Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P01185 (vasopressin)
 23,126 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The role of reactive SH groups (presumably in proteins) of the apical plasma membrane in transepithelial Na+ transport was studied in the isolated urinary bladder of the toad. On the basis of assays for TCA-soluble SH compounds (e.g., glutathione, methionine), PCMB, PCMPS, NTCB, and DTNB did not penetrate the intracellular compartment from the luminal media either in control or vasopressin-treated bladders. In contrast, PCMB from the serosal side and NEM from the luminal side titrated significant fractions of the TCA-soluble SH compounds. We conclude, therefore, the PCMB, PCMPS, NTCB, and DTNB are suitable reagents for studies on the physiological properties of apical plasma membrane SH groups. Titration of apical membrane SH groups with PCMPS, NTCB, and DTNB revealed heterogeneity in functional responses: PCMPS and NTCB elicited transient, 25-60% increases in SCC. In substrate-free media, pretreatment with these reagents inhibited the increase in SCC produced by vasopressin or cyclic AMP (+ theophylline). In glucose-enriched media, the responses to combinations of vasopressin and PCMPS or NTCB were additive, implying activation via parallel pathways. Simultaneous addition of vasopressin or cyclic AMP (+ theophylline) and NTCB resulted in marked synergism, presumably as a result of unmasking of SH groups by the the hormone (or the intermediate). These results suggest that basal Na+ transport is regulated in part by SH compounds in the apical membrane that are distinct, although not necessarily different in kind, from those involved in the response to vasopressin.
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PMID:Effects of sulfhydryl reagents on basal and vasopressin-stimulated Na+ transport in the toad bladder. 16 61

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