STUDY ON ATPASE AND REGULATORY PROPERTIES OF SKELETAL-MUSCLE MYOSIN OF GROUND-SQUIRRELS (CITELLUS-UNDULATUS) AT DIFFERENT STAGES OF HIBERNATION

The paper is devoted to the study on enzymatic and regulatory properti es of skeletal muscle myosin or hibernating ground squirrels (Citellus undulatus) for the purpose of elucidating the contribution of myosin and myosin filaments to the change of physiological state of the anima l at the different stages of hibernation (hibernation, arousing, winte r activity). It has been revealed that actin-activated ATPase activity of myosins of hibernating and arousing ground squirrels is less by 60 and 20%, correspondingly, than that of the myosin of active animals. In the absence of troponin-tropomyosin complex the Ca2+-sensitivity of actomyosins of the hibernating and arousing ground squirrels is less by 60 and 55%, correspondingly, than that of the actomyosin of active animals. The results obtained by us point to the essential decrease of functional properties of the main contractile protein, myosin upon hi bernation, which evidently contributes to the inhibition of moving cap acity of skeletal muscles at this period.