Schwartz S, Cain J E, Dratz E A, Blasie J K
Biophys J. 1975 Dec;15(12):1201-33. doi: 10.1016/S0006-3495(75)85895-4.
Oriented multilayers containing a membrane pair within the unit cell potentially possess both lattice disorder and substitution disorder. Lattice disorder occurs when there is a lack of long-range order in the lattice spacings produced by a variation in the nearest neighbor distances between unit cells. A simple form of substitution disorder can arise from a variation in the separation of the two membranes within the unit cells in the multilayer. Lattice disorder produces a monotonically increasing width for higher order lamellar "reflections" while simple substitution disorder produces an incoherent intensity underlying the coherent intensity. A generalized Patterson function analysis has been developed for treating lamellar diffraction from lattice disordered multilayers. This analysis allows the identification of the autocorrelation function of the unit cell electron density profile and its subsequent deconvolution to provide the unit cell electron density profile. A recursive procedure has been developed for separating the incoherent intensity from the coherent intensity via a Gaussian probability model of the membrane intra-pair separation. In cases studied so far both disorders can be quantitatively accounted for and eliminated from interfering with the phasing of the coherent intensity or distorting the derived electron density profile. Lamellar X-ray diffraction data from intact retinal rods, using either film or position sensitive detectors, shows severe effects of both forms of disorder which have not been taken into account in past analysis of such data. We have applied our analysis to the data on dark adapted rod outer segments in electrophysiologically intact retinas of Chabre and Cavaggioni (unpublished). An electron density profile is derived at 25 A resolution. The lattice nearest neighbor spacing has a variation of +/- 19 A out of a 295 A repeat. The intra-unit cell membrane pair center to center distance of 88 A varies +/-8 A.
在晶胞内包含膜对的定向多层膜可能同时具有晶格无序和取代无序。当晶胞间最近邻距离的变化导致晶格间距缺乏长程有序时，就会出现晶格无序。多层膜中晶胞内两层膜间距的变化会产生一种简单形式的取代无序。晶格无序会使高阶层状“反射”的宽度单调增加，而简单取代无序会在相干强度之下产生非相干强度。已经开发了一种广义帕特森函数分析方法来处理晶格无序多层膜的层状衍射。这种分析允许识别晶胞电子密度分布的自相关函数，并对其进行后续去卷积以提供晶胞电子密度分布。已经开发了一种递归程序，通过膜对内部分离的高斯概率模型将非相干强度与相干强度分离。在目前研究的案例中，两种无序都可以得到定量解释，并消除其对相干强度相位的干扰或对推导的电子密度分布的扭曲。使用胶片或位置敏感探测器从完整视网膜杆状细胞获得的层状X射线衍射数据显示，这两种无序形式都有严重影响，而过去对此类数据的分析并未考虑到这些影响。我们已将我们的分析应用于Chabre和Cavaggioni（未发表）电生理完整视网膜中暗适应杆状细胞外段的数据。以25埃的分辨率得出电子密度分布。在295埃的重复结构中，晶格最近邻间距的变化为±19埃。晶胞内膜对中心到中心的距离为88埃，变化±8埃。
