title: The mechanism of adduct formation between NAD+ and pyruvate bound to pig heart lactate dehydrogenase.
abstract: 1. The rate of adduct formation between NAD+ and enol-pyruvate at the active site of lactate dehydrogenase is determined by the rate of enolization of pyruvate in solution. 2. The proportion of enol-pyruvate solutions is less than 0.01%. 3. The overall dissociation constant of adduct formation is less than 5 X 10(-8) M for pig heart lactate dehydrogenase at pH 7.0. 4. The unusual kinetics for adduct formation previously observed in the case of rabbit muscle lactate dehydrogenase [Griffin & Criddle (1970) Biochemistry 9, 1195--1205] may be attributed to the concentration of enol-pyruvate in solution being considerably less than the concentration of enzyme.
mesh_terms: D001665:Binding Sites; D055598:Chemical Phenomena; D002621:Chemistry; D007536:Isomerism; D007700:Kinetics; D007770:L-Lactate Dehydrogenase / Q000378:metabolism*; D009243:NAD / Q000378:metabolism*; D011773:Pyruvates / Q000378:metabolism*
chemical_list: D011773:Pyruvates; D009243:NAD; D007770:L-Lactate Dehydrogenase