Inhibitor-contaminated NADH: its influence on dehydrogenases and dehydrogenase-coupled reactions.

commercially available reduced NAP preparatioums for LDH assays. 1)ata on the influence of the inhibitor on otimer dehydrogenases are presented, as well as data concerning time inhibitor in coupled enzyme tests with dehydrogenases as indicator enzymes. Freshly prepareci solutions of various commercially available reduced NAT) preparations were foummd to l)e essentially free of inhibitors acting on dehydrogenases. Tt is show-mmthat time dehydrogenases GLT)T1 (14-glutamate :NAT) oxidoreductase, deaminating, EC 1.4.1.2), ‘‘aHBDH’’ (‘‘-hydroxybutyrate (lelmydrogenase’’), LI)H (L-lactate: NA1) oxidoreductase, EC 1.1.1.27), MDH (L-malate:NAD oxidoreductase, EC 1.1.1.37), almd 81)11 (L-iditol :NAD oxidoreductase, EC 1.1 .1.14) are quite different in their sensitivity against the inhibitor. Experiments witlm coupled elmzyme systems using dehydrogenases as ilmdicatorenzymes have showim that time inhibitor does not affect kinetic assays of ALP (Ketose-1--phosphmate aldehyde-lyase, EC 4.1.2.7), CPK (ATP:ereatine pimosPllotrallsferase, EC 2.7.3.2), (lOT (L-aspartate:2-oxoglutarate aminotransferase, EC 2.6.1.1),OPT (L-alanine:2oxoglutarate anmino transferase, EC 2.6.1.2), and PK (ATP:pyruvate phosphotransferase, EC 2.7.1.40),if the kinetic requirements for coupled enzyme systems are met. From The 11W’ Laboratories, 219 E 44 Sf, New York, NY 10017.