Models for slow anisotropic rotational diffusion in saturation transfer electron paramagnetic resonance at 9 and 35 GHz.
Models for slow anisotropic rotational diffusion in saturation transfer electron paramagnetic resonance at 9 and 35 GHz.
复制标题
9 和 35 GHz 饱和传输电子顺磁共振中缓慢各向异性旋转扩散的模型。
DOI：
10.1021/bi00261a041
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发表时间：
1982
期刊：
影响因子：
2.9
通讯作者：
Fung,LW
中科院分区：
文献类型：
--
作者：
Johnson,ME;Lee,L;Fung,LW
迈克尔·e·约翰逊，*拉娜·李，莱斯利·w·m。模型系统的胆甾烷和5-羟基硬脂酸模拟自旋探针在脂双层分散的双棕榈酰磷脂酰胆碱和胆固醇（9∶1 w/w）被用来分析饱和转移电子顺磁共振频谱行为的缓慢旋转扩散在各向异性介质。测量在9 GHz和35 GHz进行，为不同类型的运动提供增强的频谱分辨率。饱和转移光谱不同区域的光谱参数的参数相关图似乎对表征不同类型的运动具有潜在的作用。沿与氮氧化物y轴一致的对称轴的各向异性旋转扩散与沿氮氧化物z轴的各向异性旋转扩散有明显区别，也可与沿氮氧化物z轴的各向异性旋转扩散区分开来。在某些条件下，近似各向异性旋转扩散在与氮氧化物z主轴一致的对称轴上与各向同性旋转扩散是有区别的。近年来，自旋标记快速通过饱和转移电子顺磁共振（ST-EPR） 1方法在各种膜系统研究中的应用有了显著的增长。最近的应用程序包括使用多个自旋探针研究烃地区内的动态行为模型(Delmelle et al ., 1980;沼泽,1980;Marsh &瓦,1980;瓦和沼泽,1981)和红细胞(斯威夫特et al ., 1980; Fung, 1981)膜,研究视觉的视紫红质膜受体(Kusumi et al ., 1978年,1980;巴鲁安et al ., 1979; Favre et al ., 1979; Davoust et al ., 1980),肌质网状atp酶的研究(Kirino et al ., 1978;伊达尔戈et al ., 1978;Thomas & Hidalgo, 1978)，红细胞膜光谱-膜相互作用的研究（Fung et al., 1979; Lemaigre-Dubreuil et al., 1980; Fung, 1981），以及重组细胞色素c氧化酶的研究（Swanson et al., 1980）。在最近的评论中讨论了这些和其他一些应用（Hyde, 1978; Hyde & Dalton, 1979; Hyde & Thomas, 1980）。在许多这些应用中，ST-EPR光谱行为表明各向异性运动的存在，但由于缺乏对各向异性运动对ST-EPR光谱行为影响的详细了解，对这种运动的分析相当有限。各向异性旋转扩散可以由两种不同的物理机制引起：(a)在各向同性介质中进行旋转扩散的高度不对称分子和(b)在具有定向恢复潜力的各向异性介质中进行旋转扩散的任意形状的分子。根据溶质和溶剂分子的相对大小，这些主要的扩散机制也可以进一步细分为扩散过程。这些细分包括大分子在低分子量溶剂中的布朗重定向和小分子的强跳跃重定向
Michael E. Johnson,* Lana Lee, and Leslie W.-M. Fung* abstract: Model systems of cholestane and 5-doxylstearic acid analogue spin probes in lipid bilayer dispersions of dipalmitoylphosphatidylcholine and cholesterol (9: 1 w/w) are used to analyzesaturation transfer electron paramagnetic resonance spectral behavior for slow rotational diffusion in an anisotropic medium. Measurements are made at both 9 and 35 GHz to provide enhanced spectral resolution for different types of motion. Parameter correlation plots of spectral pa-rameters from different regions of the saturation transfer spectra appear to be potentially useful in characterizing dif-ferent types of motion. Anisotropic rotational diffusion about a symmetry axis coincident with the nitroxide y principal axis is clearly distinguishable from isotropic rotational diffusion and may be distinguishable from rotational diffusion about the nitroxide z principal axis. Approximate anisotropic ro-tational diffusion about a symmetry axis coincident with the nitroxide z principal axis is distinguishable from isotropic rotational diffusion under some, but not all, conditions. e application of spin-label rapid passage saturation transfer electron paramagnetic resonance(ST-EPR) 1 methods to the study of various membrane systems has shown a substantial increase over the last few years. Recent applications include the use of several spin probes to study motional behavior within the hydrocarbon region of model (Delmelle et al., 1980; Marsh, 1980; Marsh & Watts, 1980; Watts & Marsh, 1981) and erythrocyte (Swift et al., 1980; Fung, 1981) membranes, studies of rhodopsin in the visual receptor membrane (Kusumi et al., 1978, 1980; Baroin et al., 1979; Favre et al., 1979; Davoust et al., 1980), studies of the sarcoplasmic reticular ATPase (Kirino et al., 1978; Hidalgo et al., 1978; Thomas & Hidalgo, 1978), studies of the spectrin-membrane interaction in erythrocyte membranes (Fung et al., 1979; Lemaigre-Dubreuil et al., 1980; Fung, 1981), and studies of reconstituted cytochrome c oxidase (Swanson et al., 1980). Several of these and other applications are discussed in recent reviews (Hyde, 1978; Hyde & Dalton, 1979; Hyde & Thomas, 1980). For many of these applications the ST-EPR spectral be-havior suggests the existence of anisotropic motion, but analysis of such motion has been quite limited due to the lack of a detailed understanding of the effects of anisotropic motion upon ST-EPR spectral behavior. Anisotropic rotational dif-fusion can result from two different physical mechanisms:(a) a highly asymmetric molecule undergoing rotational diffusion in an isotropic medium and (b) a molecule (of arbitrary shape) undergoing rotational diffusion in an anisotropic medium which exhibits an orientational restoring potential. Each of these major diffusional mechanisms can also be further subdivided into diffusional processes depending on the relative sizes of solute and solvent molecules. These subdivisions include Brownian reorientation of a large molecule in a low molecular weight solvent, strong jump reorientation of a small molecule