Nicotinamide 1,N6-ethenoadenine dinucleotide (epsilon-NAD) is a fluorescent analog of NAD. Nicotinamide 1,N6-ethenoadenine dinucleotide can be cleaved by phosphodiesterase I (from C. adamanteus venom) and binds to bovine liver glutamate dehydrogenase. Nicotinamide 1,N6-ethenoadenine dinucleotide can serve as a substrate for G-ADP ribosylation of G proteins catalyzed by bacterial toxins. Nicotinamide 1,N6-ethenoadenine dinucleotide can be used as a fluorescent substrate for the study of ADP ribosylation reactions[1][2].