Occurrence of a novel yeast enzyme, L-lysine epsilon-dehydrogenase, which catalyses the first step of lysine catabolism in Candida albicans.

The yeast Candida albicans is able to utilize L-lysine as the sole nitrogen and carbon source accompanied by intracellular accumulation of alpha-aminoadipate-delta-semialdehyde. A novel yeast amino acid dehydrogenase catalysing the oxidative deamination of the epsilon-group of L-lysine was found in this yeast. The enzyme, L-lysine epsilon-dehydrogenase, is strongly induced in cells grown on L-lysine as the sole nitrogen source. The enzyme is specific for both L-lysine and NADP+. The Km values were determined to be 0.87 mM for L-lysine and 0.071 mM for NADP+. An apparent Mr of 87,000 was estimated by gel filtration. The enzyme has maximum activity at pH 9.5 and a temperature optimum of 32 degrees C under our assay conditions.