title: The resolution of some steps of the reactions of lactate dehydrogenase with its substrates.
abstract: 1. The reaction of pig heart lactate dehydrogenase (EC 1.1.1.27) with NAD(+) and lactate to form pyruvate and NADH was followed by rapid spectrophotometric methods. The distinct spectrum of enzyme-bound NADH permits the measurement of the rate of dissociation of this compound. 2. The reduction of the first mole equivalent of NAD(+) per mole of enzyme sites can also be observed, and is much more rapid than the steady-state rate of NADH production. 3. At pH8 the dissociation of the enzyme-NADH complex is rate-determining for the steady-state oxidation of lactate. At lower pH some other step after the interconversion of the ternary complex and before the dissociation of NADH is rate-determining. Other evidence for a compulsory-order mechanism is provided.
mesh_terms: D000818:Animals; D001665:Binding Sites; D055598:Chemical Phenomena; D002621:Chemistry; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D007770:L-Lactate Dehydrogenase; D009206:Myocardium / Q000201:enzymology*; D009243:NAD; D013053:Spectrophotometry; D013552:Swine
chemical_list: D009243:NAD; D007770:L-Lactate Dehydrogenase