Abstract
The present paper describes the purification and characterization of the soluble protein kinases from erythrocytes of the bullfrog, Rana catesbeiana. The results obtained are as follows:
1) Two cAMP-dependent protein kinases, FI and FII, were partially purified from the cytosol of the bullfrog erythrocytes by use of a DEAE-cellulose chromatography and an affinity chromatography on Sepharose 4 B coupled with histone-II A. Based upon chromatographic behavior on DEAE-cellulose, FI was referred to as type I and FII as type II protein kinase, respectively.
2) Molecular weight was estimated to be 160, 000 for FI and 125, 000 for FII by gel filtration, respectively.
3) The two purified enzymes resembled each other in the following enzymatic properties, binding activity of the enzymes by cAMP, stimulation of enzymatic activity by cAMP which was most effective in the cyclic nucleotides examined, high substrate specificity for histone, requirement of Mg2+ for full enzyme activity, the apparent Km (1 x 10-5M) for ATP which was independent on cAMP, cAMP dependent increase in the maximum velocity, and the optimal pH of 7.5.8.0. These properties of the protein kinases from bullfrog erythrocytes also resemble those of the cAMP-dependent protein kinases found in various mammalian tissues.
4) The tadpole erythrocyte supernatant showed a cAMP-independent but not cAMPdependent protein kinase activity.
