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)

Arginine-vasopressin and oxytocin, both 14C-labeled in the glycine residue, are enzymatically inactivated by rat kidney supernatant. Production of radioactive metabolites of each hormone was followed as a function of time. Both oxytocin and vasopressin are degraded by an enzyme which cleaves their Pro-X bonds, to release Leu-Gly-NH2 from oxytocin and Arg-Gly-NH2 from vasopressin. In addition, oxytocin alone is degraded rapidly by a chymotrypsin-like enzyme which directly releases Gly-NH2 from the hormone. The direct release of Gly-NH2 from vasopressin in the homogenate is of minor importance, but there occurs a transient formation of an uncharacterized fragment in significant amounts. The data are interpreted to indicate that the difference in the overall mechanism of inactivation of the two hormones by the rat kidney extract is a result of the high level of the enzymic activity which releases Gly-NH2 directly from oxytocin, compared to the low level of activity releasing Gly-NH2 directly from the antidiuretic hormone. This allows, in the case of arginine vasopressin, a greater expression of the activity of enzyme(s) giving rise to uncharacterized fragment(s) and of the Pro-X cleaving enzyme.
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PMID:Differences in the enzymatic inactivation of arginine vasopressin and oxytocin by rat kidney homogenate. 111 88

A post-proline cleaving enzyme and its endogenous inhibitor have been demonstrated to be present in sperm of the ascidian, Halocynthia roretzi. The enzyme was extracted with artificial sea water from frozen and thawed sperm and isolated from accompanying acrosin-like and chymotrypsin-like enzymes by DEAE-cellulose chromatography. It was then separated from the endogenous inhibitor by ammonium sulfate fractionation and DEAE-Sephacel chromatography. Three subsequent chromatographic operations using hydroxylapatite, Sephadex G-150 and Z-Gly-Pro-Leu-Gly-aminohexyl-Sepharose yielded the highly purified enzyme. The molecular weight and isoelectric point of the enzyme were estimated to be 66,000 and 5.5, respectively. The pH optimum of the activity was 7.0. The enzyme was inactivated with diisopropylphosphorofluoridate, phenylmethylsulfonyl fluoride, Z-Gly-Pro-chloromethyl ketone and sulfhydryl-directed reagents; these inhibitor susceptibilities were similar to those reported for the enzymes of mammalian origins. The ascidian enzyme hydrolyzed oxytocin, angiotensin II, luteinizing hormone releasing hormone and neurotensin at the carboxyl side of proline residues. The endogenous inhibitor was heat stable. The molecular weight of its main component was estimated to be about 8,000. The presence of salt at high concentrations weakened the enzyme-inhibitor interaction. Z-Gly-Pro-chloromethyl ketone inhibited fertilization of the ascidian, suggesting possible involvement of the post-proline cleaving enzyme in fertilization.
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PMID:Isolation and characterization of a post-proline cleaving enzyme and its inhibitor from sperm of the ascidian, Halocynthia roretzi. 636 Oct 7

Carboxamidopeptidase, an enzyme which inactivates neurohypophyseal hormones, has been purified 3800-fold in an overall yield of 22% from toad skin, a neurohypophyseal hormone target organ, by (NH4)2SO4 fractionation, DEAE-Sephadex chromatography, and affinity chromatography on immobilized p-aminobenzamidine and concanavalin A-agrose. The purified enzyme is capable of inactivating both [8-arginine]vasopressin (AVP) and oxytocin by hydrolyzing the Arg8-Gly9-NH2 and the Leu8-Gly9-NH2 bonds, respectively, and can hydrolyze the ester substrates, benzoyl-L-arginine ethyl ester (BzArgOEt) and acetyl-L-trypsine ethyl ester, suggesting that the enzyme has both trypsin-like and chymotrypsin-like activities. Carboxamidopeptidase is maximally active at pH 7.5-8.5 for AVP and BzArgOEt and pH 7.0 for oxytocin. Carboxamidopeptidase is inhibited by ovoinhibitor, ovomucoid, Trasylol. lima bean trypsin inhibitor, concanavalin A, antipain, leupeptin, chymostatin, elastatinal, p-nitrophenyl p-guanidinobenzoate, and 4-methylumbelliferyl p-guanidinobenzoate but not by soybean trypsin inhibitor, alpha 1-antitrypsin, hirudin, pepstatin, bestatin, phosphoramidon, or cysteine. The enzyme is also inhibited by the serine protease inhibitor, diisopropyl phosphofluoridate (i-Pr2PF), and by the chloromethyl ketone derivatives of tosyllysine, tosylphenylalanine, and (benzyloxycarbonyl)phenylalanine, as well as by the sulfhydryl group reagent, p-(chloromercuri)benzoate (PCMB). Inhibition by PCMB is reversed by cysteine. The molecular weight determined by gel filtration in the presence of 1 MNaCl is approximately 100 000. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis indicates that the enzyme is composed of two identical subunits of 48 000 daltons. Each subunit consists of a heavy chain (28 000 daltons) and a light chain (19 000 daltons) joined by a disulfide bond(s). Labeling experiments using [3H]-i-Pr2PF showed that the enzyme active site is located in the heavy chain.
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PMID:Carboxamidopeptidase: purification and characterization of a neurohypophyseal hormone inactivating peptidase from toad skin. 676 14