A method for isolation of troponin T kinase (ATP-protein phosphotransferase, EC 2.7.1.37) from rabbit skeletal muscles in proposed. The method gives a 7000-10 000-fold purification and results in an enzyme with specific activity of 400-800-nmol x min-1 x mg-1 of protein. The molecular weight of tropin T kinase as determined by gel filtration exceeds 500 000. Electrophoresis in polyacrylamide gel in the presence of sodium dodecyl sulphate revealed that isolated preparations of the enzyme consisted of at least three distinct proteins with apparent mol.wt. of 50 000, 46 000 and 31 000. The enzyme phosphorylates isolated troponin T at a rate which exceeds the phosphorylation rates of casein, phosvitin, histones, phosphorylase b and protamine 5-30-fold. Within the whole troponin complex, only troponin T is phosphorylated by the enzyme. The enzyme phosphorylates only the N-terminal serine residue of troponin T, i.e. the site that is normally phosphorylated in the whole troponin complex isolated from rabbit skeletal muscles.

Rabbit skeletal-muscle troponin T was phosphorylated by a standard preparation of phosphorylase kinase [Cohen (1973)

One method to increase the efficacy ofthrombolytic therapy consists in using a combination of plasminogen activators [1,2]. This approach may reduce the frequency of complications after thrombolysis, allow a decrease in the total dose of the drugs introduced, accelerate the drug action compared to the case of monotherapy, and lower the costs of the course of therapy [1][2][3][4][5]. In order to develop this approach, we have previously synthesized and studied in vivo the preparations of different plasminogen activators producing mutually complementary effects [6,7] and possessing significantly differing pharmacokinetic profiles [8]. Experiments on the model of venous thrombosis in dogs revealed the phenomenon of fast response for the combined administration of the recombinant tissue plasrninogen activator (TPA) and a fibrinogen-modified urokinase-fibrinogen (UK-Fbg) conjugate, although these results were achieved using a rather prolonged and complicated bolus-infusion-bolus administration schedule [9]. Recent experiments in vitro also justified expediency of the further investigation of the thrombolytic t Cardiological Research and Production Complex, Ministry of Health and Medical Industries of the Russian Federation, Moscow, Russia.

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