Calcium ion과 ATP 에 의해 기질선택성이 조절될 수 있는 Phosphatidylinositol - specific phospholipase C 에 대한 연구 = Studies on the Substrate Selectivity of Phosphatidylinositol - Specific Phospholipase c possibly Regulated by Calcium Ion and ATP

다국어 초록 (Multilingual Abstract)

Previously reported mouse brain cytosolic PI-phospholipase C (Kim et at., 1987) showed the selectivity of substrates, such as, ³H-PI and ³H-PIP₂ was possibly regulated by the concentration of Ca^(2+) and ATP at the optimum pH 5.0 and physiological pH 7.2. The enzymatic hydrolysis of PIP₂ at pH 5.0 and pH 7.2 without Ca^(2+) represented about 4 and 8 times higher than PI, respectively. In this condition, PI showed very low hydrolysis. As increase the Ca^(2+) concentrations, the hydrolysis of PI at both pH 5.0 and pH 7.2 showed steady increase until 5 mM Ca^(2+) concentration. On the other hand, the hydrolysis of PIP₂ at pH 5.0 showed a little increase until 1 mM Ca^(2+) concentration and decreased after that. And also, the similar result was obtained at pH 7.2 with 0.2 mM Ca^(2+) concentration. In the effect of ATP on the hydrolysis of PI and PIP₂ at the physiological pH 7.2, PI hydrolysis was not affected at all without Ca^(2+), but it was significantly decreased over 10^(-5)M ATP concentration with 1 mM Ca^(2+). In the case of PIP₂ATP showed 100% stimulation with 10^(-3)M ATP in the absence of Ca^(2+), and 150 % with 10^(-2)M ATP in the presence of 1 mM Ca^(2+), respectively.