title: Rabbit muscle lactate dehydrogenase 5; a regulatory enzyme.
abstract: Lactate dehydrogenase isozyme 5 from rabbit skeletal muscle is activated by citrate, cis-aconitate, isocitrate, alpha-ketoglutarate, succinate, fumarate, malate, aspartate, and glutamate. In the presence of these activators the shape of the pyruvate saturation curve is changed from sigmoid to hyperbolic. Lactate dehydrogenase isozyme 1 from rabbit heart gives a hyperbolic pyruvate saturation curve and is not activated by these compounds. Oxalacetate is a competitive inhibitor of both isozyme 5 and isozyme 1 but at low concentration it activates the former. These results indicate that lactate dehydrogenase isozyme 5 from rabbit skeletal muscle is an allosteric protein and a regulatory enzyme, while lactate dehydrogenase isozyme 1 from rabbit heart is apparently neither.
mesh_terms: D031841:Aconitum / Q000494:pharmacology; D000818:Animals; D001224:Aspartic Acid / Q000494:pharmacology; D002951:Citrates / Q000494:pharmacology; D005971:Glutamates / Q000494:pharmacology; D066298:In Vitro Techniques; D007656:Ketoglutaric Acids / Q000494:pharmacology; D007700:Kinetics; D007770:L-Lactate Dehydrogenase / Q000378:metabolism*; D007773:Lactates / Q000096:biosynthesis*; D008293:Malates / Q000494:pharmacology; D009132:Muscles / Q000201:enzymology*; D009206:Myocardium / Q000201:enzymology; D009243:NAD / Q000378:metabolism*; D010071:Oxaloacetates / Q000494:pharmacology*; D011773:Pyruvates / Q000378:metabolism*; D011817:Rabbits; D013386:Succinates / Q000494:pharmacology
chemical_list: D002951:Citrates; D005971:Glutamates; D007656:Ketoglutaric Acids; D007773:Lactates; D008293:Malates; D010071:Oxaloacetates; D011773:Pyruvates; D013386:Succinates; D009243:NAD; D001224:Aspartic Acid; D007770:L-Lactate Dehydrogenase