INHIBITION OF NUCLEOSIDE DIPHOSPHATE KINASE (NDPK NM23) BY CAMP ANALOGS/

Nucleoside diphosphate kinase (NDPK/nm23) ATP/GDP phosphotransferase a ctivity and serine autophosphorylation is inhibited by N-6-mbcAMP, 8-C lcAMP and 8-BrcAMP. Inhibition of the enzymatic activity largely depen ds on the concentration of ATP and becomes significant at ATP concentr ations up to 0.5 mM and at effector concentrations measured in C6 cell s stimulated with 1 mM cAMP analogue. N-6-mbcAMP is a substrate of the enzyme. DbcAMP and O'2- mbcAMP, cAMP analogues with a modified O'2-ri bose, did not affect the NDPK activity. Cyclic AMP is only a moderate inhibitor of NDPK even at low ATP concentrations. Possible inhibitory effects of cAMP and cAMP analogues on reported extra- and intracellula r functions of NDPK/nm23 are discussed.