Regulation of Alanine Dehydrogenase in Bacillus licheniformis

This is the authors' abstract. We don't add key points for this paper.

Cell extracts of Bacillus licheniformis were found to contain nicotinamide adenine dinucleotide (NAD)-dependent l -alanine dehydrogenase (ADH) ( l -alanine: NAD oxidoreductase, EC 1.4.1.1). High specific activities (3.5 to 6.0 IU/mg of protein) were found in extracts of cells throughout growth cycles only when l -alanine served as the primary source of carbon or carbon and nitrogen. Specific activities were minimal (0.02 to 0.04 IU/mg of protein) during growth on glucose, but increased at least sevenfold during the first 5 h of postlogarithmic-phase metabolism. Addition of 10 mM glucose to cultures during logarithmic-phase growth on l -alanine resulted in a rapid decrease in enzyme activity. Addition of 20 mM l -alanine to cells near the completion of log-phase growth on glucose resulted in a 20-fold increase in ADH specific activity during less than one cell generation. Extracts of postlogarithmic-phase cells cultured on glucose, malate, l -glutamate, or Casamino Acids contained intermediate levels of ADH activity. The enzyme was partially purified from crude extracts of B. licheniformis , and apparent kinetic constants were estimated. A role for ADH in the catabolism of l -alanine to pyruvate during vegetative growth on l -alanine and during sporulation of cells cultured on glucose is proposed on the basis of these experimental results.