[Skeletal muscle troponin and phosphorylation: a site of troponin T, that is phosphorylated by specific protein kinase].

A procedure is described of the isolation of protein kinase, which phosphorylates isolated troponin T with a rate, 5--30 fold exceeding the phosphorylation rate of other substrates (phosvitine, caseine, protamine sulphate, H1, H2A, H2b, H3, H4 histones). Troponin T-specific protein kinase transfers 0.85--0.95 moles of P per 1 mol of dephosphorylated troponin T. It phosphorylates only N-terminal acetylated serine residue, i. e. the site of troponin T structure, which is normally phosphorylated, when the whole troponin complex is isolated from skeletal muscles. Protein kinase is incapable to phosphorylate N-terminal serine residue in a mixture of triptic peptides of troponon T.