Minireview: A Comeback of Hg‐Derivatives in Protein Crystallography with Cys‐Modification
Minireview: A Comeback of Hg‐Derivatives in Protein Crystallography with Cys‐Modification
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DOI：
10.1002/cben.201400029
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发表时间：
2015-04
期刊：
影响因子：
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通讯作者：
H. Chan;T. Ko;Chun-Hsiang Huang;R. Guo
中科院分区：
文献类型：
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作者：
H. Chan;T. Ko;Chun-Hsiang Huang;R. Guo
虽然大多数蛋白质的晶体结构是通过分子置换(MR)来解决的，但它受到现有同源模型的限制，这些模型具有足够的序列一致性。另一种流行的方法是多波长反常衍射(MAD)，它使用Se-Met和同步辐射。然而，含有Se-Met的蛋白质有时很难获得和/或结晶。因此，其他重原子衍生物仍被用于晶体结构的测定，而单同晶置换(SIR)和单波长反常衍射(SAD)比传统的多重同晶置换(MIR)更受欢迎。这里讨论了最近的一些以汞作为唯一重原子类型的结构测定的例子。对于汞衍生物，数据收集不需要吸收光谱扫描，可以使用内部X射线源进行。汞的衍生化可以直接开始，方法是将天然晶体浸泡在含汞的溶液中，或者在酶的活性部位使用特定的突变体，如果酶缺乏固有的游离半胱氨酸残基。生物信息学和蛋白质工程的快速发展使这种依赖半胱氨酸的MIR、SIR和SAD汞相变策略成为除MR和MAD之外的一种有效的晶体结构测定方法。
While a majority of protein crystal structures are solved by using molecular replacement (MR), it is limited by the available homologous models with sufficient sequence identity. Another popular method is multi-wavelength anomalous diffraction (MAD) that uses Se-Met and synchrotron radiations. However, proteins containing Se-Met are sometimes difficult to obtain and/or crystallize. Consequently, other heavy-atom derivatives are still used in crystal structure determination, while single isomorphous replacement (SIR) and single wavelength anomalous diffraction (SAD) are more popular than conventional multiple isomorphous replacement (MIR). Here, some recent cases of structure determination in which Hg serves as the only heavy-atom type are discussed. For Hg-derivatives, data collection does not need absorption spectrum scanning and it can be carried out using an in-house X-ray source. Derivatization with Hg can start directly by soaking the native crystals in Hg-containing solutions, or use a specific mutant in the active site of an enzyme if it lacks intrinsic free cysteine residues. The rapid advance of bioinformatics and protein engineering has made this strategy of cysteine-dependent Hg-phasing by MIR, SIR and SAD an effective method of choice besides MR and MAD for crystal structure determination.