Polynucleotide phosphorylase of Micrococcus lysodeiktpcus. III. The apparent arsenolysis of nucleoside diphosphates by polynucleotide phosphorylase.

The enzyme, polynucleotide phosphorylase, catalyzes the polymerization of nucleoside diphosphates to polyribonucleotides with the formation of inorganic orthophosphate (1, 2). The reaction is readily reversible, and the phosphorolysis of polyribonucleotides has been studied extensively (3-6). Several recent reviews (7-9) afford extensive summaries of the literature. In the accompanying paper (lo), we demonstrated that arsenate can replace Pi as a substrate for the enzyme, and the arsenolysis of polyribonucleotides is described therein. The work of Grunberg-Manago, Ortiz, and Ochoa (1) and Littauer and Kornberg (2) showed that polynucleotide phosphorylase also catalyzes an apparent exchange reaction between nucleoside diphosphate and Pi3’ (Equation 1).