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Characterization of the Distribution of Spin–Lattice Relaxation Rates of Lipid Spin Labels in Fiber Cell Plasma Membranes of Eye Lenses with a Stretched Exponential Function
Applied Magnetic Resonance ( IF 1 ) Pub Date : 2019-03-07 , DOI: 10.1007/s00723-019-01119-7
Natalia Stein 1 , Laxman Mainali 1 , James S Hyde 1 , Witold K Subczynski 1
Affiliation  

The stretched exponential function (SEF) was used to analyze and interpret saturation recovery (SR) electron paramagnetic resonance (EPR) data obtained from spin-labeled porcine eye-lens membranes. This function has two fitting parameters: the characteristic spin–lattice relaxation rate (T1str−1) and the stretching parameter (β), which ranges between zero and one. When β =1, the function is a single exponential. It is assumed that the SEF arises from a distribution of single exponential functions, each described by a T1 value. Because T1−1s are determined primarily by the rotational diffusion of spin labels, they are a measure of membrane fluidity. Since β describes the distribution of T1−1s, it can be interpreted as a measure of membrane heterogeneity. The SEF was used to analyze SR data obtained from intact cortical and nuclear fiber cell plasma membranes extracted from the eye lenses of 2-year-old animals and spin labeled with phospholipid and cholesterol analogs. The lipid environment sensed by these probe molecules was found to be less fluid and more heterogeneous in nuclear membranes than in cortical membranes. Parameters T1str−1 and β were also used for a multivariate K-means cluster analysis of stretched exponential data. This analysis indicates that SEF data can be assigned accurately to clusters in nuclear or cortical membranes. In future work, the SEF will be applied to analyze data from human eye lenses of donors with differing health histories.

中文翻译:

具有拉伸指数函数的镜片纤维细胞质膜中脂质自旋标记的自旋-晶格松弛率分布的表征

拉伸指数函数 (SEF) 用于分析和解释从自旋标记的猪眼晶状体膜获得的饱和恢复 (SR) 电子顺磁共振 (EPR) 数据。该函数有两个拟合参数:特征自旋-晶格弛豫率 (T1str−1) 和拉伸参数 (β),其范围在 0 和 1 之间。当 β =1 时,函数是单指数函数。假设 SEF 来自单个指数函数的分布,每个指数函数由 T1 值描述。由于 T1−1s 主要由自旋标记的旋转扩散决定,因此它们是膜流动性的量度。由于 β 描述了 T1−1s 的分布,因此可以将其解释为膜异质性的度量。SEF 用于分析从 2 岁动物的眼睛晶状体中提取的完整皮质和核纤维细胞质膜获得的 SR 数据,并用磷脂和胆固醇类似物标记。发现由这些探针分子感应的脂质环境在核膜中比在皮层膜中流动性更小且异质性更大。参数 T1str-1 和 β 也用于拉伸指数数据的多元 K 均值聚类分析。该分析表明,SEF 数据可以准确地分配给核膜或皮层膜中的簇。在未来的工作中,SEF 将用于分析来自具有不同健康史的捐赠者的人眼晶状体的数据。发现由这些探针分子感应的脂质环境在核膜中比在皮层膜中流动性更小且异质性更大。参数 T1str-1 和 β 也用于拉伸指数数据的多元 K 均值聚类分析。该分析表明,SEF 数据可以准确地分配给核膜或皮层膜中的簇。在未来的工作中,SEF 将用于分析来自具有不同健康史的捐赠者的人眼晶状体的数据。发现由这些探针分子感应的脂质环境在核膜中比在皮层膜中流动性更小且异质性更大。参数 T1str-1 和 β 也用于拉伸指数数据的多元 K 均值聚类分析。该分析表明,SEF 数据可以准确地分配给核膜或皮层膜中的簇。在未来的工作中,SEF 将用于分析来自具有不同健康史的捐赠者的人眼晶状体的数据。
更新日期:2019-03-07
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