1,720,976 research outputs found
Contryphan-Vn: A novel peptide from the venom of the Mediterranean snail Conus ventricosus RID A-4573-2009
No full textThe isolation, purification, and biochemical characterization of the novel peptide Contryphan-Vn, extracted from the venom of the Mediterranean marine snail Conus ventricosus, is reported. Contryphan-Vn is the first Conus peptide described from a vermivorous species and the first purified from the venom of the single Mediterranean Conus species. The amino acid sequence of Contryphan-Vn is Gly-Asp-Cys-Pro-D-Trp-Lys-Pro-Trp-Cys-NH2. As with other contryphans, Contryphan-Vn contains a D-tryptophan residue, is amidated at the C-terminus, and maintains the five-residue intercystine loop size. However, Contryphan-Vn differs from the known contryphans by the insertion of the Asp residue at position 2, by the lack of hydroxylation of Pro(4), and, remarkably, by the presence of the basic residue Lys(6) within the intercystine loop. Although the biological function(s) of contryphans is still unknown, these characteristics suggest distinct molecular target(s) and/or function(s) for Contryphan-Vn. (C) 2001 Academic Press
THE CU,ZN SUPEROXIDE-DISMUTASE ISOENZYMES OF XENOPUS-LAEVIS - PURIFICATION, IDENTIFICATION OF A HETERODIMER AND DIFFERENTIAL HEAT SENSITIVITY RID A-4573-2009
No full textAmino acid sequence of chicken Cu, Zn-containing superoxide dismutase and identification of glutathionyl adducts at exposed cysteine residues RID A-4573-2009
No full textThe copper,zinc-containing superoxide dismutase electromorphs from chicken erythrocytes have been isolated, their complete amino acid sequence determined and the identity of the protein moieties established. All electromorphs are constituted by a polypeptide chain made of 153 amino acid residues, corresponding to a molecular mass of 15598 Da. Accurate molecular mass determination by electrospray mass spectrometry of the separated electromorphs unequivocally proved that, in the chicken superoxide dismutase, either one or two cysteine residues/subunit are involved in a mixed disulfide with glutathione. The same post-translational modification has been proven to occur in human superoxide dismutase. A different rate of S-thiolation by endogenous glutathione was also demonstrated to be responsible for charge heterogeneity in cells. Effect of this modification on the catalytic and molecular properties of superoxide dismutases, and possible mechanisms for the S-thiolation process, were also investigated and discussed
Solution structure of the cyclic peptide contryphan-Vn, a Ca2+-dependent K+ channel modulator RID A-4573-2009
No full textThe solution structure of contryphan-Vn, a cyclic peptide with a double cysteine S-S bridge and containing a D-tryptophan extracted from the venom of the cone snail Conus ventricosus, has been determined by NMR spectroscopy using a variety of homonuclear and heteronuclear NMR methods and restrained molecular dynamics simulations. The main conformational features of backbone contryphan-Vn are a type IV beta-turn from Gly 1 to Lys 6 and a type I beta-turn from Lys 6 to Cys 9. As already found in other contryphans, one of the two prolines-the Pro4-is mainly in the cis conformation while Pro7 is trans. A small hydrophobic region probably partly shielded from solvent constituted front the close proximity of side chains of Pro7 and Trp8 was observed together with a persistent salt bridge between Asp2 and Lys6, which has been revealed by the diagnostic observation of specific nuclear Overhauser effects. The salt bridge was used as a restraint in the molecular dynamics in vacuum but without inserting explicit electrostatic contribution in the calculations. The backbone of the unique conformational family found of contryphan-Vn superimposes well with those of contryphan-Sm and contryphan-R. This result indicates that the contryphan structural motif represents a robust and conserved molecular scaffold whose main structural determinants are the size of the intercysteine loop and the presence and location in the sequence of the D-Trp and the two Pro residues. (C) 2004 Wiley Periodicals, Inc
Human salivary peptides derived from histatins
No full textHuman saliva from a healthy donor was subjected to fractionation by gel chromatography and six pools were collected and analysed by MALDI-TOF-MS and HPLC-ESI-MS. Three peptides, corresponding to 888.3, 687.3, and 524.1 amu and SNYLYDN, YLYDN, and LYDN sequences (determined by automated Edman sequencing), were isolated from pool 4. YLYDN was not previously described in human saliva. The peptides show the common C-terminal sequence of histatin 3 and histatin 1. To exclude the possibility that the three peptides were an artifact of the purification procedure, nine samples of human saliva were collected from healthy donors, immediately acidified with 0.2% TFA, and analysed by RP-HPLC-ESI-MS. The three peptides were detected in all the analyzed samples. SNYLYDN was always found at a concentration higher than that of YLYDN and LYDN. A correlation analysis performed on quantitative data indicated that the three peptides derive only from histatin 3. Other already known histatins also were searched for in the chromatogram. Histatins 1, 2, 3, 5, 6, 7, 8, and 10 were observed, although not in all samples analyzed, whereas other minor histatins were not detected
PRIMARY STRUCTURE FROM AMINO-ACID AND CDNA SEQUENCES OF 2 CU,ZN SUPEROXIDE-DISMUTASE VARIANTS FROM XENOPUS-LAEVIS
No full textCharacterization of a lysine-specific histone demethylase from Arabidopsis thaliana RID A-4573-2009
No full textArabidopsis thaliana has four genes with close homology to human histone H3 lysine 4 demethylase (HsLSD1), a component of various transcriptional corepressor complexes that often also contain histone deacetylases and the corepressor protein CoREST. All four Arabidopsis proteins contain a flavin amine oxidase domain and a SWIRM domain, the latter being present in a number of proteins involved in chromatin regulation. Here, we describe the heterologous expression and biochemical characterization of one of these Arabidopsis proteins (AtLSD1) and show that, similarly to HsLSD1, it has demethylase activity toward mono- and dimethylated Lys4 but not dimethylated Lys9 and Lys27 of histone 3. Modeling of the AtLSD1 three-dimensional structure using the HsLSD1 crystal structure as a template revealed a high degree of conservation of the residues building up the active site and some important differences. Among these differences, the most prominent is the lack of the HsLSD1 Tower domain, which has been shown to interact with CoREST and to be indispensable for HsLSD1 demethylase activity. This observation, together with AtLSD1 peculiar surface electrostatic potential distribution, suggests that the molecular partners of AtLSD1 are probably different from those of the human orthologue
Conus ventricosus venom peptides profiling by HPLC-MS: A new insight in the intraspecific variation RID F-2229-2010 RID A-4573-2009
No full textConus is a genus of predatory marine gastropods that poison the prey with a complex mixture of compounds active on muscle and nerve cells. An individual cone snail's venom contains a mixture of pharmacological agents, mostly short, structurally constrained peptides. This study is focused on the composition of the venom employed by Corms ventricosus Gmelin, 1791, a worm-hunting cone snail living in the Mediterranean Sea. For this purpose, LC coupled to MS techniques has been successfully used to establish qualitative and quantitative differences in conopeptides from minute amounts of venom ducts. We were able to prove variability in the venom conopeptide complement, possibly related to different trophic habits of the species in the Mediterranean Sea. Moreover, the information-rich MS techniques enabled us to identify two novel C. ventricosus peptides, here named Conotoxin-Vn and alpha-Conotoxin-Vn. On the basis of the structural data collected so far, we suggest that Conotoxin-Vn is a conopeptide belonging to the omega-family that recognizes calcium channels through a specific pharmacophore. Similarly, molecular modeling data suggest that alpha-Conotoxin-Vn should represent a competitive antagonist of neuronal nicotinic acetylcholine receptors (nAChRs)
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