Enzymatic Degradation of Adenosine Triphosphate to Adenine by Cabbage Leaf Preparations.

Apyrases, enzymes which hydrolyze ATP (adenosine triphosphate to form AMP (adenylic acid) and orthophosphate, have been described in potato (11) and citrus fruits (1). A phosphatase which will specifically dephosphorylate AMP has been found in potato (18); however, non-specific phosphatases will also dephosphorylate this compound (2). Enzymes specifically dephosphorylating yeast adenylic acid (A3P) are known in rye grass, wheat leaves, and barley (31). Nucleosidases which will hydrolyze adenosine to adenine have been demonstrated in potato (7), in wheat (29), and in soy bean leaves (22). This paper describes the enzyme complex in the cytoplasm of cabbage leaves which is capable of the breakdlown of ATP to adenine. The route of breakdown appears to procee(l to AMP by an apyrase reaction, followed by a dephosphorylation andl hydrolysis to yield adenine. Two apyrases are present in the cytoplasm. An apyrase associated with the washed cytoplasmiiic particles has been foundl that is distinct from the apyrases of the soluble fraction.