Chen Q P, Li Q T
Department of Biochemistry, Faculty of Medicine, National University of Singapore, 10 Kent Ridge Crescent, Singapore 119260.
Arch Biochem Biophys. 2001 May 15;389(2):201-6. doi: 10.1006/abbi.2001.2319.
The effect of cardiolipin on the proton permeability of dipalmitoyl-phosphatidylcholine small unilamellar vesicles was examined by utilizing the pH-dependent fluorescence emission of 5- (and 6-) carboxyfluorescein. It has been found that the proton permeability of the phospholipid bilayer was greatly enhanced in the presence of cardiolipin, an acidic phospholipid mainly found in the inner mitochondrial membranes. In the presence of bovine heart cardiolipin, the bilayer surface hydration, as assessed with the fluorescence lifetime of 1-anilinonaphthalene-8-sulfonic acid, was increased, while hydration in the acyl chain region was not altered. In addition, the bilayer fluidity was also not affected. Taken together, these results suggest that the lipid-water interface is the major energy barrier for proton permeation of the bilayer vesicles, and alteration to properties of this interface by cardiolipin headgroup appears to be responsible for the enhanced proton permeability.
利用5-（及6-）羧基荧光素的pH依赖性荧光发射，研究了心磷脂对二棕榈酰磷脂酰胆碱小单层囊泡质子渗透性的影响。已发现，在心磷脂（一种主要存在于线粒体内膜的酸性磷脂）存在的情况下，磷脂双层的质子渗透性大大增强。在用1-苯胺基萘-8-磺酸的荧光寿命评估时，在牛心磷脂存在的情况下，双层表面水合作用增加，而酰基链区域的水合作用未改变。此外，双层流动性也未受影响。综上所述，这些结果表明脂质-水界面是双层囊泡质子渗透的主要能量屏障，心磷脂头部基团对该界面性质的改变似乎是质子渗透性增强的原因。
