Terwilliger Thomas C
Los Alamos National Laboratory, Los Alamos, NM 87545, USA.
Acta Crystallogr D Biol Crystallogr. 2010 Mar;66(Pt 3):276-84. doi: 10.1107/S0907444910000302. Epub 2010 Feb 12.
A method for rapidly building beta-sheets into electron-density maps is presented. beta-Strands are identified as tubes of high density adjacent to and nearly parallel to other tubes of density. The alignment and direction of each strand are identified from the pattern of high density corresponding to carbonyl and C(beta) atoms along the strand averaged over all repeats present in the strand. The beta-strands obtained are then assembled into a single atomic model of the beta-sheet regions. The method was tested on a set of 42 experimental electron-density maps at resolutions ranging from 1.5 to 3.8 A. The beta-sheet regions were nearly completely built in all but two cases, the exceptions being one structure at 2.5 A resolution in which a third of the residues in beta-sheets were built and a structure at 3.8 A in which under 10% were built. The overall average r.m.s.d. of main-chain atoms in the residues built using this method compared with refined models of the structures was 1.5 A.
本文提出了一种将β折叠快速构建到电子密度图中的方法。β链被识别为与其他密度管相邻且几乎平行的高密度管。每条链的排列和方向是根据沿着链上所有重复单元平均后的羰基和C(β)原子对应的高密度模式来确定的。然后将得到的β链组装成β折叠区域的单个原子模型。该方法在一组分辨率范围为1.5至3.8 Å的42个实验电子密度图上进行了测试。除了两个案例外，β折叠区域几乎全部构建完成，这两个例外情况分别是一个分辨率为2.5 Å的结构，其中β折叠中三分之一的残基被构建，以及一个分辨率为3.8 Å的结构，其中构建的残基不到10%。使用该方法构建的残基中主链原子与结构的精修模型相比，总体平均均方根偏差为1.5 Å。
