Lysine degradation in Candida. Characterization and probable role of L-norleucine-leucine, 4-aminobutyrate and delta-aminovalerate:2-oxoglutarate aminotransferases.

Three enzymes partially purified that catalyze respectively the transamination of L-norleucine, 4-aminobutyrate and delta-aminovalerate with alpha-ketoglutarate as aminoacceptor were characterized and isolated from L-lysine adapted cell of Candida guilliermondii var. membranaefaciens. The transaminases have a maximum activity in the pH range of 7.8-8.5 and at 55 degrees C, 45 degrees C and 40 degrees C respectively. alpha-Ketoglutarate and to a lesser extent pyridoxal-5'-phosphate were effective protecting agents against rise in temperature. The enzymes exhibit absorption maximum at 280 nm, 330 nm and 410 nm. The fact that L-norleucine-leucine aminotransferase, 4-aminobutyrate aminotransferase and delta-aminovalerate aminotransferase are strongly induced by growing the yeast Candida on L-lysine suggests new hypothetic pathways for the catabolism of L-lysine where the main substrate of each aminotransferase could be an intermediary metabolite.