Cyclic Nucleotide-dependent Protein Kinases

Abstract

An adenosine3',5'-monophosphate-dependent protein kinase, which catalyzes the phosphorylation of histone by ATP, has been purified from bovine brain and some of its properties have been studied.Under appropriate conditions, the activity of the enzyme was stimulated more than ZO-fold by adenosine 3',5'-monophosphate, with an apparent K, for the cyclic nucleotide of about 2.5 X 10e7 M. The activation of the enzyme by adenosine 3', 5'-monophosphate was associated with a decrease in K, of the enzyme for ATP that occurred in the presence of the cyclic nucleotide.In contrast, adenosine 3',5'-monophosphate had no significant effect on the K, of the enzyme for the histone.The optimum pH for the activity of the enzyme was 6.5.The purified enzyme had an absolute requirement for a divalent metal.The stimulation by cyclic AMP was greatest in the presence of Mg+f, Mn++, or Co++.Cyclic AMP strongly inhibited enzyme activity in the presence of Ca++.The activation observed in the presence of adenosine 3',5'monophosphate was also observed with the 3',5'-monophosphate derivatives of inosine, guanosine, uridine, and cytidine as well as with dibutyryl adenosine 3',5'-monophosphate, but much higher concentrations of these other cyclic nucleotides were required.Deoxythymidine 3', 5'-monophosphate, the only cyclic deoxyribonucleotide studied, was completely inactive.Adenosine and ADP were inhibitors of the enzyme.