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

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.