Adenyl cyclase. II. The enzymatically catalyzed formation of adenosine 3',5'-phosphate and inorganic pyrophosphate from adenosine triphosphate.

Earlier studies have shown that enzyme preparations from a number of tissues are capable of forming small amounts of adenosine 3’) 5’-phosphate (cyclic 3’) 5’-AMP) from adenosine triphosphate (l-3). This nucleotide has been found to have important biological properties, which recently have been reviewed in detail (4, 5). In Paper I of this series attempts to fractionate or to simplify enzyme preparations capable of forming cyclic 3’,5’-AMP (termed adenyl cyclase) are described (6). Although only modest success was achieved, it was possible to use certain particulate or solubilized preparations to begin study of the reactants and products in the reaction forming cyclic 3’, 5’-AMP. This report is chiefly concerned with evidence for the formation of inorganic pyrophosphate concomitant with the formation of cyclic 3’,5’-AMP. In addition, evidence indicating that the a-phosphate of adenosine triphosphate is the precursor of the phosphate of cyclic 3’) 5’-AMP is presented.