Re-evaluation of the kinetics of lactate dehydrogenase-catalyzed chain oxidation of nicotinamide adenine dinucleotide by superoxide radicals in the presence of ethylenediaminetetraacetate

Journal Article · Thu Jan 01 00:00:00 EST 1976 · J. Biol. Chem.; (United States)

OSTI ID:7332167

Bielski, B H.J.; Chan, P C

The chain oxidation of lactate dehydrogenase-bound NADH initiated by superoxide radicals and propagated by oxygen was studied with pulse radiolysis. The kinetic parameters were re-evaluated in a system with carefully purified reagents (water and other chemicals) and in the presence of EDTA. The rate constant for the oxidation of the enzyme-bound NADH by O/sub 2//sup -/ is calculated from the observed pseudo-first order disappearance of NADH and the chain length (molecules of NADH oxidized per O/sub 2//sup -/ anion generated in the pulse). It is (1.0 +- 0.2) x 10/sup 5/ M/sup -1/ S/sup -1/, consistent within a 13-fold variation in lactate dehydrogenase.NADH complex concentration and with varying chain length up to 6.1. Based on experiments with varying pH values from 4.5 to 9.0, the rate constant for oxidation of enzyme-bound NADH by HO/sub 2/ is estimated to be 2.0 x 10/sup 6/ M/sup -1/ S/sup -1/.

• Research Organization: Brookhaven National Lab., Upton, NY
• OSTI ID: 7332167
• Journal Information: J. Biol. Chem.; (United States), Vol. 251:13
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
NADH2
OXIDATION
BIOCHEMICAL REACTION KINETICS
EDTA
LACTATE DEHYDROGENASE
OXYGEN
RADICALS
RADIOLYSIS
AMINO ACIDS
CARBOXYLIC ACIDS
CHELATING AGENTS
CHEMICAL RADIATION EFFECTS
CHEMICAL REACTIONS
CHEMISTRY
COENZYMES
CRYOGENIC FLUIDS
DECOMPOSITION
DEHYDROGENASES
ELEMENTS
ENZYMES
FLUIDS
KINETICS
NONMETALS
NUCLEOTIDES
ORGANIC ACIDS
ORGANIC COMPOUNDS
OXIDOREDUCTASES
RADIATION CHEMISTRY
RADIATION EFFECTS
REACTION KINETICS
550200* - Biochemistry