SPIN-LABEL STUDIES ON THE ORIGIN OF THE SPECIFICITY OF LIPID PROTEIN INTERACTIONS IN NA+,K+-ATPASE MEMBRANES FROM SQUALUS-ACANTHIAS
SPIN-LABEL STUDIES ON THE ORIGIN OF THE SPECIFICITY OF LIPID PROTEIN INTERACTIONS IN NA+,K+-ATPASE MEMBRANES FROM SQUALUS-ACANTHIAS
复制标题
DOI：
10.1021/bi00335a027
复制
发表时间：
1985-01-01
期刊：
影响因子：
2.9
通讯作者：
MARSH, D
中科院分区：
文献类型：
--
作者：
ESMANN, M;MARSH, D
研究了磷脂酸、磷脂酰丝氨酸和硬脂酸与S.用自旋标记的电子自旋共振光谱法研究了棘皮症，使用在sn-2链的14位C原子上具有氮氧标记的脂质。对于磷脂酸和硬脂酸，运动限制自旋标记的分数随pH值的增加而增加，pKa分别为6.6和8.0。相比之下，硬脂酸在膜的本体脂质环境中的pKa由自旋标记光谱法估计为6.6.运动受限的磷脂酰丝氨酸自旋标记的磷脂酸和硬脂酸的分数随着盐浓度的增加而减少，在[NaCl] = 0.5-1.0 M时达到近似恒定值。对于硬脂酸，净减少与质子化获得的净减少相当，但对于磷脂酸，减少小得多（约为0.05）。55%）。运动限制的磷脂酰丝氨酸自旋标记的分数变化相对较小的盐浓度高达1 M NaCl。单独的直接静电效应不能解释所观察到的2种磷脂与Na+，K+-ATP酶膜相互作用的全部特异性。
The pH dependence and salt dependence of the lipid-protein interactions of phosphatidic acid, phosphatidylserine and stearic acid with Na+, K+-ATPase membranes from S. acanthias were studied with spin-labeled electron spin resonance spectroscopy, using lipids with nitroxide labels on the 14-position C atom of the sn-2 chain. For phosphatidic acid and stearic acid, the fraction of motionally restricted spin-label increases with increasing pH, with pKa of 6.6 and 8.0, respectively. In contrast, the pKa of stearic acid in the bulk lipid environment of the membrane is estimated from spin-label spectroscopy to be .apprxeq. 6.6. The fraction of motionally restricted phosphatidylserine spin-labeled phosphatidic and stearic acids decrease with increasing salt concentration, reaching an approximately constant value at [NaCl] = 0.5-1.0 M. For stearic acid the net decrease is comparable to that obtained on protonation, but for phosphatidic acid the decrease is considerably smaller (by .apprx. 55%) than that obtained on protonating the lipid. The fraction of motionally restricted phosphatidylserine spin-label varies relatively little with salt concentration up to 1 M NaCl. Direct electrostatic effects alone cannot account for the whole of the observed specificity of interaction of the 2 phospholipids with Na+, K+-ATPase membranes.