Heat resistance of MgATPase and contractility in muscle models

1. 1.|During the heating of a synthetic actomyosin suspension, the following sequence of events were observed. First, the rate of superprecipitation decreased; secondly the extent of superprecipitation decreased and finally the MgATPase activity was inhibited. At the same time the dissociating capability of actomyosin decreased in a solution of high ionic strength.

2. 2.|A similar lack of coincidence between the mechanical and the enzymatic activities of actomyosin was observed with an increasing proportion of inactivated myosin occurring in the reconstructed actomyosin complex.

3. 3.|The different heat resistance of contractility and MgATPase activity in muscle models may be caused by inactivated myosin bridges which form in the course of heat treatment so that the dissociating capacity of actomyosin in the presence of ATP is lost.

Author Keywords: heat resistance of mucle models; actomyosin ATPase; actomyosin superprecipitation; myosin bridges