Dynamic imaging of lateral diffusion by electron spin resonance and study of rotational dynamics in model membranes. Effect of cholesterol.
Dynamic imaging of lateral diffusion by electron spin resonance and study of rotational dynamics in model membranes. Effect of cholesterol.
复制标题
通过电子自旋共振进行横向扩散的动态成像以及模型膜中旋转动力学的研究。
DOI：
10.1016/s0006-3495(89)82847-4
复制
发表时间：
1989
影响因子：
3.4
通讯作者：
Freed,JH
中科院分区：
文献类型：
--
作者：
Shin,YK;Freed,JH
研究了胆固醇对POPC/胆固醇取向多层模型膜中两种不同自旋探针（甾醇型CSL和磷脂型16-PC）的动力学和结构特性的影响。我们的研究结果是一致的非理想的解决方案，含有胆固醇丰富的集群所创建的胆固醇在POPC模型膜的自关联。通过电子自旋共振（ESR）成像法，在15 ~ 60 ℃的温度范围内，在模型膜中的胆固醇的浓度为0 ~ 30摩尔%的范围内，测定自旋探针的横向扩散系数D。利用非线性最小二乘ESR谱模拟方法确定了旋转扩散系数（包括R垂直）和序参量S。CSL的D、R垂直和S与胆固醇摩尔百分比的线性关系有很大的偏离。当胆固醇浓度超过10 mol %时，CSL的D在15 ℃时降低4倍，在60 ℃时降低2倍，而16-PC的D几乎不受影响。胆固醇在30mol%胆固醇时使R垂直下降10倍，但16-PC略有增加。由于胆固醇的存在，观察到CSL的S显著增加。它示出了CSL与16-PC的组合物的S的变化的差异可以解释在其各自的活性系数方面，以及如何获得一个单一的通用的线性关系的S的两个探针在缩放的温度方面。还发现了D和R垂直于S的简单但一般的相关性，这有助于解释这些扩散系数。
The effects of cholesterol on the dynamics and the structural properties of two different spin probes, the sterol type CSL and the phospholipid type 16-PC, in POPC/cholesterol oriented multilayer model membranes were examined. Our results are consistent with a nonideal solution containing cholesterol-rich clusters created by the self association of cholesterol in POPC model membranes. The lateral diffusion coefficient D of the spin probes was measured over the temperature range of 15 to 60 degrees C and over the concentration range of 0 to 30 mol% of cholesterol in the model membrane by the electron spin resonance (ESR) imaging method. The rotational diffusion coefficients (including R perpendicular) and the order parameter S were determined utilizing a nonlinear least square ESR spectral simulation method. D, R perpendicular and S of CSL deviate considerably from linear dependence on mole percent cholesterol. The D of CSL was decreased by a factor of four at 15 degrees C and a factor of two at 60 degrees C for concentrations of cholesterol over 10 mol %, whereas those of 16-PC were hardly affected. Cholesterol decreased R perpendicular by a factor of 10 at 30 mol % of cholesterol, but it increased slightly that of 16-PC. A significant increase of S for CSL due to the presence of cholesterol was observed. It is shown how the difference in variation of S for CSL vs. 16-PC with composition may be interpreted in terms of their respective activity coefficients, and how a single universal linear relation is obtained for the S of both probes in terms of a scaled temperature. Simple but general correlations of D and of R perpendicular with S were also found, which aid in the interpretation of these diffusion coefficients.