Kleywegt G J, Jones T A
Department of Cell and Molecular Biology, Uppsala University, Biomedical Centre, Box 590, SE-751 24 Uppsala, Sweden.
Acta Crystallogr D Biol Crystallogr. 1999 Apr;55(Pt 4):941-4. doi: 10.1107/s0907444999001031.
Macromolecular phase-refinement and phase-extension calculations using real-space electron-density averaging techniques require accurate envelopes (or masks) to define the boundaries of each domain or molecule whose density is to be averaged. An extensive set of tools, implemented in four computer programs (O, MAMA, COMA and MASKIT) are described which can be used to generate such envelopes (either from an atomic model or based on local density-correlation maps), to improve them, to remove overlap owing to crystallographic or non-crystallographic symmetry, to display them and to manipulate them in a variety of manners.
使用实空间电子密度平均技术进行大分子相细化和相扩展计算需要精确的包络（或掩码）来定义每个密度要进行平均的结构域或分子的边界。本文描述了在四个计算机程序（O、MAMA、COMA和MASKIT）中实现的一系列广泛的工具，这些工具可用于生成此类包络（从原子模型或基于局部密度相关图）、改进它们、消除由于晶体学或非晶体学对称性导致的重叠、显示它们并以各种方式对其进行操作。
