Davoust J, Schoot B M, Devaux P F
Proc Natl Acad Sci U S A. 1979 Jun;76(6):2755-9. doi: 10.1073/pnas.76.6.2755.
The microviscosity of rhodopsin boundary lipids was studied with a spin-labeled fatty acid covalently attached to rhodopsin, in rhodopsin-egg lecithin vesicles. When the lipid-to-protein ratio was high (500:1, mole to mole), only narrow peaks were visible in electron paramagnetic resonance spectrum at 37 degrees C. This enabled us to show that, under these conditions, not more than 10% of the probes have their motion strongly restricted by the proximity of the protein. When the temperature was reduced, a second component characteristic of strong immobilization appeared. It corresponds to 50% of the signal at -5 degrees C. At all temperatures reduction of the lipid-to-protein ratio also resulted in an increase of the amount of immobilized lipid. These results show that the rhodopsin boundary layer under physiological conditions is associated with low microviscosity. However, low temperatures, low lipid-to-protein ratios, or combinations of the two can induce dramatic modifications of the physical state of the boundary lipids, which under these conditions may no longer be representative of the functional biological system. These results are relevant to the general theory of lipid-protein interaction.
在视紫红质 - 卵磷脂囊泡中，使用共价连接到视紫红质的自旋标记脂肪酸研究视紫红质边界脂质的微粘度。当脂质与蛋白质的比例很高时（摩尔比为500:1），在37摄氏度的电子顺磁共振谱中仅可见狭窄的峰。这使我们能够表明，在这些条件下，不超过10%的探针由于靠近蛋白质而其运动受到强烈限制。当温度降低时，出现了第二个强烈固定化的特征成分。在-5摄氏度时，它对应于50%的信号。在所有温度下，脂质与蛋白质比例的降低也导致固定化脂质数量的增加。这些结果表明，在生理条件下视紫红质边界层与低微粘度相关。然而，低温、低脂质与蛋白质比例或两者的组合可引起边界脂质物理状态的显著改变，在这些条件下，边界脂质可能不再代表功能性生物系统。这些结果与脂质 - 蛋白质相互作用的一般理论相关。
