Diphosphopyridine nucleotidases (DI'Nases)' of t,he so called glycosidase type, which catalyze cleavage of the ribose-nicotinamide bond in DPN, have been known for a long time to be associated with the insoluble particles of cells. The enzyme, which was first detected in 1929 (3-5) and which was shown by Mann and Quastel (6) and Handler and Klein (7) to cleave the ribose-nicotinamide bond in DPN, was also shown by these authors to be firmly attached to cell particles. Subsequent investigations

more »

... 8-10) have confirmed this view. Previous attempts to render the enzyme soluble, e.g. by McIlwain (8) , were either unsuccessful or resulted in very poor yield. Likewise, Alivisatos, Kashket, and Denstedt (11) were able to obtain in solution only 0.2 per cent of the enzyme from stroma of rabbit erythrocytes treated by the Morton method (12) with n-butanol. As a preliminary to the use of this enzyme in dinucleotide synthesis (13), it was desirable to purify it. Solubilization t.hus became necessary. This was accomplished by treatment of cell fragments with isoamyl alcohol and a solution of deoxyribonucleic acid (DNA). The soluble enzyme was then purified by conventional methods.