Metabolism of 2‐oxoaldehydes in yeasts

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Abstract
NAD-dependent lactaldehyde dehydrogenase, catalyzing an oxidation of lactaldehyde to lactate, was purified approximately 70-fold from cell extracts of Saccharomyces cerevisiae with a 28% yield of activity. The enzyme was homogeneous on polyacrylamide gel electrophoresis. The relative molecular mass of the enzyme was estimated to be 40000 on Sephadex G-150 column chromatography and on sodium sulfate/polyacrylamide gel electrophoresis. The enzyme was most active at pH 6.5, 60°C and specifically oxidized L-lactaldehyde to L-lactate in the presence of NAD. The Km values for L-lactaldehyde and NAD were 10 mM and 2.9 mM, respectively. The purest enzyme was extremely unstable and almost completely inactivated during storage at -20°C, pH 7.5. For the reactivation of the enzyme, halide ions such as Cl−, I− and Br− were required.