title: Effect of lactate dehydrogenase isoenzymes on the coupled enzymatic assay for alanine aminotransferase activity.
abstract: We show an example of the importance of specifying the form of isoenzyme and source of indicator enzymes to be used in coupled enzymatic assays. When we compared H-4 (pig heart) and M-4 (rabbit muscle) isoenzymes of lactate dehydrogenase for their suitability as indicator enzymes in the assay for alanine aminotransferase activity, we found that about fourfold as much M-4 as H-4 was required in terms of lactate dehydrogenase activity to reflect accurately equivalent amounts of alanine aminotransferase activity. Moreover, the substrate specificities of the two isoenzymes differed quantitatively.
mesh_terms: D000410:Alanine Transaminase / Q000032:analysis*; D000429:Alcohol Oxidoreductases / Q000032:analysis; D000818:Animals; D005977:Glutarates; D006863:Hydrogen-Ion Concentration; D007527:Isoenzymes; D007700:Kinetics; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D008722:Methods; D009132:Muscles / Q000201:enzymology; D009206:Myocardium / Q000201:enzymology; D011817:Rabbits; D013552:Swine; D013997:Time Factors
chemical_list: D005977:Glutarates; D007527:Isoenzymes; D000429:Alcohol Oxidoreductases; D007770:L-Lactate Dehydrogenase; D000410:Alanine Transaminase