Degradation of NAD(H) by endogenous enzymes of yeasts and Clostridia.

The time courses of degradation of exogenous NAD and NADH (2.5 mM) catalyzed by endogenous enzymes present in Saccharomyces cerevisiae, Candida utilis, Clostridium spec. La 1, Clostridium kluyveri, and Clostridium sporogenes have been determined. The half lives of the pyridine nucleotides depend extremely on the organism and, for the same organism, on the growth conditions. C. spec. La 1 as well as C. kluyveri possess only negligible enzyme activities for NAD degradation. However, C. sporogenes shows activities leading to half lives of less than 2 h for NAD and 5 h for NADH. At 25 degrees C half lives in the order of 5-17 h have been observed for Candida utilis under different conditions. The half lives of NAD are roughly 5 times higher in the presence of Saccharomyces cerevisiae.