title: Effect of NADP+ and its analogs on the Rose Bengal-sensitized photoinactivation of D-erythrulose reductase from beef liver.
abstract: Upon addition of NADP+, the rose bengal-sensitized photoinactivation of D-erythrulose reductase from beef liver is prevented to a remarkable extent. Adenosine 2',5'-diphosphate (2',5'-ADP) also has a protective effect, but to a lesser extent. On the other hand, 2'-AMP markedly enhances the photoinactivation. Other nucleotides which have no 2'-phosphoryl group, such as NAD+, 3'-AMP, 5'-AMP, ADP, and NMN, are ineffective. Further, only 2'-AMP derivatives (NADP+, 2',5'-ADP, and 2'-AMP) among these nucleotides were found to be potent competitive inhibitors of the enzyme with small Ki's (6--13 muM). Photooxidation of some methionine residues in the enzyme is prevented by the addition of NADP+ and accelerated in the presence of 2'-AMP. Photooxidation products(s) of 2'-AMP derivatives have no effect upon the enzymatic activity. Although NADP+ and 2'-AMP induce detectable conformational changes of the enzyme, the changes are not characteristic to the compounds. Based on these observations, we present a possible action mechanism of 2'-AMP derivatives on the photoinactivation of D-erythrulose reductase.
mesh_terms: D000249:Adenosine Monophosphate; D000818:Animals; D002417:Cattle; D002942:Circular Dichroism; D007700:Kinetics; D008027:Light; D008099:Liver / Q000201:enzymology*; D009249:NADP / Q000031:analogs & derivatives* / Q000494:pharmacology*; D010084:Oxidation-Reduction; D011487:Protein Conformation; D012395:Rose Bengal / Q000494:pharmacology*; D013329:Structure-Activity Relationship; D013401:Sugar Alcohol Dehydrogenases / Q000037:antagonists & inhibitors*; D013780:Tetroses
chemical_list: D013780:Tetroses; D012395:Rose Bengal; D000249:Adenosine Monophosphate; D009249:NADP; D013401:Sugar Alcohol Dehydrogenases