title: Kinetic study by pulse radiolysis of the lactate dehydrogenase-catalyzed chain oxidation of nicotinamide adenine dinucleotide by HO2 and O2-RADICALS.
abstract: The lactate dehydrogenase-catalyzed chain oxidation of NADH (LDH-NADH) by the superoxide radicals, HO2 and O2, has been studied with pulse radiolysis in the pH range between 4.5 and 9.0. The rate constants for the oxidation of the LDH-NADH by HO2 and O2 determined at 23 degrees are 1.2 times 10-6 M(-1) s(-1) and 3.6 times 10-4 M(-1) s(-1), respectively. The latter represents an activation of over 1000-fold by the enzyme. A chain reaction mechanism consistent with the results from these kinetic studies has been proposed.
mesh_terms: D000818:Animals; D001665:Binding Sites; D004789:Enzyme Activation; D005609:Free Radicals; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D007770:L-Lactate Dehydrogenase / Q000378:metabolism*; D008433:Mathematics; D009206:Myocardium / Q000201:enzymology; D009243:NAD; D010084:Oxidation-Reduction; D010100:Oxygen; D011485:Protein Binding; D013056:Spectrophotometry, Ultraviolet; D013552:Swine; D013696:Temperature; D013997:Time Factors
chemical_list: D005609:Free Radicals; D009243:NAD; D007770:L-Lactate Dehydrogenase; D010100:Oxygen