SAD manganese in two crystal forms of glucose isomerase.
SAD manganese in two crystal forms of glucose isomerase.
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葡萄糖异构酶的两种晶体形式的 SAD 锰。
DOI：
10.1107/s0907444903005663
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发表时间：
2003
期刊：
影响因子：
--
通讯作者：
Dauter,Zbigniew
中科院分区：
文献类型：
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作者：
Ramagopal,UdupiA;Dauter,Miroslawa;Dauter,Zbigniew
来自红红链霉菌的葡萄糖异构酶以两种形式结晶：I222，在不对称单元中具有一个 44 kDa 的分子，以及 P21212，具有两个独特的分子。 I222结构是已知的，但P21212形式以前尚未解决。 P21212 形式的 X 射线衍射数据在 1.54 Å 波长处收集，I222 形式的 X 射线衍射数据在三个不同波长处收集：1.34、1.07 和 0.98 Å。这些数据集中 1 个 Mn 原子和 8 个 S 原子的异常信号量从 1.24% 到低至 0.56% 不等。双空间直接方法程序 SHELXD 针对 Bijvoet 差异运行，给出了所有数据集的所有异常散射体的清晰解。仅 Mn 位置用于所有四个数据集的 SAD 定相。密度修改后的电子密度图是由单波长数据集的定相产生的，并且纯粹基于异常 δf'' 的贡献，可以清楚地解释；在所有四种情况下，在没有人工干预的情况下，warp 建立了几乎完整的蛋白质模型。据了解，这是首次成功利用低至0.6%的异常信号来确定大分子的结构。
Glucose isomerase from Streptomyces rubiginosus was crystallized in two forms: I222, with one molecule of 44 kDa in the asymmetric unit, and P21212, with two unique molecules. The I222 structure is known, but the P21212 form has not been solved before. X-ray diffraction data for the P21212 form were collected at a wavelength of 1.54 Å and data for the I222 form were collected at three different wavelengths: 1.34, 1.07 and 0.98 Å. The amount of anomalous signal from one Mn and eight S atoms in these data sets varies from 1.24% to as low as 0.56%. The dual-space direct-methods program SHELXD, run against the Bijvoet differences, gave a clear solution of all anomalous scatterers for all data sets. The Mn positions only were used for SAD phasing of all four data sets. The electron-density map after density modification, resulting from the phasing of a single-wavelength data set and based purely on the anomalous δf'' contribution, was clearly interpretable; an almost complete model of the protein was built by wARP without human intervention in all four cases. As far as is known, this is the first time that an anomalous signal as low as 0.6% has successfully been used to determine the structure of a macromolecule.