Natural Occurrence and Enzymatic Synthesis of α-Nicotinamide Adenine Dinucleotide Phosphate

A pyridine nucleotide has been synthesized from α-nicotinamide adenine dinucleotide and adenosine triphosphate with the use of a crude enzyme preparation from Azotobacter vinelandii strain O. Evidence is presented that this nucleotide is the α isomer of NADP, α-NADP, which differs from β-NADP in the configuration of the nicotinamide-ribosidic linkage. This evidence rests on a study of (a) spectral properties, (b) degradation by snake venom phosphodiesterase followed by comparison with authentic samples, (c) stability of the nicotinamide-ribonucleosidic linkage in acid, and (d) optical rotatory dispersion. In contrast to β-NADP, α-NADP is not active with yeast glucose 6-phosphate dehydrogenase, nor is it cleaved by Neurospora crassa NAD glycohydrolase. α-NADP has been shown to be present in the cells of A. vinelandii; about 1:10 has been found for a normal equilibrium molar ratio of α-NADP to β-NADP.