Hydrolysis of Ribonucleoside 2’) 3’-Cyclic Phosphates by a Diesterase from Brain*

Enzymes that are capable of hydrolyzing ribonucleoside 2’, 3’cyclic phosphates but that do not attack intemucleotide bonds are available from various sources (1). Several of these enzymes convert ribonucleoside 2’,3’-cyclic phosphates to the corresponding ribonucleoside 2’-phosphates. The first die&erase of this type was studied in calf spleen by Whitfeld, Heppel, and Markham (2). Davis and Allen (3) later described a highly specific enzyme from beef pancreas that converted purine and pyrimidine 2’,3’-cyclic phosphates to the 2’-phosphates. In a previous report from this laboratory (4), it was briefiynoted that rabbit brain extracts catalyzed a rapid hydrolysis of these compound8 and that the product of hydrolysis of adenosine 2’,3’-cyclic phosphate was adenosine 2’-phosphate. This paper describe8 further studies concerning the properties and the specificity of this enzyme in the central nervous system.