Mühlrad, A. & Ferencz, K.

Studies on the properties of chemically modified actin IV: activation of myosin ATPase by actin and trinitrophenylated actin.

Physiol Chem Phys 5, 13-26.

Faragó, A., Antoni, F., Takáts, A. & Fábián, F.

Adenosine 3':5'-monophosphate-dependent and independent histone kinases isolated from human tonsillar lymphocytes.

Biochim Biophys Acta 297, 517-26.

Bíró, E. N. A., Szilágyi, L. & Bálint, M.

Studies on the helical segment of the myosin molecule.

Cold Spring Harbor Symp Quant Biol 37, 50-63.

Bíró, E. N., Coelho, R., Ehrlich, E., Guillain, F. & Dvonc, C.

Preparation of the enzymatically active subfragment of myosin by proteolysis of myofibrils.

Eur J Biochem 40, 527-31.

Myofibrils, when submitted to proteolysis, yield several fragments, some of which remain bound to actin. There are separated by pyrophosphate treatment and isolated by preparative centrifugation. When trypsin treatment is performed in the presence of 1 mM CaCl2, two types of products are obtained, which can be separated by chromatography on DEAE-cellulose. However, when proteolysis is performed with 10 mM EDTA in the medium, only one enzymatically active fragment is isolated. It is characterized by its sedimentation coefficient, α-helix content, amino-acid composition, actin-binding properties in the absence of ATP and actin-activation of its enzymatic activity. It is thus shown that the EDTA type fragment is similar to heavy-mero-myosin subfragment 1 obtained by direct treatment of myosin or heavy meromyosin with papain or trypsin.