Mechanistic implications of cyclic ADP-ribose hydrolysis and methanolysis catalyzed by calf spleen NAD+glycohydrolase.

Calf spleen NAD+glycohydrolase, besides its well known reactions, was shown to catalyze hydrolysis and methanolysis (with retention of configuration) of cyclic ADP-ribose, indicating that this classical NADase also belongs to the class of cyclic ADP-ribose hydrolases. No formation of cyclic ADP-ribose could be detected during the hydrolysis of beta-NAD+; moreover, the kinetic parameters of cyclic ADP-ribose seem to rule out that it is a kinetically competent reaction intermediate in the conversion of NAD+ into ADP-ribose by this enzyme.