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Peptide Isolated (peptide + isolated)
Selected AbstractsThe solution structure of gomesin, an antimicrobial cysteine-rich peptide from the spiderFEBS JOURNAL, Issue 4 2002Nicolas Mandard Gomesin is the first peptide isolated from spider exhibiting antimicrobial activities. This highly cationic peptide is composed of 18 amino-acid residues including four cysteines forming two disulfide linkages. The solution structure of gomesin has been determined using proton two-dimensional NMR (2D-NMR) and restrained molecular dynamics calculations. The global fold of gomesin consists in a well-resolved two-stranded antiparallel ,,sheet connected by a noncanonical ,,turn. A comparison between the structures of gomesin and protegrin-1 from porcine and androctonin from scorpion outlines several common features in the distribution of hydrophobic and hydrophilic residues. The N- and C-termini, the ,,turn and one face of the ,,sheet are hydrophilic, but the hydrophobicity of the other face depends on the peptide. The similarities suggest that the molecules interact with membranes in an analogous manner. The importance of the intramolecular disulfide bridges in the biological activity of gomesin is being investigated. [source] Adrenomedullin regulates expressions of transforming growth factor-,1 and ,1-induced matrix metalloproteinase-2 in hepatic stellate cellsINTERNATIONAL JOURNAL OF EXPERIMENTAL PATHOLOGY, Issue 3 2006Yi Wang Summary Adrenomedullin (AM), a peptide isolated from human pheochromocytoma, can be produced and secreted by various types of cells including hepatic stellate cells (HSCs), and its possible role in HSCs is not clear now. In the present study, the interactive regulation between transforming growth factor (TGF)-,1 and AM and the effect of AM on TGF-,1-induced matrix metalloproteinase (MMP)-2 expression in HSCs were investigated. TGF-,1 and AM inhibited gene transcript level mutually (real-time reverse transcription-polymerase chain reaction). AM suppressed the protein expression level of TGF-,1 (Western blot), but TGF-,1 might have no effect on AM secretion level. MMP-2 protein expression in HSCs was increased in response to TGF-,1, and upregulation of MMP-2 expression stimulated with TGF-,1 was suppressed by AM in dose-dependent manner (Western blot). AM decreased the phosphorylation level of extracellular signal-regulated kinase (ERK) in HSCs treated with TGF-,1, and TGF-,1-induced MMP-2 expression was suppressed by adding Mitogen-activated protein Kinase/ERK (MEK) inhibitor U0126 (Western blot). Our results suggest that AM may intervene the activation of HSCs by inhibiting TGF-,1 production and TGF-,1-induced MMP-2 expression; AM may suppress the upregulation of MMP-2 expression induced by TGF-,1 partially through ERK pathway. [source] Dichlorvos, chlorpyrifos oxon and Aldicarb adducts of butyrylcholinesterase, detected by mass spectrometry in human plasma following deliberate overdoseJOURNAL OF APPLIED TOXICOLOGY, Issue 6 2010Bin Li Abstract The goal of this study was to develop a method to detect pesticide adducts in tryptic digests of butyrylcholinesterase in human plasma from patients poisoned by pesticides. Adducts to butyrylcholinesterase in human serum may serve as biomarkers of pesticide exposure because organophosphorus and carbamate pesticides make a covalent bond with the active site serine of butyrylcholinesterase. Serum samples from five attempted suicides (with dichlorvos, Aldicarb, Baygon and an unknown pesticide) and from one patient who accidentally inhaled dichlorvos were analyzed. Butyrylcholinesterase was purified from 2 ml serum by ion exchange chromatography at pH 4, followed by procainamide affinity chromatography at pH 7. The purified butyrylcholinesterase was denatured, digested with trypsin and the modified peptide isolated by HPLC. The purified peptide was analyzed by multiple reaction monitoring in a QTRAP 4000 mass spectrometer. This method successfully identified the pesticide-adducted butyrylcholinesterase peptide in four patients whose butyrylcholinesterase was inhibited 60,84%, but not in two patients whose inhibition levels were 8 and 22%. It is expected that low inhibition levels will require analysis of larger serum plasma volumes. In conclusion, a mass spectrometry method for identification of exposure to live toxic pesticides has been developed, based on identification of pesticide adducts on the active site serine of human butyrylcholinesterase. Copyright © 2010 John Wiley & Sons, Ltd. [source] Structure,activity relationship of an antibacterial peptide, maculatin 1.1, from the skin glands of the tree frog, Litoria genimaculataJOURNAL OF PEPTIDE SCIENCE, Issue 7 2004Takuro Niidome Abstract Maculatin 1.1 (Mac) is a cationic antibacterial peptide isolated from the dorsal glands of the tree frog, Litoria genimaculata, and has a sequence of GLFGVLAKVAAHVVPAIAEHF-NH2. A short peptide lacking the N -terminal two residues of Mac was reported to have no activity. To investigate the structure,activity relationship in detail, several analogs and related short peptides of Mac were synthesized. CD measurement showed that all the peptides took more or less an ,-helical structure in the presence of anionic lipid vesicles. Analogs which are more basic than Mac had strong antibacterial and hemolytic activities, while short peptides lacking one or two terminal residues exhibited weak or no activity. Outer and inner membrane permeabilization activities of the peptides were also reduced with shortening of the peptide chain. These results indicate that the entire chain length of Mac is necessary for full activity, and the basicity of the peptides greatly affects the activity. Copyright © 2004 European Peptide Society and John Wiley & Sons, Ltd. [source] Structural requirements of nociceptin antagonist Ac-RYYRIK-NH2 for receptor bindingJOURNAL OF PEPTIDE SCIENCE, Issue 10 2002Michiaki Kawano Abstract Ac-RYYRIK-NH2 is a peptide isolated from the peptide library as an antagonist that inhibits the biological activities of nociceptin, a hyperalgesic neuropeptide. In order to clarify the structural requirements of this peptide for binding to the nociceptin receptor ORL1, systematic structure,activity studies were carried out. The result of Ala-scanning indicated that the N -terminal tripeptide RYY(=Arg-Tyr-Tyr) is crucially important for binding to the ORL1 receptor. Residual truncations from the N - or C -terminus revealed the special importance of the N -terminal Arg residue. The removal of protecting groups indicated that the N -terminal acetyl group is essential, but the C -terminal amide group is insignificant. These results indicated the conspicuous importance of acetyl-Arg at position 1 of Ac-RYYRIK-NH2 as a key structure allowing binding to the receptor. To investigate the binding site of this peptide in the ORL1 receptor, we synthesized and assayed a series of analogues of the nociceptin dibasic repeat region, residues 8,13 of RKSARK. None of the derivatives were active. Ac-RYYRIK-NH2 was inactive for the µ opioid receptor to which nociceptin binds with considerable strength. All the results suggested that the mode of binding between Ac-RYYRIK-NH2 and the ORL1 receptor is different to that between the ORL1 receptor and nociceptin, and that it may consist of interaction with the receptor site to which nociceptin(1,7) or -(14,17) binds. Copyright © 2002 European Peptide Society and John Wiley & Sons, Ltd. [source] The role of tryptophan in the antibacterial activity of a 15-residue bovine lactoferricin peptideJOURNAL OF PEPTIDE SCIENCE, Issue 4 2001Bengt Erik Haug Abstract Bovine lactoferricin is a 25-residue antibacterial peptide isolated after gastric cleavage of the iron transporting protein lactoferrin. A 15-residue fragment, FKCRRWQWRMKKLGA of this peptide sustains most of the antibacterial activity. In this truncated sequence, the two Trp residues are found to be essential for antibacterial activity. The anchoring properties of Trp, as have been observed in membrane proteins, are believed to be important for the interaction of Trp containing antibacterial peptides with bacterial cell membranes. We have investigated the molecular properties which make Trp important for the antibacterial activity of the 15-residue peptide by replacing Trp with natural and unnatural aromatic amino acids. This series of peptides was tested for antibacterial activity against Echerichia coli and Staphylococcus aureus. We found that neither the hydrogen bonding ability nor the amphipathicity of the indole system are essential properties for the effect of Trp on the antibacterial activity of the peptides. Replacement of Trp with residues containing aromatic hydrocarbon side chains gave the most active peptides. We propose that aromatic hydrocarbon residues are able to position themselves deeper into the bacterial cell membrane, making the peptide more efficient in disrupting the bacterial cell membrane. From our results the size, shape and aromatic character of Trp seem to be the most important features for the activity of this class of Trp containing antibacterial peptides. Copyright © 2001 European Peptide Society and John Wiley & Sons, Ltd. [source] A new antimicrobial peptide isolated from Oudneya africana seedsMICROBIOLOGY AND IMMUNOLOGY, Issue 12 2009Riadh Hammami ABSTRACT Oudneya africana R. Br. (Brassicaceae), a wild-growing plant in the arid region of Tunisia, is used in ethno-medicinal treatment of microbial infections. Validation of ethno-therapeutic claims pertaining to the plant was sought by investigating its antimicrobial activity. A proteinaceous extract of the seeds, called AS-3000, showed activity against various organisms including L. monocytogenes, E. coli, B. subtilis, E. hirae, P. aeruginosa, S. aureus and C. albicans. Extract AS-3000 exhibited a synergistic effect against L. ivanovii when combined with vancomycin or chloramphenicol. The post-antibiotic inhibitory effect of the ampicillin/AS-3000 combination was 2.3-fold greater than for the antibiotic alone. The mode of action of AS-3000 on Listeria and Escherichia was visible using SEM. These results support the use of O. africana for treating microbial infections. [source] The peptide hormone xenin induces gallbladder contractions in conscious dogsNEUROGASTROENTEROLOGY & MOTILITY, Issue 3 2007Y. Kamiyama Abstract, Xenin is a 25-amino acid peptide isolated from human gastric mucosa. The biological activities of xenin include modulating intestinal motility and affecting exocrine pancreatic secretion and gastric acid secretion. The physiological effect of xenin on the gastrointestinal tract, however, is incomplete. The objective of this study is to investigate the effects of xenin on the gastrointestinal tract motility of conscious dogs. Gastrointestinal tract and gallbladder contractions were monitored by chronically implanted force transducers. Synthetic xenin was injected intravenously during the interdigestive state with or without pretreatment with cholinergic blockers. The effects of xenin following cholecystectomy and truncal vagotomy were also investigated. Xenin induced gallbladder and jejunal contractions, although a dose-dependent response was shown only with gallbladder contractions. These effects were inhibited by pretreatment with cholinergic blockers, but were not enhanced by truncal vagotomy. The jejunal contractions were completely inhibited by cholecystectomy. The only direct effect of xenin in terms of gastrointestinal motility was to induce gallbladder contractions in conscious dogs. The neural pathway mediating xenin's action was cholinergic, but not the vagal. This novel finding indicates a new role of xenin. [source] Effects of the paratemnus elongatus pseudoscorpion venom in the uptake and binding of the L -glutamate and GABA from rat cerebral cortexJOURNAL OF BIOCHEMICAL AND MOLECULAR TOXICOLOGY, Issue 1 2006Wagner Ferreira dos Santos Abstract L -Glu is the most important and widespread excitatory neurotransmitter of the vertebrates. Four types of receptors for L -glu have been described. This neurotransmitter modulates several neuronal processes, and its dysfunction causes chronic and acute diseases. L -Glu action is terminated by five distinct transporters. Antagonists for these receptors and modulators of these transporters have anticonvulsant and neuroprotective potentials, as observed with the acylpoliamines and peptides isolated from spiders, solitary and social wasp venoms. On the other hand, the major inhibitory neurotransmitter in mammalian nervous tissue is the GABA. Drugs that enhance GABA neurotransmission comprise effective approaches to protecting the brain against neuronal injury. Is this study, we demonstrate for the first time the inhibition of the [3H]L -glu binding to its specific sites in synaptosomal membranes from rat cerebral cortex, produced by 0.027 U of Paratemnus elongatus venom (EC50). The venom of P. elongatus changes Km and Vmax into the high affinity uptake of the L -glu and decreases Km and Vmax into the parameters of the GABA uptake from rat synaptosomes. This leads us to speculate on the possible presence of selective and specific compounds in this venom that act in L -glu and GABA dynamics, and therefore, that can serve as tools and new drug models for understanding these neurotransmissions. © 2006 Wiley Periodicals, Inc. J Biochem Mol Toxicol 20:27,34, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/jbt.20113 [source] Identification of three novel peptides isolated from the venom of the neotropical social wasp Polistes major majorJOURNAL OF PEPTIDE SCIENCE, Issue 7 2007Václav, ovský Abstract Three novel peptides designated as PMM1, PMM2, and PMM3 were isolated and characterized from the venom of the social wasp Polistes major major, one of the most common wasps in the Dominican Republic. By Edman degradation, and MALDI-TOF and ESI-QTOF mass spectrometry, the primary sequences of these peptides were established as follows: PMM1, H-Lys-Arg-Arg-Pro-Pro-Gly-Phe-Thr-Pro-Phe-Arg-OH (1357.77 Da); PMM2, H-Ile-Asn-Trp-Lys-Lys-Ile-Ala-Ser-Ile-Gly-Lys-Glu-Val-Leu-Lys-Ala-Leu-NH2 (1909.19 Da); and PMM3, H-Phe-Leu-Ser-Ala-Leu-Leu-Gly-Met-Leu-Lys-Asn-Leu-NH2 (1317.78 Da). The suggested sequences were confirmed by MS analysis of peptide fragments obtained by enzymatic digestion. The peptide PMM1 is a lysyl-arginyl-Thr6 -bradykinine that belongs to the wasp kinins group. The sequence of the PMM2 peptide is unique; it resembles somewhat the tetradecapeptide amides of the mastoparan group; however, the chain is extended by three additional amino acid residues. The sequence of PMM3 dodecapeptide is homologous to the peptides of the wasp chemotactic group. Copyright © 2007 European Peptide Society and John Wiley & Sons, Ltd. [source] Novel angiotensin I-converting enzyme inhibitory peptides isolated from Alcalase hydrolysate of mung bean proteinJOURNAL OF PEPTIDE SCIENCE, Issue 8 2006Guan-Hong Li Abstract Mung bean protein isolates were hydrolyzed for 2 h by Alcalase. The generated hydrolysate showed angiotensin I-converting enzyme (ACE) inhibitory activity with the IC50 value of 0.64 mg protein/ml. Three kinds of novel ACE inhibitory peptides were isolated from the hydrolysate by Sephadex G-15 and reverse-phase high performance liquid chromatography (RP-HPLC). These peptides were identified by amino acid composition analysis and matrix assisted-laser desorption/ionization time-of-flight tandem mass spectrometry (MALDI-TOF MS/MS), as Lys-Asp-Tyr-Arg-Leu, Val-Thr-Pro-Ala-Leu-Arg and Lys-Leu-Pro-Ala-Gly-Thr-Leu-Phe with the IC50 values of 26.5 µM, 82.4 µM and 13.4 µM, respectively. Copyright © 2006 European Peptide Society and John Wiley & Sons, Ltd. [source] Comparative activity and stability under salinity conditions of different antimicrobial peptides isolated from aquatic animalsAQUACULTURE RESEARCH, Issue 16 2009Sara Emelie Löfgren Abstract This study reports the in vitro activity of six antimicrobial peptides (AMPs) produced by aquatic animals (most marine invertebrates): tachyplesin (Tach), magainin (Mag), clavanin (Clav), penaeidin (Pen), mytilin (Myt) and antilipopolysaccharide factor (ALF) against marine vibrios, filamentous fungi and yeast. Their stability under salinity conditions and seawater was also examined. The results showed that Mag, Myt and especially Tach and ALF (minimum inhibitory concentration<1.5 ,M) had a potent activity against all tested vibrio species, whereas Clav and Pen were ineffective (up to 50 ,M). With respect to the antifungal activity, each AMP had a different potency according to the fungal species. In general terms, Tach was the most potent peptide, followed by Mag. Interestingly, Tach, Myt and ALF had a significant effect on the filamentous fungus Fusarium solani that could be pathogenic to marine organisms. All AMPs had a tendency to decrease or lose their activity at high salinity (>225 mM NaCl). Tach and Myt were the most stable peptides, maintaining significant activity under seawater salinity (450 mM). Curiously, all peptides lost their effect under seawater conditions. The results suggest that Tach, ALF and Myt are the most promising candidates for potential therapeutic use in farmed-marine species, because all have a significant and broad antimicrobial activity maintained at high salinity. [source] | |||||||||||||