title: Inhibition of NAD glycohydrolase and ADP-ribosyl transferases by carbocyclic analogues of oxidized nicotinamide adenine dinucleotide.
abstract: Analogues of oxidized nicotinamide adenine dinucleotide (NAD+) in which a 2,3-dihydroxycyclopentane ring replaces the beta-D-ribonucleotide ring of the nicotinamide riboside moiety of NAD+ have recently been synthesized [Slama, J. T., & Simmons, A. M. (1988) Biochemistry 27, 183]. Carbocyclic NAD+ analogues have been shown to inhibit NAD glycohydrolases and ADP-ribosyl transferases such as cholera toxin A subunit. In this study, the diastereomeric mixture of dinucleotides was separated, and the inhibitory capacity of each of the purified diastereomers was defined. The NAD+ analogue in which the D-dihydroxycyclopentane is substituted for the D-ribose is designated carba-NAD and was demonstrated to be a poor inhibitor of the Bungarus fasciatus venom NAD glycohydrolase. The diastereomeric dinucleotide pseudo-carbocyclic-NAD (psi-carba-NAD), containing L-dihydroxycyclopentane in place of the D-ribose of NAD+, was shown, however, to be a potent competitive inhibitor of the venom NAD glycohydrolase with an inhibitor dissociation constant (Ki) of 35 microM. This was surprising since psi-carba-NAD contains the carbocyclic analogue of the unnatural L-ribotide and was therefore expected to be a biologically inactive diastereomer. psi-Carba-NAD also competitively inhibited the insoluble brain NAD glycohydrolase from cow (Ki = 6.7 microM) and sheep (Ki = 31 microM) enzyme against which carba-NAD is ineffective. Sensitivity to psi-carba-NAD was found to parallel sensitivity to inhibition by isonicotinic acid hydrazide, another NADase inhibitor. psi-Carba-NAD is neither a substrate for nor an inhibitor of alcohol dehydrogenase, whereas carba-NAD is an efficient dehydrogenase substrate.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Department of Biochemistry, University of Texas Health Science Center, San Antonio 78284-7760.
authors.forename: J T
authors.initials: JT
authors.lastname: Slama
authors.forename: A M
authors.initials: AM
authors.lastname: Simmons
mesh_terms: D000429:Alcohol Oxidoreductases / Q000037:antagonists & inhibitors; D000818:Animals; D001921:Brain / Q000187:drug effects / Q000201:enzymology*; D002417:Cattle; D002772:Cholera Toxin / Q000494:pharmacology; D007700:Kinetics; D015394:Molecular Structure; D009699:N-Glycosyl Hydrolases / Q000037:antagonists & inhibitors*; D009243:NAD / Q000494:pharmacology*; D009244:NAD+ Nucleosidase; D009492:Neurospora crassa / Q000187:drug effects / Q000201:enzymology; D000067856:Poly(ADP-ribose) Polymerase Inhibitors; D011817:Rabbits; D012756:Sheep; D012911:Snakes; D013552:Swine
chemical_list: D000067856:Poly(ADP-ribose) Polymerase Inhibitors; D009243:NAD; D002772:Cholera Toxin; D000429:Alcohol Oxidoreductases; D009699:N-Glycosyl Hydrolases; D009244:NAD+ Nucleosidase