title: The assay of pyruvate kinase activity in gastric mucosa.
abstract: Pyruvate kinase activity in gastric mucosal supernatant preparations shows large responses to exogenous effectors. At pH 7.5, fructose 1,6-diphosphate can cause large stimulations in activity. Alanine inhibits the reaction but this effect is partially reversed by fructose 1,6-diphosphate. In the absence of these compounds, 4.0-5.0 mM phosphoenolpyruvate (PEP) is required to generate maximal activity in the assay system used. Electrophoresis reveals an isoenzyme pattern containing only one form of pyruvate kinase, an M isoenzyme, in both fundic and antral mucosa. The pyruvate kinase of gastric mucosa thus resembles the M-type enzymes of leucocytes and liver. Measurements of activity at both 1.0 mM PEP and 4.0--5.0 mM PEP, with and without additions of fructose 1,6-diphosphate, are recommended for the reliable estimation of pyruvate kinase activity in this tissue.
mesh_terms: D000818:Animals; D003080:Cold Temperature; D004355:Drug Stability; D004381:Duodenal Ulcer / Q000201:enzymology; D004588:Electrophoresis, Cellulose Acetate; D005636:Fructosephosphates / Q000494:pharmacology; D005753:Gastric Mucosa / Q000201:enzymology*; D006598:Hexosediphosphates / Q000494:pharmacology; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007527:Isoenzymes / Q000378:metabolism; D007700:Kinetics; D007962:Leukocytes / Q000201:enzymology; D008099:Liver / Q000201:enzymology; D009132:Muscles / Q000201:enzymology; D009928:Organ Specificity; D010728:Phosphoenolpyruvate / Q000494:pharmacology; D011770:Pyruvate Kinase / Q000378:metabolism*; D051381:Rats; D013045:Species Specificity; D013276:Stomach Ulcer / Q000201:enzymology; D013997:Time Factors
chemical_list: D005636:Fructosephosphates; D006598:Hexosediphosphates; D007527:Isoenzymes; D010728:Phosphoenolpyruvate; D011770:Pyruvate Kinase