Protein structural dynamics in solution unveiled via 100-ps time-resolved x-ray scattering
Protein structural dynamics in solution unveiled via 100-ps time-resolved x-ray scattering
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DOI：
10.1073/pnas.1002951107
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发表时间：
2010-04-20
影响因子：
11.1
通讯作者：
Anfinrud, Philip
中科院分区：
文献类型：
--
作者：
Cho, Hyun Sun;Dashdorj, Naranbaatar;Anfinrud, Philip
我们已经开发了一种时间分辨的X射线散射衍射仪，能够探测100 ps的时间分辨率的蛋白质在溶液中的结构动力学。该衍射仪是在先进光子源的ID 14 B BioCARS（先进辐射源联盟）光束线上开发的，可记录q范围为0.02-2.5埃（-1）的X射线散射快照，从而同时覆盖小角X射线散射（SAXS）和广角X射线散射（WAXS）区域。为了证明其能力，我们跟踪了肌红蛋白的结构变化，因为它经历了从一氧化碳形式（MbCO）到脱氧形式（Mb）的光解诱导转变。虽然MbCO和Mb晶体结构之间的差异很小（rmsd 22埃（3）），但蛋白质的体积膨胀。随后的构象松弛导致蛋白质在大约10 ns内收缩到比MbCO大大约2埃的体积。CO逃逸的时间尺度上的主要对接网站，另一个变化的SAXS/WAXS指纹出现，表现出敏感性的位置解离CO。全球分析的SAXS/WAXS模式恢复时间无关的散射指纹的Mb的四个中间状态。这些SAXS/WAXS指纹提供了严格的限制，推定模型的构象状态和它们之间的结构转换。
We have developed a time-resolved x-ray scattering diffractometer capable of probing structural dynamics of proteins in solution with 100-ps time resolution. This diffractometer, developed on the ID14B BioCARS (Consortium for Advanced Radiation Sources) beamline at the Advanced Photon Source, records x-ray scattering snapshots over a broad range of q spanning 0.02-2.5 angstrom(-1), thereby providing simultaneous coverage of the small-angle x-ray scattering (SAXS) and wide-angle x-ray scattering (WAXS) regions. To demonstrate its capabilities, we have tracked structural changes in myoglobin as it undergoes a photolysis-induced transition from its carbon monoxy form (MbCO) to its deoxy form (Mb). Though the differences between the MbCO and Mb crystal structures are small (rmsd 22 angstrom(3) volume expansion of the protein. The ensuing conformational relaxation causes the protein to contract to a volume similar to 2 angstrom(3) larger than MbCO within similar to 10 ns. On the timescale for CO escape from the primary docking site, another change in the SAXS/WAXS fingerprint appears, demonstrating sensitivity to the location of the dissociated CO. Global analysis of the SAXS/WAXS patterns recovered time-independent scattering fingerprints for four intermediate states of Mb. These SAXS/WAXS fingerprints provide stringent constraints for putative models of conformational states and structural transitions between them.