Prosser R Scott, Evanics Ferenc, Kitevski Julianne L, Patel Sagar
Department of Chemistry, University of Toronto, UTM, 3359 Mississauga Rd. North, Mississauga, ON, Canada L5L 1C6.
Biochim Biophys Acta. 2007 Dec;1768(12):3044-51. doi: 10.1016/j.bbamem.2007.09.011. Epub 2007 Oct 16.
An important component of the study of membrane proteins involves the determination of details associated with protein topology - for example, the location of transmembrane residues, specifics of immersion depth, orientation of the protein in the membrane, and extent of solvent exposure for each residue. Solution state NMR is well suited to the determination of immersion depth with the use of paramagnetic additives designed to give rise to depth-specific relaxation effects or chemical shift perturbations. Such additives include spin labels designed to be "anchored" within a given region of the membrane or small freely diffusing paramagnetic species, whose partitioning properties across the water membrane interface create a gradient of paramagnetic effects which correlate with depth. This review highlights the use of oxygen and other small paramagnetic additives in studies of immersion depth and topology of membrane proteins in lipid bilayers and micelles.
膜蛋白研究的一个重要组成部分涉及确定与蛋白质拓扑结构相关的细节，例如跨膜残基的位置、沉浸深度的具体情况、蛋白质在膜中的方向以及每个残基的溶剂暴露程度。溶液状态核磁共振非常适合通过使用旨在产生深度特异性弛豫效应或化学位移扰动的顺磁性添加剂来确定沉浸深度。此类添加剂包括设计为“锚定”在膜的给定区域内的自旋标记或小的自由扩散顺磁性物质，其在水-膜界面的分配特性会产生与深度相关的顺磁性效应梯度。本综述重点介绍了氧和其他小顺磁性添加剂在脂质双层和胶束中膜蛋白沉浸深度和拓扑结构研究中的应用。
