Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P01178 (oxytocin)
 15,767 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Systematic analysis of the hydrolysis of benzyloxycarbonyl (Cbz)-dipeptides by cathepsin A [EC 3.4.12.1] purified from rat liver lysosomes showed that multiple forms of cathepsin A preferentially cleave peptide bonds with leucine, methionine, and phenylalanine. Cbz-Met-Met, -Met-Phe, -Phe-Met, and -Phe-Ala were hydrolyzed 6 to 8 times faster than the standard substrates, Cbz-Glu-Phe and Cbz-Glu-Tyr. The pH optima of the hydrolyses were 4.6 to 5.8. Hydrolysis of peptide bonds with glycine, isoleucine, and proline was very slow, but the rate depended on the nature of the adjacent amino acids. Proteins such as albumin, cytochrome c, gamma-globulin, hemoglobin, histone, myoglobin, and myosin were scarecely degraded. Peptide hormones, such as glucagon and adrenocorticotropic hormone (ACTH) were hydrolyzed markedly with optimum pH's of 4.5 and 4.6, respectively. Angiotensin I, II, bradykinin, Lys- and Met-Lysbradykinin (kallidin and Met-kallidin), and substance P were also hydrolyzed at appreciable rates. pH optima for these peptide hormones were 5.2 to 5.6. On the other hand, insulin and its A chain, luteinizing hormone-releasing hormone (LH-RH), oxytocin and vasopressin were cleaved slowly. In the hydrolyses of glucagon and other peptides, multiple forms of rat liver lysosomal cathepsin A again showed a carboxypeptidase nature, cleaving peptide bonds sequentially from the carboxyl terminal. Almost all of the amino acids were cleaved on prolonged incubation. Vaso-activites of angiotensin II and bradykinin were rapidly lost on hydrolysis by cathepsin A. Lysosomal cathepsin C [dipeptidylaminopeptidase I, EC 3.4.14.1] also activated angiotensin II, but did not inactive bradykinin. Cathepsin A, therefore, can be regarded as one of the lysosomal angiotensinases and kinases. No distinct differences were observed between the multiple forms of cathepsin A in these hydrolyses and inactivations of peptides.
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PMID:Studies on cathepsins of rat liver lysosomes. III. Hydrolysis of peptides, and inactivation of angiotensin and bradykinin by cathepsin A. 1 61

Endopeptidase-2, the second endopeptidase in rat kidney brush border [Kenny & Ingram (1987) Biochem. J. 245, 515-524] has been further characterized in regard to its specificity and its contribution to the hydrolysis of peptides by microvillar membrane preparations. The peptide products were identified, after incubating luliberin, substance P, bradykinin and angiotensins I, II and III with the purified enzyme. The bonds hydrolysed were those involving a hydrophobic amino acid residue, but this residue could be located at either the P1 or P1' site. Luliberin was hydrolysed faster than other peptides tested, followed by substance P and bradykinin. Human alpha-atrial natriuretic peptide and the angiotensins were only slowly attacked. Oxytocin and [Arg8]vasopressin were not hydrolysed. No peptide fragments were detected on prolonged incubation with insulin, cytochrome c, ovalbumin and serum albumin. In comparison with pig endopeptidase-24.11 the rates for the susceptible peptides were, with the exception of luliberin, much lower for endopeptidase-2. Indeed, for bradykinin and substance P the ratio kcat./Km was two orders of magnitude lower. Since both endopeptidases are present in rat kidney microvilli, an assessment was made of the relative contributions to the hydrolysis of luliberin, bradykinin and substance P. Only for the first named was endopeptidase-2 the dominant enzyme; for bradykinin it made an equal, and for substance P a minor, contribution.
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PMID:The metabolism of neuropeptides. Hydrolysis of peptides by the phosphoramidon-insensitive rat kidney enzyme 'endopeptidase-2' and by rat microvillar membranes. 246 6

1. Measurements have been made of the interaction of cytochrome c, bovine serum albumin and synthetic oxytocin with low-pressure (2dyn/cm) monolayers of stearic acid, phosphatidylcholine and phosphatidylethanolamine. 2. [(14)C]Carboxymethylation of the cytochrome c and albumin followed by surface-radioactivity determinations have shown that only a proportion of the protein added to the subphase is bound to the monolayers and that initially the degree of binding is dependent on the protein concentration. The binding is irreversible in the sense that the adsorbed protein cannot be removed by transferring the film containing the interacted protein to a fresh subphase containing no protein. 3. Three successive types of interaction can usually be recognized. (a) Initially, whole molecules of protein penetrate the lipid film and occupy the same area as those of the protein spread at the air/water interface. (b) Above certain film pressures a part of each protein molecule, probably hydrophobic side chains, penetrates the film. The change in surface pressure per unit of bound protein is much smaller than in (a). (c) At higher film pressures, adsorption without penetration occurs. With cytochrome c this is initially dependent on a favourable electrostatic interaction.
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PMID:An analysis of the interaction of protein with lipid monolayers at the air-water interface. 546 19

The biosynthesis of [arginine8]vasopressin (AVP) and oxytocin (OT) was studied, and the results obtained have been compared with a study of their associated neurophysins (NP), AVP-NP and OT-NP. Rat hypothalamic extracts obtained at acid pH were subjected to Sephadex G-75 gel filtration chromatography and sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis (PAGE). Fractions of gel chromatography effluent and extract of SDS-PAGE gel slices were subjected to RIA for immunoreactive precursors of AVP, AVP-NP, OT, and OT-NP using specific antisera fro each molecule. Tritiated bovine serum albumin, ovalbumin, and cytochrome c were used as internal standards during gel filtration chromatography and SDS-PAGE. Molecular weight estimates obtained for precursors of AVP were more than 70K, 31K, 13K, 5K, and less than 5K (AVP) by G-75 chromatography and more than 70K, 39K, 15K, and less than 5K (AVP) by SDS-PAGE. Molecular weight estimates obtained for precursors of AVP-NP were more than 70K, 35K, 24K, and 12K (AVP-NP) by G-75 chromatography and 19K and 10K (AVP-NP) by SDS-PAGE. Molecular weight estimates of OT were more than 70K, 35K, 19K, 8K, and less than 5K (OT) by G-75 chromatography and 60K, 35K, 19K, 9K, and less than 5K (OT) by SDS-PAGE. Precursors of OT-NP were estimated to be more than 70K, 17-18K, and 10K (OT-NP) by G-75 chromatography and 28K, 18K and 10K (Ot-NP) by SDS-PAGE. These studies show that there are small differences in precursor processing among AVP, AVP-NP, and OT, OT-NP, but allow for the existence of common precursors for AVP and AVP-NP and for OT and OT-NP.
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PMID:Putative precursors of vasopressin, oxytocin, and neurophysins in the rat hypothalamus. 728 61