[Changes in properties of actomyosin in the process of ontogenesis]

The paper deals with some data on nonidentical heat-resistance of actomyosin of the skeletal muscles and myocardium of the calf foetus and adult animals. It is shown that in the process of uterine development the ATPase activity increases and at alkaline pH the Ca2+-activated ATPase of natural actomyosin of the cattle skeletal muscles and myocardium is activated. Heat-resistance of ATPase of the skeletal muscles and myocardium decreases with age, the myocardium actimyosin ATPase being more stable to heating. These denatured changes are found to be of a reversible character.