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 synthetic prostaglandin 16,16-dimethyl E2 (PGE2) given by intravenous infusion at 0.4 mug/kg-h inhibited gastric secretion of H+, K+, Cl-, and pepsin in four fistula dogs stimulated by histamine (H), pentagastrin (P), urecholine (U), and 2-deoxy-D-glucose (2-DG). When given for 90 min during steady infusions of near-maximal doses of H, P, and U, PG-E2 caused 75% inhibition of H+ maximally at 90 min and over 85% inhibition of pepsin secretion maximally at 45 min. Recovery of secretion took 1-2 h after infusion of PGE2 was stopped. Injection of KCl, 1 meq/kg, during inhibition of histamine by PGE2 gave only a 15-min transient reversal in inhibition. When PGE2 was given as background to 45-min step-dose responses, 0.1 mug/kg competitively inhibited histamine stimulation and 0.4 mug/kg-h gave 100% inhibition. Against pentagastrin, 0.1 mug PGE2/kg-h had no effect and 0.4 mug caused uncompetitive inhibition; against urecholine, 0.4 mug PGE2/kg-h caused competitive inhibition of H+ secretion. Pepsin was more markedly inhibited in each case. There were no side effects at either dose of PGE2, which is a potent inhibitor of gastric secretion with all forms of stimuli.
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PMID:Inhibition of gastric secretion in the dog by 16,16-dimethyl prostaglandin E2. 0 75

Pepsin was spin-labelled with N-(1-oxyl-2,2,6,6-tetramethyl-4-piperidyl) bromoacetamide, possibly at the active site, at a beta-catboxyl group of a reactive aspartic acid. The spectrum of the spin-labelled pepsin showed that the spin probe was strongly immobilized (correlation time is greater than or equal to 10(-8) sec). Spin-labelled pepsin was thermally denatured at various temperatures and electron paramagnetic resonance (e.p.r.) spectra were taken at various times. Rates of denaturation estimated from the e.p.r. spectra at various temperatures showed that the enthalpy and entropy of thermal denaturation of spin-labelled pepsin at pH 3.5 were 48.0+/-4.9 kcal/mole and 214.7+/-14.5 e.u. respectively. Addition of conc. NaOH or 1 M acetate buffer at pH 6.0 sharpened e.p.r. spectra of the spin-labelled pepsin, indicating that the spin probe became mobilized by alkaline denaturation. Addition of urea caused unfolding of the protein which increased with the urea concentration, although only slight transition of conformational changes was observed in the e.p.r. spectra.
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PMID:Electron paramagnetic resonance studies on spin-labelling of pepsin: effects of temperature, pH and urea on its conformation. 0 80

In a series of in vitro studies, both the soluble (plasmatic) coagulation system and the cellular (platelet-mediated) aspect of coagulation were shown to be extremely sensitive to relatively minor increases in hydrogen ion concentration. All studies became abnormal at pH 6.8. At pH 6.4, assays of the intrinsic and extrinsic coaglution systems, the polymerization of fibrinogen, and assay of the availability of platelet phospholipid (platelet factor 3) were twice prolonged over control values. Platelet aggregation was reduced by more than 50%. At pH 5.4 in vitro, platelet aggregation and plasma coagulation were both virtually abolished. Furthermore, previously formed platelet aggregates disaggregated at a slightly acid pH. Pepsin further enhanced platelet disaggregation. Because gastric acidity is normally two to four orders of magnitude greater than that which abolishes platelet aggregation and plasma clotting in vitro, and pepsin is present in abundance, we call attention to the probable antihemostatic effect of hydrocloric acid and pepsin in the upper gastrointestinal tract. This in vitro study may provide a rationale for meticulous regulation of intragastric pH in an effort to control upper gastrointestinal hemorrhage.
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PMID:Effect of acid and pepsin on blood coagulation and platelet aggregation. A possible contributor prolonged gastroduodenal mucosal hemorrhage. 2 30

1. Of the three major human pepsins, pepsin 1 has greater proteolytic activity towards ovalbumin than has pepsin 3. Pepsin 5 has low activity towards this substrate. 2. Proteolytic pH-activity curves show only on pH maximum, about pH 1.4 for pepsin 1, pH 1.4--1.5 for pepsin 3 and pH 1.2--1.4 for pepsin 5. The curve for pepsin 3 has a shoulder between pH 2.4 and 3.4. 3. The rate of digestion of ovalbumin by pepsin 1 is approximately three times slower than are those of bovine haemoglobin or human globin. 4. The results suggest that there may be a physiological advantage in having more than one pepsin.
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PMID:Ovalbumin digestion by human pepsins 1, 3 and 5. 3 68

Pure human pepsins 1 and 3 are inactivated by incubation at pH 7.1-7.3 for 30 minutes, losing 90% or more of activity. Pepsin 5 is alkali-stable, retaining 100% of activity. Mixtures of pure pepsins 1 and/or 3 with pepsin 5 were found to have greater alkali-stable activity than predicted. Two published methods for determining the alkali-stable fraction of the peptic activity of gastric juice gave, respectively, in our hands values of 45.4-80.0% and 27.5-43.9% of the total activity. These values seemed too high to be attributable only to pepsin 5 in gastric juice, as agar gel electrophoresis shows pepsin 3 to have the principal activity. Electrophoretograms of alkaline incubated gastric juice revealed that large amounts of pepsin 3 retained activity as well as pepsin 5, and a proteolytic zone "4" appeared between them. Alkali inactivation thus does not allow the estimation of pepsin 5 individually in gastric juice. Pepstatin, at a final concentration of 100 to 170 pmol/ml, may be used to estimate pepsin 5 in gastric juice and gave values of 18.0 to 27.6% of the total peptic activity. Pepsin 5, in gastric juice and in mixtures of pepsins, appears to protect pepsin 3 from alkaline-inactivation, and to a lesser extent from pepstatin inhibition.
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PMID:Pepsin 5 in gastric juice: determination and relationship to the alkali-stable peptic activity. 4 73

Mouse antibodies to soluble bovine skin (type I) collagen react with determinants which are located in the rigid triple-helical portion of the antigen and become destroyed upon unfolding the molecule. Helical antigenic determinants are dependent on the genuine chain assembly, e.g. alpha[1(I)]2alpha2. Artefactual triplehelical structures of the composition [alpha1(I)]3 or [alpha2]3 or a genetically distinct type II collagen from cartilage showed no or only weak cross-reactivity. Pepsin treatment of type I collagen known to remove short, non-helical sequences at both ends of the molecule had virtually no effect on antigenicity and immunogenic activity. A radioimmunoassay failed to detect antibodies in three congenic resistant mouse strains immunized with denatured type I collagen. These strains had been previously classified as high or low responders to native type I collagen. Agglutination titres vs denatured collagen culd already be demonstrated in nonimmune sera. The agglutinating activity was labile against heating at 56 degrees and could not be increased by immunization. Two out of five inbred strains showed a high response against pepsin-dissolved bovine type II collagen with the chain composition [alpha1(II)]3. Lack of correlation in the responder state to both collagen types indicated control by different immune response genes. Antibodies to type II collagen also reacted against triple-helical antigenic determinants and showed neglible cross-reaction with type I collagen.
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PMID:Specificity of the antibody response in inbred mice to bovine type I and type II collagen. 5 15

Metiamide, 25 mg, antagonized the action of histamine on acid and pepsin secretion from both denervated pouches and innervated stomachs in dogs. In the same preparations its action on pepsin following food, pentagastrin or 2 deoxy-d-glucose was nonsignificant. Following pilocarpine or secretin, metiamide augmented pouch pepsin. The action of every acid stimulant was depressed by metiamide including the direct vagal action of deoxy-d-glucose on the innervated stomach. H2 receptors seem, therefore, to be involved in some form in acid stimulated by the vagi, histamine, pentagastrin and pilocarpine. Pepsin stimulation does not seem to be via H2 receptors with the esception of stimulation by histamine itself.
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PMID:Metiamide: an antagonist of histamine-stimulated gastric acid secretion. 5 35

Chemical modification of standard gammaglobulin with enzyme treatment (pepsin) or stabilization (beta-propiolactone) is able to influence elimination, fragmentation and organ distribution of intravenously administered gammaglobulins as shown in 36 dogs after i.v. application of allogenic and xenogenic gammaglobulin preparations. Pepsin-gammaglobulin was eliminated and fragmented most rapidly. Gammaglobulin concentrations of all preparations in the skin showed as slower decrease than comparable blood concentrations. The highest skin concentrations 10 days after i.v. application were found for beta-propiolactone gammaglobulin with 6.2 +/- 1.6 microgram/g compared to a blood level of 7.9 +/- 0.9 microgram/ml.
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PMID:[Concentration of intravenously administered gammaglobulin preparations in dog skin (author's transl)]. 7 82

Bovine colostral IgG1 was subjected to both papain and pepsin hydrolysis. Papain digestion appeared to be optimal at pH 7.4 in the presence of 0.01 M cysteine. The molecule was split at the COOH-terminal side of the interchain disulfide bond(s), and in addition to Fab fragments, two Fc fragments, designated Fc(I) and Fc(II), were obtained. Both Fc fragments had an identical NH2-terminal sequence, but differed in m.w. by about 10,000, with Fc(II) being the smaller one. Differences were also observed in their circular dichroism (CD) spectra and in their susceptibility to carboxypeptidase hydrolysis. These results suggested that the distinguishing characteristics of the two Fc fragments resided in the COOH-terminal parts of the molecules. Pepsin hydrolysis yielded the expected F(ab')2 and pFc' fragments. This hydrolysis was found to be dependent upon substrate concentration leading to aggregate formation at IgG1 concentrations below 3%.
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PMID:Characterization of the proteolytic fragments of bovine colostral IgG1. 7 49

Gastric acid and pepsin output in response to 2.5 and 25.6 micrograms . kg-1h-1 of histamine dihydrochloride and 0.10 and 6.0 micrograms . kg-1h-1 of pentagastrin was studied before and after cessation of 4 weeks of cimetidine treatment, 1 g/day, in 10 healthy volunteers. Acid output in response to the low dose of histamine increased significantly from an average of 6.7 mmol +/- 1.3 mmol (S.E.M.) before to 10.1 mmol +/- 0.9 mmol after treatment (p = 0.02), whereas acid output in response to the maximal dose of histamine was not significantly different. Parietal cell sensitivity to histamine stimulation increased significantly after the treatment period from a mean of 28.2% +/- 3.2% before treatment to 49.3% +/- 2.8% afterwards (p less than 0.01). The results indicate augmented parietal cell sensitivity in response to histamine stimulation after withdrawal of cimetidine. Both acid output in response to the two doses of pentagastrin and parietal cell sensitivity to pentagastrin stimulation were not significantly different after cessation of cimetidine treatment. Pepsin output and chief cell sensitivity to histamine and pentagastrin stimulation were not significantly influenced by cimetidine treatment.
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PMID:Parietal and chief cell sensitivity to histamine and pentagastrin stimulation before and after cimetidine treatment in healthy subjects. 11 7


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