Ab initio phase determination for viruses with high symmetry: a feasibility study.
Ab initio phase determination for viruses with high symmetry: a feasibility study.
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高对称性病毒的从头相测定：可行性研究。
DOI：
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发表时间：
1992
期刊：
影响因子：
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通讯作者：
Michael G. Rossmann
中科院分区：
文献类型：
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作者：
Jun Tsao;Michael S. Chapman;Michael G. Rossmann
仅从初始球壳模型开始检查允许具有高内部对称性的球形病毒的完整结构测定的条件。审议了可能因以下原因而产生的问题。1.由于简单的壳模型及其在单位单元中的位置而产生中心相。中心对称性通常可以在基于观察到的结构振幅平均初始电子密度图时被打破，前提是内部分子对称性与晶体学对称性充分不平行。2.选择平均模型壳半径。一些不正确的半径导致巴比涅相反的解决方案（电子密度是负的，而不是积极的）。从具有不正确半径的其他模型导出的相位未能收敛到正确的解。3.结构振幅测量错误。4.缺乏完整的数据集。5.在晶体晶胞内定位初始球壳模型时出错。发现1.6A的误差在大于20A的分辨率下引起明显的相位误差。
Conditions that would permit the complete structure determination of spherical viruses that have high internal symmetry were examined starting only from an initial spherical shell model. Problems were considered that might arise due to the following. 1. Creation of centric phases due to the simple shell model and its position in the unit cell. The centric symmetry can generally be broken on averaging an initial electron density map based on observed structure amplitudes, provided that the internal molecular symmetry is sufficiently non-parallel to the crystallographic symmetry. 2. Choice of the average model shell radius. Some incorrect radii led to the Babinet opposite solution (electron density is negative instead of positive). Phases derived from other models with incorrect radii failed to converge to the correct solution. 3. Error in structure amplitude measurements. 4. Lack of a complete data set. 5. Error in positioning the initial spherical-shell model within the crystal unit cell. It was found that an error of 1.6 A caused noticeable phasing error at a resolution greater than 20 A.