from the crystallisation mixture binds in the cofactor phosphate binding-site and the sequential binding of cofactor before substrate or inhibitor can not occur. Although this crystal form was considered unsuitable for further studies, it provides the only structure of PTR1 in the absence of cofactor. With an established crystallisation protocol, Trypanosoma brucei PTR1 then forms the basis of a collaborative investigation of over 100 novel potential inhibitory molecules. Kinetic evaluation, isothermal titration calorimetry (ITC) and co-crystallisation were applied to generate ligand-binding profiles of pyrrolopyrimidine derivatives. Several interesting binding features were identified from the 24 ligand complex structures obtained. These include the discovery of two covalent inhibitors, confirming the reactivity of a non-conserved active site cysteine, and molecules that are able to bind simultaneously at two locations within the active site pocket, exploiting hydrogen-bonding interactions with key catalytic and other nearby residues. The thermodynamic binding profiles of seven inhibitors also provide insight into the enthalpic and entropic contributions to ligand binding. We assessed the suitability of ITC for this system and while a high attrition rate was observed, chemical substitutions were able to enhance the binding entropy. These studies have strengthened our understanding of the structure-activity relationship between PTR1 and inhibitors, offering opportunities to develop new molecules that focus on increasing the potency generated by favourable enthalpy alongside improving the drug-like properties.

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Luba, James. "Studies of Leishmania major Pteridine Reductase 1, a Novel Short Chain Dehydrogenase." eScholarship@UMMS, 1997. https://escholarship.umassmed.edu/gsbs_diss/45.

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Pteridine reductase 1 (PTR1) is an NADPH dependent reductase that catalyzes the reduction of several pterins and folates. The gene encoding this enzyme was originally identified in Leishmania based on its ability to provide resistance to the drug methotrexate (MTX). The DNA and amino acid sequences are known, and overproducing strains of Escherichia coli are available. PTR1 has been previously shown to be required for the salvage of oxidized pteridines (folate, biopterin, and others). Since Leishmaniaare folate and pterin auxotrophes, PTR1 is a possible target for novel anti-folate drugs for the treatment of leishmaniasis. PTR1 catalyzes the transfer of hydride from NADPH to the 2-amino-4-oxo-pteridine ring system yielding 7, 8-dihydropteridines, and to the pteridine ring system of 7, 8-dihydropteridines yielding 5,6, 7, 8-tetrahydropteridines. PTR1 shows a pH dependent substrate specificity. At pH 4.6 the specific activity of PTR1 is highest with pterins, while at pH 6.0 the specific activity of PTR1 was highest with folates. The sequence of PTR1 is only 20-30% homologous to the sequences of members of the short chain dehydrogenase/reductase enzyme family. Although this is typical for members of this enzyme family, it does not allow for unambiguous classification in this family. In fact, when the DNA sequence of PTR1was first determined, PTR1 was classified as an aldoketo reductase. To classify PTR1 definitively, further biochemical characterization was required. To provide this information, the work described here was undertaken: (i) the stereochemical and kinetic course of PTR1 was determined; (ii) residues important in catalysis and ligand binding were identified; and (iii) conditions for the crystallization of PTR1 were developed. The stereochemistry of hydride transfer The use of [3H]-folate, showed that the ultimate product of PTR1 was 5, 6, 7, 8-tetrahydrofolate. 4R-[3H]-NADPH and 4S-[3H]-NADPH were synthesized enzymatically and used as the cofactor for the reduction of folate. PTR1 was coupled to thymidylate synthase (TS), and tritium from 4S-[3H]-NADPH was transferred to thymidylate. Therefore, the pro-S hydride of NADPH was transferred to the si face of dihydrofolate (DHF; see figure I-1). The transfer of the pro-Shydride indicates that PTR1 is a B-side dehydrogenase which is consistent with its membership in the short chain dehydrogenase (SDR) family. The kinetic mechanism of PTR1 When NADPH was varied at several fixed concentrations of folate (and vice-versa) V/K (Vmax/KM) showed a dependence upon concentration of the fixed substrate. This is consistent with a ternary complex mechanism, in contrast to a substituted enzyme mechanism that exhibits no dependence of V/K on fixed substrate. Product inhibition patterns using NADP+ and 5-deazatetrahydrofolate (5dTHF, a stable product analog) were consistent with an ordered ternary complex mechanism in which NADPH binds first and NADP+ dissociates last. However, an enzyme-DHF binary complex was detected by fluorescence. Isotope partitioning experiments showed that the enzyme-DHF binary complex was not catalytically competent whereas the enzyme-NADPH complex was. Measurement of the tritium isotope effect on V/K (T(V/K)) at high and low dihydrofolate confirmed that PTR1 proceeds via a steady state ordered mechanism. Rapid quench analysis showed that dihydrofolate was a transient intermediate during the reduction of folate to tetrahydrofolate and that folate reduction is biphasic. Catalytic Residues of PTR1 The amino acid sequences of dihydropteridine reductase and 3-α, 20-β, hydroxy steroid dehydrogenase were aligned to that of PTR1. Based on the results of the alignment, site directed mutagenesis was used to investigate the role of specific residues in the catalytic cycle of PTR1. Variant enzymes were screened based on their ability to rescue a dihydrofolate reductase (DHFR) deficient strain of E. coli. Selected PTR1 variants (some complementing and some non-complementing) were purified and further characterized. Tyrosine 193 of the wild type enzyme was found to be involved in the reduction of pteridines, but not in the reduction of 7, 8-dihydropteridines, and eliminated the substrate inhibition of 7, 8-dihydropteridines observed with the wild type enzyme. Both PTR1(K197Q) and PTR1(Y193F/K197Q) had decreased activity for all substrates and low affinity for NADPH. In contrast to the wild type enzyme, NADPH displayed substrate inhibition towards PTR1(K197Q). All PTR1(D180) variants that were purified were inactive except for PTR1(D180C), which showed 2.5% of wild type activity with DHF. The binary complexes of PTR1(D180A) and PTR1(D180S) with NADPH showed a decrease in affinity for folate. Based on the kinetic properties of the PTR1 variants, roles for Y193, K197, and D180 are proposed. In conjunction with D180, Y193 acts as a proton donor to N8 of folate. K197 forms hydrogen bonds with NADPH in the active site and lowers the pKaof Y193. D180 participates in the protonation of N8 of folate and N5 of DHF. Crystallization of PTR1 and PTR1-ligand complexes The crystallization of PTR1 from L. major and L. tarentolea as unliganded and as binary and ternary complexes was attempted. Several crystal forms were obtained including L. major PTR1-NADPH-MTX crystals that diffracted to ~ 3.2 Å resolution. It was not possible to collect a full data set of any of the crystals. At their current stage, none of the crystal forms is suitable for structural work.

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Morin, Eric. "La néoptérine : aspects analytiques et physio-pathologiques." Paris 5, 1995. http://www.theses.fr/1995PA05P038.

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Vargas, Lowman Aidamalia. "Les bases génétiques de la pigmentation dans les embryons de punaise d'eau." Thesis, Lyon, 2019. http://www.theses.fr/2019LYSEN042/document.

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Le but de ce doctorat était de comprendre les bases génétiques de la diversification de la pigmentation extra-oculaire chez les embryons des Gerromorphes. La plupart des punaises semi-aquatiques présentent une variabilité de pattern de couleur jaune ou/et rouge dans les pattes et les antennes au stade embryonnaire. La couleur rouge observée dans les appendices étant similaire à celle présente dans les yeux, nous avons émis l'hypothèse que les couleurs extra-oculaires pouvaient être produites par la co-option des voies de synthèse des pigments des yeux. Nous avons d'abord déterminé l'histoire évolutive de ce trait à partir de sa présence ou de son absence dans les embryons de 34 espèces. Grâce à l'analyse génétique par interférence ARN et hybridation in situ, nous avons identifié les voies impliquées dans la pigmentation des yeux et des organes extra-oculaires dans l'espèce Limnogonus franciscanus. Nous avons ensuite testé par interférence ARN et hybridation in situ trois gènes de la voie ptéridine dans cinq autres espèces de Gerromorphes présentant des colorations extra-oculaires différentes. Les résultats suggèrent que la même voie a été recrutée une seule fois pour produire la diversité de pattern. De plus, grâce à une analyse chimique par ultra-chromatographie couplée à de la spectrométrie de masse, nous avons identifié que la xanthopterin et l’erythropterin sont les deux pigments responsables de la couleur chez différentes espèces. Nous nous sommes aussi demandé comment le recrutement d'une seule et même voie conservée pouvait produire une telle diversité de pattern. En utilisant la technologie de transcriptomique du RNA-seq, nous avons identifié 167 facteurs de transcription co-exprimés dans les yeux, les antennes et les pattes des embryons de Limnogonus franciscanus. Ces protéines pourraient intervenir dans la régulation des gènes impliqués dans la formation des patterns de couleur embryonnaire. Nous avons initié un crible ARNi de ces facteurs de transcription. En conclusion, la pigmentation des punaises semi-aquatiques au stade embryonnaire est un bon modèle pour comprendre la co-option des voies génétiques et la question sous-jacente de la façon dont une voie conservée pourrait être réglementée pour produire divers phénotypes<br>The principal aim of this doctoral thesis was to understand the genetic basis for the diversification of the extra-ocular pigmentation in Gerromorpha embryos. Most of the semi-aquatic bugs develop a variability of yellow or red colours patterns in legs and antennas during the embryonic stage. Since the red colour in appendages was similar to the one present in eyes, we hypothesized that the extra-ocular colours could be produced by the co-option of the eye pigments biosynthesis pathway. First we inferred the evolutionary history of this trait based on its presence or absence in embryos of 34 species. We found that the ancestral state of the trait in Gerromorpha was yellow and that six independent lineages evolved bright red colour, while two lineages lost the colour. Using RNAi and in situ hybridisation on homologous genes from the pteridine and ommochrome biosynthesis pathways, we described the genetic pathway involved in the production of pigments in eyes and extra-ocular tissues in Limnogonus franciscanus embryos. After that, we performed a screening of three genes from this pathway in five other species with different extra-ocular colours and patterns. We discovered that the same pathway was recruited once to produce the diversity of patterns in Gerromorpha. Furthermore, we identified by UPLC-HRMS that xanthopterin and erythropterin pigments produce the variability of colours and patterns in different species. Our next step aimed to understand how the recruitment of a conserved pathway could produce this striking diversity of colour patterns. Using RNA-Seq technology and bioinformatics tools, we identified 167 transcription factors that are co-expressed in eyes, antennas and legs of embryos in Limnogonus franciscanus. These proteins might be involved in the regulation of genes responsible for the different colour patterns. We have started an RNAi screen of these transcription factors. This project is still ongoing but in this thesis I will present the preliminary results and conclusions.In conclusion, the pigmentation of semi-aquatic bugs during the embryonic stage is a good model to understand the co-option of pre-existing genetic pathways and underlying the question of how a conserved pathway could be regulated to produce diverse morphological phenotypes

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Martini, Viviane Paula. "DETERMINAÇÃO E ESTUDOS DE ESTRUTURAS DE COMPLEXOS ENZIMALIGANTES RELEVANTES À BIOLOGIA DAS PTERIDINAS EM PARASITAS: BASE PARA O DESENVOLVIMENTO RACIONAL DE DROGAS TERAPÊUTICAS CONTRA DOENÇA DO SONO." UNIVERSIDADE ESTADUAL DE PONTA GROSSA, 2007. http://tede2.uepg.br/jspui/handle/prefix/2124.

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Made available in DSpace on 2017-07-24T19:38:12Z (GMT). No. of bitstreams: 1 VivianePaula.pdf: 3188050 bytes, checksum: 1b1ca9983470b6e6a3669cfd52a8c846 (MD5) Previous issue date: 2007-03-06<br>Coordenação de Aperfeiçoamento de Pessoal de Nível Superior<br>The enzymes dihydrofolate reductase-thymidylate synthase (DHFR-TS) and pteridine reductase (PTR) are involved in the pterin/folate dependent metabolism; together they represent an important target for chemotherapy of parasitic leishmanias and trypanosomes. Xray crystallography was used to elucidate accurately the structure of the PTR1 enzyme from Trypanosoma brucei in complex with inhibitors which are analogous to the substrate. The ligands assayed for crystallization were the substrate folate and the inhibitors melamine, 6-thioguanine, WSG1012, WSG1034, WSG3065, WSG3066 and WSG3067. Of these, four yielded crystals with diffraction patterns sufficient for a complete dataset. WSG3065 (later revealing the lack of the ligand), WSG3066 and WSG3067 are three of the several structures presented in this work which came from the cited crystallization assays; added to these are the refined structures complexed with triamterene and cyromazine, proceeded from two other datasets already available. The datasets were processed with the programs Mosflm / Scala and Xds / Xscale, the structures were refined using the programs CNS and Refmac5 and validated with the programs Procheck, Whatcheck, Sfcheck and ValidationPDB. All refined structures belong to the space group P21 with unit cells around a = 79, b = 90, c = 82, b = 115, 4 monomers each of 268 residues per asymmetric unit and complex active sites. Besides the inhibiting ligands (except WSG3065) present in the structure, other ligands were found either near or outside the active site: dithiothreitol, glycerol, ethylene glycol, sodium and acetate ions. Analyses on the ligand positions and corresponding interactions with the protein were carried out to understand modes of inhibition and to guide the design or the discovery of new compounds which are potent, but selective to the parasitic enzyme, inhibitors. Thereby, initial docking studies were performed aiming at identifying new molecules or lead compounds with inhibitory capabilities.<br>As enzimas dihidrofolato redutase-timidilato sintase (DHFR-TS) e pteridina redutase (PTR) estão envolvidas no metabolismo pterina/folato dependente; juntas, representam um importante alvo para a quimioterapia de leishmanias e tripanossomas parasitas. A Cristalografia por Raios X foi utilizada para elucidar acuradamente a estrutura da enzima PTR1 de Trypanosoma brucei complexada com inibidores que são análogos ao substrato. Os ligantes ensaiados para cristalização foram o substrato folato e os inibidores melamina, 6-tioguanina, WSG1012, WSG1034, WSG3065, WSG3066 e WSG3067. Destes, quatro forneceram cristais com padrões de difração suficientes para um conjunto de dados completo. WSG3065 (mais tarde revelando ausência do ligante), WSG3066 e WSG3067 são três das estruturas apresentadas neste trabalho derivadas dos ensaios de cristalização citados; somadas a estas estão as estruturas refinadas dos complexos com triantereno e ciromazina, provenientes de dois outros conjuntos de dados anteriormente disponíveis. Os conjuntos de dados foram processados com os programas Mosflm / Scala e Xds / Xscale, as estruturas refinadas usando-se os programas CNS e Refmac5 e validadas com os programas Procheck, Whatcheck, Sfcheck e ValidationPDB. Todas as estruturas refinadas apresentaram grupo espacial P21 com celas unitárias aproximadas a = 79 = 90, c = 82 , b = 115, 4 monômeros de 268 resíduos cada por unidade assimétrica e sítios ativos complexos. Além dos ligantes inibidores presentes nas estruturas (exceto WSG3065), outros ligantes foram encontrados próximos ou fora do sítio ativo: ditiotreitol, glicerol, etilenoglicol, íons sódio e íons acetato. Análises das posições dos ligantes inibidores e correspondentes interações com a proteína foram realizadas a fim de se entender modos de inibição e, em particular, assistir ao planejamento ou à descoberta de novos compostos que sejam inibidores potentes, mas seletivos, para a enzima parasitária. Assim, estudos iniciais de atracagem (docking) foram realizados visando identificar novas moléculas ou arcabouços com capacidades inibitórias.

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Livres sur le sujet "Pteridine Pteridine"

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Mohr, Detlef. Synthese, Reaktionen, und Eigenschaften neuer 6- und 7- subtituierter C-S- und C-C- verknüpfter Pteridine: Modellreaktionen für Naturstoffsyntesen. Hartung-Gorre, 1991.

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Brown, D. J. Pteridines. Wiley, 1988.

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Soyka, Rainer. Darstellung und Reaktionen von 6-(Trihydroxypropyl)-5,6-dihydro-pteridinen und 6-Formyl-pteridinen, sowie C-C-Verknüpfungsreaktionen an 6-substituierten 1,3-Dimethyllumazinen. Hartung-Gorre, 1987.

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Leskopf, Werner. Beiträge zur Synthese und Chemie von Acyllumazinen. Hartung-Gorre, 1987.

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Wiesenfeldt, Matthias. Synthese, Struktur und Eigenschaften neuer Derivate des 1,3-Dimethyllumazins. Hartung-Gorre, 1987.

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Heizmann, Gerhard. Methanopterin, ein interessantes Coenzym methanogener Bakterien aus der Sicht der organischen Synthese. Hartung-Gorre, 1991.

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Kang, Yonghan. Synthese und Reaktivität von Acylpteridinen und Vorstufen zum Methanopterin. Hartung-Gorre, 1987.

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Döring, Thomas. Synthese biologisch interessanter 2.7-disubstituierter Acylpteridine. Hartung-Gorre, 1987.

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Milstien, Sheldon, Gregory Kapatos, Robert A. Levine, and Barry Shane, eds. Chemistry and Biology of Pteridines and Folates. Springer US, 2002. http://dx.doi.org/10.1007/978-1-4615-0945-5.

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Ayling, June E., M. Gopal Nair, and Charles M. Baugh, eds. Chemistry and Biology of Pteridines and Folates. Springer US, 1993. http://dx.doi.org/10.1007/978-1-4615-2960-6.

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Chapitres de livres sur le sujet "Pteridine Pteridine"

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Schomburg, Dietmar, and Dörte Stephan. "Pteridine oxidase." In Enzyme Handbook. Springer Berlin Heidelberg, 1994. http://dx.doi.org/10.1007/978-3-642-57942-4_184.

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Hutchison, Dorris J., and Joseph H. Burchenal. "Studies on Pteridine Metabolism." In Ciba Foundation Symposium - Chemistry and Biology of Pteridines. John Wiley & Sons, Ltd., 2008. http://dx.doi.org/10.1002/9780470718919.ch27.

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Carbon, John A., Robert B. Garland, Dale R. Hoff, Charles F. Howell, William R. Sherman, and E. C. Taylor. "Recent Developments in Pteridine Synthesis." In Ciba Foundation Symposium - Chemistry and Biology of Pteridines. John Wiley & Sons, Ltd., 2008. http://dx.doi.org/10.1002/9780470718919.ch8.

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Chang, Chi-Feng, Tom Bray, Kottayil I. Varughese, and John M. Whiteley. "Comparative Properties of Three Pteridine Reductases." In Advances in Experimental Medicine and Biology. Springer US, 1999. http://dx.doi.org/10.1007/978-1-4615-4735-8_50.

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Werner, E. R., G. Werner-Felmayer, D. Fuchs, A. Hausen, G. Reibnegger, and H. Wachter. "Relationships Between Pteridine Synthesis and Tryptophan Degradation." In Advances in Experimental Medicine and Biology. Springer New York, 1991. http://dx.doi.org/10.1007/978-1-4684-5952-4_16.

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Pardasani, R. T., and P. Pardasani. "Magnetic properties of copper(II)-pteridine complex." In Magnetic Properties of Paramagnetic Compounds. Springer Berlin Heidelberg, 2017. http://dx.doi.org/10.1007/978-3-662-53974-3_225.

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Werner, E. R., G. Werner-Felmayer, H. Wachter, and B. Mayer. "Biosynthesis of nitric oxide: Dependence on pteridine metabolism." In Reviews of Physiology, Biochemistry and Pharmacology. Springer Berlin Heidelberg, 1995. http://dx.doi.org/10.1007/bfb0048266.

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Sawada, Yoshitomo, Haruo Shintaku, Gen Isshiki, Yutaka Hase, Tsuneo Tsuruhara, and Toshiaki Oura. "PTERIDINE VALUES IN CEREBROSPINAL FLUID IN SICK CHILDREN." In February 23–March 2, 1985, St. Christoph, Arlberg, Austria, edited by Helmut Wachter, H. Ch Curtius, and W. Pfleiderer. De Gruyter, 1985. http://dx.doi.org/10.1515/9783110860566-056.

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Golderer, G., S. Leitner, C. Wild, P. Gröbner, E. R. Werner, and G. Werner-Felmayer. "Pteridine and Nitric Oxide Biosynthesis in Physarum Polycephalum." In Chemistry and Biology of Pteridines and Folates. Springer US, 2002. http://dx.doi.org/10.1007/978-1-4615-0945-5_37.

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Hyland, K., and L. A. Arnold. "Clinical Utility of Pteridine Measurement in Cerebrospinal Fluid." In Chemistry and Biology of Pteridines and Folates. Springer US, 2002. http://dx.doi.org/10.1007/978-1-4615-0945-5_55.

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Actes de conférences sur le sujet "Pteridine Pteridine"

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Herrmann Fabian, C., N. Sivakumar, and J. Schmidt Thomas. "In silico identification and in vitro evaluation of new flavonoid inhibitors of pteridine reductase I from Leishmania major (LmPTR1)." In GA 2017 – Book of Abstracts. Georg Thieme Verlag KG, 2017. http://dx.doi.org/10.1055/s-0037-1608036.

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Li, Gao-fei, and Guang-dao Hu. "Reflectance Characteristics and Mechanism Analysis of Pteridium Revolutum in Lead-Zinc Mine Area." In 2010 International Conference on Multimedia Technology (ICMT). IEEE, 2010. http://dx.doi.org/10.1109/icmult.2010.5631198.

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Yizhu Peng, Hongyu Tang, Hailong Li, et al. "Effects of Net photosynthetic rate of pteridium aquilium on photosynthetic active radiation increasing progressively." In 2011 International Conference on Remote Sensing, Environment and Transportation Engineering (RSETE). IEEE, 2011. http://dx.doi.org/10.1109/rsete.2011.5964078.

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CHE, GANG. "Experimental Study on Optimized technological parameters of Preservation for freeze-drying of Pteridium Aquilinum." In The Proceedings of the 5th Asia-Pacific Drying Conference. World Scientific Publishing Company, 2007. http://dx.doi.org/10.1142/9789812771957_0114.

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