Metalloprotein Crystallography: More than a Structure.
Metalloprotein Crystallography: More than a Structure.
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金属蛋白晶体学：不仅仅是结构。
DOI：
10.1021/acs.accounts.5b00538
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发表时间：
2016-04-19
影响因子：
18.3
通讯作者：
Drennan CL
中科院分区：
文献类型：
--
作者：
Bowman SE;Bridwell-Rabb J;Drennan CL
金属离子和金属辅因子在广泛的生物化学反应中起着重要的作用。因此，据估计，多达25-50%的蛋白质组使用过渡金属离子来执行各种基本功能。金属蛋白中的金属离子根据化学性质发挥功能作用，其多样性是由于过渡金属可以采用不同的氧化还原状态和几何形状，这取决于金属的身份和蛋白质环境。金属离子与金属辅因子（如血红素和钴胺素）中的有机框架的偶联进一步扩展了金属在生物学中的化学功能。蛋白质支架内金属离子和复杂金属辅因子的三维可视化通常是酶学的起点，突出了金属蛋白结构表征的重要性。然而，金属蛋白晶体学提出了许多隐含的挑战，包括正确地掺入相关的金属或金属辅因子，保持蛋白质纯化和结晶的适当环境（包括提供厌氧，寒冷或无光环境），并注意X射线诱导的蛋白质或掺入的金属离子损伤的可能性。然而，掺入的金属或金属辅因子在金属蛋白晶体学中也呈现出独特的优势。金属在用于蛋白质晶体学的波长下与X射线光子发生的显着共振以及金属丰富的电子特性，这些特性提供了强烈的和光谱学上独特的特征，允许金属蛋白质晶体学家使用异常色散来确定结构溶液的相，并在单晶上使用同时或并行的光谱技术。这些特性，再加上光束亮度的提高、X射线束波长的调节能力、先进探测器的可用性以及在许多同步加速器光束线上结合光谱设备，在金属蛋白质方面取得了令人兴奋的发展结构确定。在这里，我们将介绍金属在金属蛋白晶体学中的有利用途的结果，包括使用金属辅因子来获得相位信息，使用K边X射线吸收光谱来识别金属蛋白晶体中的金属配位，以及使用晶体上的紫外-可见光谱来探测结晶蛋白的酶活性。
Metal ions and metallocofactors play important roles in a broad range of biochemical reactions. Accordingly, it has been estimated that as much as 25–50% of the proteome uses transition metal ions to carry out a variety of essential functions. The metal ions incorporated within metalloproteins fulfill functional roles based on chemical properties, the diversity of which arises as transition metals can adopt different redox states and geometries, dictated by the identity of the metal and the protein environment. The coupling of a metal ion with an organic framework in metallocofactors, such as heme and cobalamin, further expands the chemical functionality of metals in biology. The three-dimensional visualization of metal ions and complex metallocofactors within a protein scaffold is often a starting point for enzymology, highlighting the importance of structural characterization of metalloproteins. Metalloprotein crystallography, however, presents a number of implicit challenges including correctly incorporating the relevant metal or metallocofactor, maintaining the proper environment for the protein to be purified and crystallized (including providing anaerobic, cold, or aphotic environments), and being mindful of the possibility of X-ray induced damage to the proteins or incorporated metal ions. Nevertheless, the incorporated metals or metallocofactors also present unique advantages in metalloprotein crystallography. The significant resonance that metals undergo with X-ray photons at wavelengths used for protein crystallography and the rich electronic properties of metals, which provide intense and spectroscopically unique signatures, allow a metalloprotein crystallographer to use anomalous dispersion to determine phases for structure solution and to use simultaneous or parallel spectroscopic techniques on single crystals. These properties, coupled with the improved brightness of beamlines, the ability to tune the wavelength of the X-ray beam, the availability of advanced detectors, and the incorporation of spectroscopic equipment at a number of synchrotron beamlines, have yielded exciting developments in metalloprotein structure determination. Here we will present results on the advantageous uses of metals in metalloprotein crystallography, including using metallocofactors to obtain phasing information, using K-edge X-ray absorption spectroscopy to identify metals coordinated in metalloprotein crystals, and using UV–vis spectroscopy on crystals to probe the enzymatic activity of the crystallized protein.