Chakrabarti A K, Dasgupta S, Banik N L, Hogan E L
Department of Neurology, Medical University of South Carolina, Charleston 29425.
Biochim Biophys Acta. 1990 Apr 19;1038(2):195-8. doi: 10.1016/0167-4838(90)90204-s.
Since calcium-activated neutral proteinase (CANP; calpain) activation occurs at the plasmalemma and the enzyme is found in myelin, we examined myelin lipid activation of brain CANP. Purified lipids were dried, sonicated and incubated with purified myelin CANP. The CANP was assayed using [14C]azocasein as substrate and the Ca2+ concentration ranged from 2 microM for muCANP to 5 mM for mCANP. Phosphatidylinositol (PI), phosphatidylserine (PS) and dioleoylglycerol stimulated the mCANP activity by 193, 89 and 78%, respectively. PI stimulated both m- and muCANP in a concentration-dependent manner, while phosphatidylcholine was least effective. Cerebroside and sulfatide at higher concentrations (750 microM) were stimulatory. The phospholipid (PL)-mediated activation was inhibited by the PL-binding drug trifluoperazine. PI reduced the Ca2+ requirement for CANPs significantly (20-fold). These results suggest that acidic lipids and particularly acidic phospholipids activate membrane CANP.
由于钙激活中性蛋白酶（CANP；钙蛋白酶）的激活发生在质膜上，且该酶存在于髓磷脂中，因此我们研究了脑CANP的髓磷脂脂质激活作用。将纯化的脂质干燥、超声处理并与纯化的髓磷脂CANP一起孵育。使用[14C]偶氮酪蛋白作为底物测定CANP，Ca2+浓度范围从用于μCANP的2微摩尔到用于mCANP的5毫摩尔。磷脂酰肌醇（PI）、磷脂酰丝氨酸（PS）和二油酰甘油分别使mCANP活性提高了193%、89%和78%。PI以浓度依赖的方式刺激mCANP和μCANP，而磷脂酰胆碱的效果最差。高浓度（750微摩尔）的脑苷脂和硫脂具有刺激作用。磷脂（PL）结合药物三氟拉嗪抑制了PL介导的激活。PI显著降低了CANP对Ca2+的需求（20倍）。这些结果表明酸性脂质，尤其是酸性磷脂可激活膜CANP。
