Gilmore C J, Nicholson W V, Dorset D L
Department of Chemistry, University of Glasgow, Scotland.
Acta Crystallogr A. 1996 Nov 1;52 ( Pt 6):937-46. doi: 10.1107/s0108767396008744.
Using maximum entropy and likelihood, an ab initio phase determination was carried out in projection at ca 6-10 A resolution for two dissimilar membrane proteins: the Omp F porin from the outer membrane of E. coli (largely beta-sheet) and halorhodopsin (largely alpha-helix). Accurate phase information found for the most likely solutions enabled potential maps to be calculated that contained most of the essential structural details of these macromolecules without the need for any image-derived phases as a starting set for phase extension or the necessity to use envelopes or electron-density histograms. A comparison with earlier calculations using the Sayre-Hughes equation coupled with phase annealing and the Luzzati flatness criterion used as a figure of merit is made.
利用最大熵和似然性，对两种不同的膜蛋白在约6 - 10埃分辨率下进行了投影中的从头相位测定：大肠杆菌外膜的OmpF孔蛋白（主要为β折叠）和嗜盐视紫红质（主要为α螺旋）。为最可能的解决方案找到的准确相位信息使得能够计算出包含这些大分子大部分基本结构细节的势能图，而无需任何源自图像的相位作为相位扩展的起始集，也无需使用包络或电子密度直方图。还与早期使用塞尔-休斯方程结合相位退火以及将卢扎蒂平坦度准则用作品质因数的计算进行了比较。
