Differences between magnesium-activated and manganese-activated pyruvate kinase from the muscle of Concholepas concholepas.
In contrast to the Mg2+-activated enzyme, in the presence of Mn2+ pyruvate kinase exhibits hyperbolic kinetics with respect to the substrate phosphoenolpyruvate and is insensitive to fructose 1,6-biphosphate, phenylalanine and alanine. However, with both metal activated species inhibition by excess ADP is observed. In contrast with Mg2+, which affords significant protection against inactivation caused by 5,5'-dithiobis (2-nitrobenzoic acid), the rate of inactivation by this reagent is increased in the presence of Mn2+. Differences in conformational changes induced by combination of pyruvate kinase with Mg2+ or Mn2+ were indicated by u.v. difference spectra.
D000244:Adenosine Diphosphate / Q000378:metabolism; D000409:Alanine / Q000494:pharmacology; D000818:Animals; D004789:Enzyme Activation / Q000187:drug effects; D007700:Kinetics; D008274:Magnesium / Q000494:pharmacology; D008345:Manganese / Q000494:pharmacology; D008974:Mollusca / Q000201:enzymology*; D009132:Muscles / Q000201:enzymology; D010649:Phenylalanine / Q000494:pharmacology; D010728:Phosphoenolpyruvate / Q000378:metabolism; D011770:Pyruvate Kinase / Q000037:antagonists & inhibitors / Q000378:metabolism*; D013057:Spectrum Analysis
D008345:Manganese; D010649:Phenylalanine; D000244:Adenosine Diphosphate; D010728:Phosphoenolpyruvate; D011770:Pyruvate Kinase; D008274:Magnesium; D000409:Alanine