Direct observation of fast protein conformational switching
Direct observation of fast protein conformational switching
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DOI：
10.1073/pnas.0803764105
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发表时间：
2008-06-24
影响因子：
11.1
通讯作者：
Fayer, Michael D.
中科院分区：
文献类型：
--
作者：
Ishikawa, Haruto;Kwak, Kyungwon;Fayer, Michael D.
折叠蛋白质可以以多种构象亚态存在。每个子状态反映了一个局部最小的自由能景观与不同的结构。通过使用超快2D-IR振动回波化学交换光谱，观察到的肌红蛋白突变体的两个定义良好的亚态之间的构象切换约为50 ps的时间尺度。构象动力学的直接测量通过在二维红外光谱中的交叉峰的生长结合到血红素活性位点的CO。构象转换涉及改变组氨酸咪唑侧基位置的远端组氨酸/E螺旋的运动。子态之间的交换改变了CO的频率，这是由2D-IR振动回波光谱的时间依赖性检测。这些结果表明，蛋白质构象亚状态之间的相互转换可以发生在非常快的时间尺度。更大的结构变化，发生在更长的时间尺度上的影响进行了讨论。
Folded proteins can exist in multiple conformational substates. Each substate reflects a local minimum on the free-energy landscape with a distinct structure. By using ultrafast 2D-IR vibrational echo chemical-exchange spectroscopy, conformational switching between two well defined substates of a myoglobin mutant is observed on the approximate to 50-ps time scale. The conformational dynamics are directly measured through the growth of cross peaks in the 2D-IR spectra of CO bound to the heme active site. The conformational switching involves motion of the distal histidine/E helix that changes the location of the imidazole side group of the histidine. The exchange between substates changes the frequency of the CO, which is detected by the time dependence of the 2D-IR vibrational echo spectrum. These results demonstrate that interconversion between protein conformational substates can occur on very fast time scales. The implications for larger structural changes that occur on much longer time scales are discussed.