Actomyosin Ca++ Activated Adenosinetriphosphatase 활성도에 대한 pH 및 온도의 영향

• 영문명: pH-Temperature Dependence of the Ca-ATPase Activity in Actomyosin Systems of Rabbit and Frog Skeletal muscle
• 발행기관: 대한생리학회
• 저자명: 김희중(Kim, Hee-Joong) 황애란(Hwang, Ae-Ran) 박양생(Park, Yang-Saeng) 강두희(Kang, Doo-Hee)
• 간행물 정보: 『대한생리학회지』제11권 제2호, 1~8쪽, 전체 8쪽
• 주제분류: 의약학 > 의학일반
• 파일형태: PDF
• 발행일자: 1977.12.31

영문 초록

The activity of the Ca⁺⁺ activated adenosinetriphosphatase (Ca-ATPase) of actomyosin systeme of rabbit and frog skeletal muscle has been studied at varying pH and temperature. The PH optima of the Ca-ATPase activity of the rabbit actomyosin was rather broad. Over the temperature range of 16-36℃ activity of the enzyme was not appreciably changed between pH 6.4-8.5; below and above which it rapidly reduced. The pH at the inflection point of the enzyme activity increased as temperature decreased, showing the ΔpH inflection/ΔT of approximately -0.018 unit/℃. Consequently, (OH^-)/(H⁺) ratio at the inflection point was constant regardless of assay temperature. In the frog actomyosin systems the Ca-ATPase activity was not apparently altered between PH 6.4-7.0 when the incubation temperature was 15~30℃ . Outside of this range of pH, however, the enzyme activity was dramatically decreased. The pH of the inflection point changed inversely with temperature. ΔpH inflection/ΔT at the acidic side was approximately -0.018 unit/℃, whereas that at the alkaline side it was about -0.037 unit/℃. The Arrhenius Plot on the Ca-ATPase activity at constant (OH^-)/(H⁺) ratio of 1.0 was not linear, but showed break at arround 20℃ for both rabbit and frog actomyosin Preparations. From these results it was speculated that pH dependence of Ca-ATPase activity of rabbit actomyosin systems might reflect titrations of histidine-imidazole and -SH groups, and that of the frog actomyosin represents titrations of histidine-imidazole and lysyllysine α-NH₂ groups.