Inhibition of bovine and human brain 2':3'-cyclic nucleotide 3'-phosphodiesterase by heparin and polyribonucleotides and evidence for an associated 5'-polynucleotide kinase activity.

Abstract The present paper establishes a 5′-polynucleotide kinase activity associated with the bovine and human brain enzyme 2′:3′-cyclic nucleotide 3′-phosphodiesterase (EC 3.1.4.37) in addition to known extremely high hydrolysis rates against 2′:3′-cyclic nucleotides. Modulation of the enzyme activity by the addition of polyadenylate (5′) and polyuridylate (5′), histone F3 , myelin basic protein (MBP), and other basic molecules suggest that RNA may be the natural substrate for both enzymes. These enzymes, isolated from brain and present in very high activities in oligodendrocytes and in isolated myelin, probably have complex functions.