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The kinetics of the interconversion of intermediates of the reaction of pig muscle lactate dehydrogenase with oxidized nicotinamide-adenine dinucleotide and lactate.

ABSTRACT: Oxamate competes with pyruvate for the substrate binding site on the E(NADH) complex of pig skeletal muscle lactate dehydrogenase. When this enzyme was mixed with saturating concentrations of NAD(+) and lactate in a stopped-flow rapid-reaction spectrophotometer there was no transient accumulation of enzyme complexes with the reduced nucleotide. The steady-state rate of formation of free NADH was reached within the dead-time of the instrument (3ms). When oxamate was added to inhibit the steady state and to uncouple the equilibration: [Formula: see text] through the rapid formation of E(NADH) (Oxamate), the rate of formation of E(NADH) could be measured by observation of the first turnover. This pH-dependent transient is controlled by the rate of dissociation of pyruvate and the fraction of the enzyme in the form E(NADH) (Pyruvate).

SUBMITTER: Bennett NG

PROVIDER: S-EPMC1165791 | biostudies-other | 1973 Sep

REPOSITORIES: biostudies-other

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