Atomic resolution structures of trypsin provide insight into structural radiation damage
Atomic resolution structures of trypsin provide insight into structural radiation damage
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DOI：
10.1107/s0907444901000646
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发表时间：
2001-04-01
影响因子：
2.2
通讯作者：
Smalås, AO
中科院分区：
文献类型：
--
作者：
Leiros, HKS;McSweeney, SM;Smalås, AO
辐射损伤是蛋白质X射线结晶学中固有的问题，最近研究表明，辐射损伤过程具有高度的特异性，表现出二硫键断裂、酸性残基脱羧基、原子B因子增加和单位细胞体积增大等特征。本文报道了两种原子分辨率(1.00埃和0.95埃)的胰酶结构，它们的数据是在第三代同步加速器(ESRF)上用两条不同的光束线收集的。这两种胰酶结构都显示出断裂的二硫键；特别是从Cys191到Cys220的键对同步辐射非常敏感。在最强光束线(ID14-EH4)收集的数据集显示，结构辐射损伤增加，半胱氨酸残基的占有率降低，六个二硫键断裂更多，交替构象更多。可见，高强度的X射线不仅对蛋白质晶体的伤害最大，而且对蛋白质晶体的伤害也最大。
Radiation damage is an inherent problem in protein X-ray crystallography and the process has recently been shown to be highly specific, exhibiting features such as cleavage of disulfide bonds, decarboxylation of acidic residues, increase in atomic B factors and increase in unit-cell volume. Reported here are two trypsin structures at atomic resolution (1.00 and 0.95 Angstrom), the data for which were collected at a third-generation synchrotron (ESRF) at two different beamlines. Both trypsin structures exhibit broken disulfide bonds; in particular, the bond from Cys191 to Cys220 is very sensitive to synchrotron radiation. The data set collected at the most intense beamline (ID14-EH4) shows increased structural radiation damage in terms of lower occupancies for cysteine residues, more breakage in the six disulfide bonds and more alternate conformations. It appears that high intensity and not only the total X-ray dose is most harmful to protein crystals.