Prepd by incubation of NAD with potato pyrophosphatase in a non-phosphate buffer and in the presence of fluoride: Plaut, Plaut, Arch. Biochem. Biophys. 48, 189 (1954); Biochem. Prep. 5, 55 (1957). Enzymatic synthesis from nicotinamide by human erythrocytes and hemolyzates: Preiss, Handler, J. Biol. Chem. 225, 759 (1957). Prepn by hydrolysis of NAD by a yeast enzyme: Takei, Agric. Biol. Chem. 34, 23 (1970); by cleavage of NAD with crude rattlesnake venom: Apps, FEBS Lett. 15, 277 (1971); R. Jeck, C. W"onckhaus, Methods Enzymol. 66, 62 (1980). NMR studies and conformation of α- and β-nicotinamide nucleotide: N. J. Oppenheimer, N. O. Kaplan, Biochemistry 15, 3981 (1976).