Effect of NADP(+) and its analogs on the Rose Bengal-sensitized photoinactivation of D-erythrulose reductase from beef liver

• Published in: Journal of biochemistry (Tokyo) 1979-01, Vol.85 (4), p.1003-1008
• Main Authors: UEHARA, Kihachiro, MANNEN, Shigeyasu, HOSOMI, Saburo
• Format: Article
• Language: English
• Subjects: Adenosine Monophosphate; Animals; Cattle; Circular Dichroism; Kinetics; Light; Liver - enzymology; NADP - analogs & derivatives; NADP - pharmacology; Oxidation-Reduction; Protein Conformation; Rose Bengal - pharmacology; Structure-Activity Relationship; Sugar Alcohol Dehydrogenases - antagonists & inhibitors; Tetroses
• ISSN: 0021-924X; 1756-2651
• DOI: 10.1093/oxfordjournals.jbchem.a132406

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 K1's (6–13 µM). Photooxidation of some methionine residues in the enzyme is prevented by the addition of NADP+ and accelerated in the presence of 2′-AMP. Photooxidation product(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 n-erythrulose reductase.