Williamson M P, Asakura T
Krebs Institute, Department of Molecular Biology and Biotechnology, University of Sheffield, UK.
FEBS Lett. 1992 May 11;302(2):185-8. doi: 10.1016/0014-5793(92)80436-k.
We have calculated chemical shifts for a range of diastereotopic protons in proteins (i.e. methylene protons, and the methyl groups of valine and leucine residues), using a recently optimised method for chemical shift calculation. The calculations are based on crystal structure coordinates, and have been compared with experimental stereospecific assignments. The results indicate that chemical shifts can be used to suggest stereospecific assignments with about 80% probability of being correct, in cases where both the experimental and the calculated chemical shift differences between a pair of diastereotopic protons are greater than 0.3 ppm. Inaccurate calculations are shown to be caused in most cases by differences between crystal and solution structures. Furthermore, chemical shift calculations based on NMR structures are shown to be capable of acting as a further constraint on structure, by limiting the range of side-chain conformations adopted in structures calculated from NMR data.
我们使用一种最近优化的化学位移计算方法，计算了蛋白质中一系列非对映异位质子（即亚甲基质子以及缬氨酸和亮氨酸残基的甲基）的化学位移。这些计算基于晶体结构坐标，并已与实验立体专一性归属进行了比较。结果表明，在一对非对映异位质子之间的实验和计算化学位移差异均大于0.3 ppm的情况下，化学位移可用于提示立体专一性归属，其正确概率约为80%。结果表明，不准确的计算在大多数情况下是由晶体结构和溶液结构之间的差异引起的。此外，基于NMR结构的化学位移计算表明，通过限制从NMR数据计算得到的结构中采用的侧链构象范围，能够对结构起到进一步的约束作用。
