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Inhibition of glycerol dehydrogenase from Aerobacter aerogenes by dihydroxyacetone, high ionic strength, and monovalent cations

1968; Elsevier BV; Volume: 159; Issue: 2 Linguagem: Inglês

10.1016/0005-2744(68)90070-3

1878-1454

James E. Strickland, O. Neal Miller,

Enzyme Catalysis and Immobilization

1. The NAD+-linked glycerol dehydrogenase (glycerol:NAD+ oxidoreductase, EC 1.1.1.6) from Aerobacter aerogenes was studied with respect to affinity for several substrates and inhibition by several mechanisms. 2. The affinity of the enzyme was somewaht higher for 1,2-propanediol than for glycerol. At pH 9.5 the Km for 1,2-propanediol was 6.1 mM and for glycerol the Km was 13 mM. 3. The reverse reaction: Dihydroxyacetone+NADH+H+→glycerol+NAD+ showed substrate inhibition at dihydroxyacetone concentrations above 0.4 mM. The Km for dihydroxyacetone was 0.13 mM at pH 7.7 4. The enzyme was strongly inhibited by Li+ and to a lesser extent by Na+ at higher concentrations. The Ki for Li+ was approximately 40 mM at pH 9.5. This inhibition seems to be of a coupling type and appears to be noncompetitive with K+, which has been shown to be an activator for the enzyme. 5. The enzyme was inhibited by high ionic strength solutions.