title: S-adenosyl-L-homocysteine hydrolase from Dictyostelium discoideum is inactivated by cAMP and reactivated by NAD+.
abstract: Purified S-adenosyl-L-homocysteine hydrolase from Dictyostelium discoideum is inactivated when incubated at 25 degrees C with cAMP. Half maximal velocity of the inactivation process occurs at 10 microM cAMP. Catalytic activity is fully restored by further incubation with NAD+, but not with NADP+ or NADH. The enzyme must be preincubated with cAMP or NAD+ to induce inactivation or reactivation, respectively, since neither of these ligands has an effect on the active or inactive enzyme when added directly to the assay. These results suggest a role for cAMP and NAD+ in the regulation of cellular methylation reactions by altering the level of S-adenosyl-L-homocysteine via S-adenosyl-L-homocysteine hydrolase.
mesh_terms: D043383:Adenosylhomocysteinase; D000242:Cyclic AMP / Q000494:pharmacology*; D004023:Dictyostelium / Q000201:enzymology; D004789:Enzyme Activation / Q000187:drug effects*; D004793:Enzyme Reactivators / Q000494:pharmacology*; D006867:Hydrolases / Q000378:metabolism*; D007700:Kinetics; D009243:NAD / Q000494:pharmacology*
chemical_list: D004793:Enzyme Reactivators; D009243:NAD; D000242:Cyclic AMP; D006867:Hydrolases; D043383:Adenosylhomocysteinase