[Mechanism of temperature uncoupling of the sarcoplasmic reticulum calcium pump: change in the functional properties and structural state of the enzyme molecule].

The effect of short-term thermal treatment causing the uncoupling of the hydrolytic and transport functions of skeletal muscle sarcoplasmic reticulum Ca-ATRase on the conformational state of the enzyme and the physico-chemical characteristics of the membrane lipid bilayer has been studied. It has been found that enhanced passive permeability of the membrane for Ca2+ is the main cause for the decreased efficiency of the Ca-pump function. Thermal treatment induced no changes in the conformation of the hydrophilic domain of the Ca-ATRase; however, the accessibility of the transmembrane hydrophobic domain for some solutes turned out to be restricted, the microviscosity of the lipid bilayer decreased and the protein-lipid and protein-protein interactions within the membrane disturbed after the heat exposure.