[Purification and biochemical characteristics of myosin from rat malignant sarcoma-45].

Myosin was purified from rat tumour sarcoma-45 whose properties (effects of cations on ATPase activity, substrate specificity, temperature- and pH-optima, thermal stability, sensitivity of Mg2(+)-ATPase to F-actin, molecular mass, subunit composition) are similar to those of fast skeletal muscle myosin. Some parameters of the protein, namely, the levels of Ca2(+)- and K+, EDTA-ATPase activity, relative content of myosin light chains with Mr 16500 and the degree of tumoural myosin Mg2(+)-ATPase activation by F-actin, were significantly lower than those of skeletal muscle myosin.