Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P00790 (PGA)
 2,475 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effect of omeprazole, an inhibitor of the parietal cell H+-K+-ATPase, on pepsin and acid secretion was studied in an in vitro perfused whole mouse stomach model. Omeprazole inhibited basal and dibutyryl cAMP (DBcAMP)- and histamine-stimulated acid secretion in a dose-dependent fashion with a maximally effective dose of 10(-4) M. At the same time, omeprazole induced a dose-dependent increase of unstimulated pepsin release. This increase was not affected by pretreatment with 10(-3) M atropine or 10(-4) M cimetidine. It was, however, inhibited by preincubation with 10(-4) M carbonyl cyanide m-chlorophenylhydrazone (CCCP). Pepsin secretion after maximally effective doses of histamine or DBcAMP was not affected by 10(-4) M omeprazole. In a concentration of 10(-5) M, the effect of omeprazole was additive to the effect of submaximal concentrations of carbachol and histamine. NaSCN and imidazole mimicked the effect of omeprazole on acid secretion, but pepsin release was only stimulated with 10(-2) M imidazole. Another weak base, benzylamine, stimulated acid and pepsin in parallel. Luminal perfusion with solutions of high K+ concentration did not enhance basal pepsin release. The dissociated response of acid and pepsin secretion indicates that omeprazole does not act selectively on the parietal cell. The stimulation of pepsin secretion might be related to the weak base properties of the compound.
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PMID:Dissociated response of acid and pepsin secretion to omeprazole in an in vitro perfused mouse stomach. 608 88

The rates of proteolytic breakdown for native human hemoglobin (Hb) in CNmet-and oxy-forms, for isolated native alpha- and beta-chains of human Hb with deprotected SH-groups and for apo-Hb--globin at constant temperature 20 degrees as well as for metHb and globin in the temperature range 4-25 degrees were studied. The proteolysis of oxy-forms of proteins was performed in the presence of CN- to prevent the appearance in solution of quickly splitted aqua and hydroxy met-forms. Pepsin (at pH 5.5), trypsin (at pH 7.0 and 8.5) and protease VI (pronase) (at pH 7.0 and 8.5) were used as proteases. The rate of proteolysis was registered simultaneously by proteolysate precipitation in concentrated salt solutions (to determine the content of the native form), by precipitation in aqueous solution of trichloroacetic or perchloric acid and by colouring the terminal NH2-groups by ninhidrin in the total proteolysate. For most cases the data of all the three independent methods fell on a single kinetic curve, each pair protein--protease being represented by their individual curves. Therefore the breakdown of all the protein studied possesses a burst-like ("one-by-one", "all-or-none") character. The protein resistance to the attack by proteolytic enzymes increases in the following order: globin less than oxy-alpha-chain less than metHb less than oxy-beta-chain less than HbO2 congruent to CNmetHb. The use of control repeated proteolysis has made it possible to prove that differences in the rate of proteolytic degradation are not the consequence of spontaneous denaturation of the least unstable forms of proteins in the course of proteolytic reaction but are predetermined by the conformational state of the native macromolecule.
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PMID:[Proteolytic degradation of native hemoglobin and its constituent parts--isolated subunits and globin. I. Kinetic data and the character of the process of the breakdown of native forms]. 681 53