PURIFICATION AND PROPERTIES OF PROTEIN-KINASE-C FROM BOVINE POLYMORPHONUCLEAR LEUKOCYTES

A calcium-activated, phospholipid-dependent protein kinase (protein kinase C) was purified to near homogeneity from bovine polymorphonuclear leucocytes. The purified enzyme had a specific activity of 10,000 U/mg protein and on SDS gelelectrophoresis the Mr was 88000. The enzyme activity was almost totally dependent upon phosphatidylserine and could be strongly activated by Ca2+ concentrations in the micromolar range. At lower concentrations of calcium (less than 1 .cntdot. 10-7 M) the enzyme was only activated by the simultaneous presence of phosphatidylserine and diolein. Phorbol 12-myristate 13-acetate mimicked the effect of diolein and partially activated the enzyme. Protein kinase C activity and the phorbolester binding protein co-purified throughout all the purification steps.