Metabolism of 2‐oxoaldehydes in yeasts

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 K m 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.