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首页> 外文期刊>Proceedings of the National Academy of Sciences of the United States of America >Allosteric action in real time: Time-resolved crystallographic studies of a cooperative dimeric hemoglobin
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Allosteric action in real time: Time-resolved crystallographic studies of a cooperative dimeric hemoglobin

机译：实时变构作用：合作二聚体血红蛋白的时间分辨晶体学研究

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摘要

Protein allostery provides mechanisms for regulation of biological function at the molecular level. We present here an investigation of global, ligand-induced allosteric transition in a protein by time-resolved x-ray diffraction. The study provides a view of structural changes in single crystals of Scapharca dimeric hemoglobin as they proceed in real time, from 5 ns to 80 mu s after ligand photodissociation. A tertiary intermediate structure forms rapidly (< 5 ns) as the protein responds to the presence of an unliganded heme within each R-state protein subunit, with key structural changes observed in the heme groups, neighboring residues, and interface water molecules. This intermediate lays a foundation for the concerted tertiary and quaternary structural changes that occur on a microsecond time scale and are associated with the transition to a low-affinity T-state structure. Reversal of these changes shows a considerable lag as a T-like structure persists well after ligand rebinding, suggesting a slow T-to-R transition.
机译：蛋白质变构提供了在分子水平上调节生物学功能的机制。我们在这里通过时间分辨的X射线衍射对蛋白质中全局，配体诱导的变构过渡进行研究。该研究提供了Scapharca二聚体血红蛋白单晶体在配体光解后5 ns至80 s实时进行的实时结构变化的观点。当蛋白质响应每个R状态蛋白质亚基中未配体血红素的存在时，三级中间结构迅速形成（<5 ns），在血红素基团，相邻残基和界面水分子中观察到关键的结构变化。该中间体为微秒级尺度上发生的，与过渡到低亲和力T态结构相关的三级和四级协同结构变化奠定了基础。这些变化的逆转显示出相当大的滞后，因为在配体重新结合后，T样结构仍然很好地存在，表明T到R的过渡很慢。

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