Reduced nicotinamide 8-(alkylamino)adenine dinucleotides: enzyme-coenzyme interactions with different adenyl glycosyl bond conformations.

Enzyme binding studies have been conducted on several reduced nicotinamide adenine dinucleotide analogues having different substitutions at the 8 position of the adenine. The following analogues were synthesized for this study: 8-bromo-, 8-(methylamino)-, 8-(dimethylamino)-, and 8-(ethylamino)-substituted NADH. The conformation of these analogues was also studied. 1H and 13C nuclear magnetic resonance analysis showed that there was rotation about the adenine glycosyl bond and that the rotational preference depended on the C8 substituent. The bromo and dimethylamino analogues were predominantly in the syn conformation, while the anti conformation prevailed in the other derivatives as it does in the native NADH. Use of these analogues as co-enzymes by Pseudomonas aeruginosa transhydrogenase, Beneckea harveyi FMN:NADH oxidoreductase, rabbit muscle lactate dehydrogenase, beef heart lactate dehydrogenase, horse liver alcohol dehydrogenase, and yeast alcohol dehydrogenase resulted in enzyme activity in all cases. The bromo and dimethylamino analogues were bound significantly tighter than the other analogues for at least two of the enzymes studied. The data are discussed with respect to the ability of these enzymes to bind nucleotides which are in the syn conformation.