The Preparation and Properties of IV-Hydroxyethyl Derivatives of Adenosine, Adenosine Triphosphate, and Nicotinamide Adenine Dinucleotide*

Previous work shows that replacement of the nicotinamide moiety of nicotinamide adenine dinucleotide with other substituted pyridines leads to a useful series of analogues of this coenzyme (3, 4). The present communication describes the preparation and properties of a different series of analogues obtained by systematic modification of the adenine moiety of NAD. The only adenine-modified analogue previously described is nicotinamide hypoxanthine dinucleotide, which can be prepared from NAD by either chemical (5) or enzymatic deamination (6). This compound shows widely varying ability to function as a coenzyme in a series of enzymatic dehydrogenations (7) and, after reduction, fails to exhibit spectrofluorometrically detectable intramolecular energy transfer from the purine to the dihydronicotinamide moiety, as is exhibited by NADH (8). To gain more insight into the role of the adenine nitrogen atoms of NAD in the coenzymatic and energy transfer capabilities of the molecule, N-alkylation has been undertaken. Ethylene oxide was select,ed as the alkylating agent after earlier studies had revealed that under very mild conditions this agent readily hydroxyethylates tertiary heterocyclic nitrogen atoms but not hydroxyl groups (9, 10). The reactions of ethylene oside with adenosine and with adenosine triphosphate were examined first, to serve as models for the hydroxyethylation of NAD and to compare the reactivity of primary and secondary phosphate groups to that of adenine. Stacey et al. have reported that in the reaction of nucleic acids with epoxides, the predominant reaction is the esterification of