磷脂酰胆碱对兔骨骼肌肌质网钙泵磷酸化微区分子运动的影响

EFFECT OF PHOSPHATIDYLCHOLINES ON THE DYNAMIC MICROSTRUCTURE OF PHOSPHORYLATION DOMAIN OF Ca^(2-)-ATPase FROM RABBIT SARCOPLASMIC RETICULUM

用毫微秒荧光分光光度计研究了精制兔骨骼肌肌质网钙泵的分子内微细结构及周围磷脂对分子内运动状态的影响.磷脂酰胆碱的置换,导致钙泵脂酶体膜微粘度下降,磷脂分子运动增强,膜流动性增加.di(20:4)PC置换基本未改变钙泵分子内磷酸化微区(Domain)的运动状态.短链磷脂置换使钙泵酸化微区运动加速.结果提示,磷脂分子的平均链长是影响钙泵酸化微区运动状态的重要因素;不饱和度对分子内运动几无影响.

With a nanosecond time -resolved fluorometer. the effect of phospholipids on the intramolecular dynamic microstructure of Ca2+-ATPase form rabbit sarcoplasmic reticulum was studied. Ca2+-ATPase was purified and reconstituted into vesicles and phospholipids surrounding the hydrophobic segment of Ca26-ATPase were exchanged with phosphatidylcholines of longer acyl chain length by lipid titration. The results showed that the replacement could lead to a decrease in membrane viscosity and Ca2+-ATPase activity. The half-decay tune of ANM fluorescence anisotropy was 72 ± 4ns in the control vesicles. 67± 3ns in di(20:4)PC titration vesicles. Concomitantly. observed decreases in membrane viscosity and Ca2+-ATPase activity suggest that the decreased membrane viscosity destabilized the Ca2+ -ATPase protein structure causing a reduction in Ca2+-ATPase activity.