[Effects of neutral salts and temperature on skeletal muscle sarcolemmal Ca-TPase].

The temperature dependence and effects of sodium and potassium chloride on purified preparations of sarcolemmal Ca2+-activated ATPase were investigated. It was shown that within the concentration range of 0,1--1,0 M both salts have the same effect on the enzyme activity. A low ionic strength and concentration of the salts of 0,1 M the temperature maximum was 45 degrees and the shapes of temperature curves were the same. The Arrhenius plots showed a break at 16--19 degrees. The apparent activation energies were 27,3 kcal/mole below and 17,1 kcal/mole above the break point. At high ionic strength (0,5 M) the temperature maximum was observed at 40 degrees and the apparent activation energies decreased down to 18,0 kcal/mole below and 11,5 kcal/mole above the break point.