家兎골격근小胞體切片의 ATPase 에 관한 硏究

Studies on the ATPases of Fragmented Sarcoplasmic Reticulum of Rabbit Skeletal Muscle

토끼의 골격근 小胞體 切片을 遠心分離하여 그 ATPase 活性의 生化學的性質을 $Mg^++ - ATPase 와 (Mg^++ - Ca^++)$-ATPase로 구분하여 조사하였다. $(Mg^++ - Ca^++)$-ATPase의 活性은 $0^\\circ - 40^\\circ C$의 범위, 그리고 pH 6.4-7.6의 범위에서는 $Mg^++$-ATPase보다 훨씬 높다. 이 현상은 온도가 높을수록 더욱 현저하다. 活性化에너지는 온도 $0^\\circ -40^\\circ C$의 범위에서는 $Mg^++$-ATPase가 14kcal/mole, $(Mg^++ - Ca^++)$-ATpase 가 21kcal/mole, 그리고 total ATPase 가 18kcal/mole 이다. 이 活性化에너지의 값은 pH와 Mg 濃度에 무관하다. 이들 효소의 Km의 값은 $Mg^++$-ATPase 가 0.36mM , $(Mg^++ - Ca^++)$-ATpase가 2.20mM, 그리고 total ATPaserk 0.86 mM이다.

Fragmente dsarcoplasmic reticulum of rabbit skeletal muscle was prepared and biochemical properties of its ATPase activity were studied. The ATPase of the fragments could be distinguished as $Mg^++ - ATPase and (Mg^++ - Ca^++)$-ATPase. The activity of $(Mg^++ - Ca^++)$-ATPase was predominant over that of $Mg^++$-ATPase in the temperature range of $0 \\sim 40^\\circ C$ and in the pH 6.4$\\sim$7.6. At higher temperatures the predominance of $(Mg^++ - Ca^++)$-ATpase was far greater. The apparent energies of activation were 14 kcal/mole for $Mg^++$-ATPase, 21kcal/mole for $(Mg^++ - Ca^++)$-ATPase, and 18kcal/mole for total ATPase. Changes in pH and Mg concentration did not alter the energies of activation of these ATPases. The Km values of these ATPases were found to be 0.36 mM for $Mg^++$-ATPase, 2.20 mM for $(Mg^++ - Ca^++)$-ATpase, and 0.86 mM for total ATPase.