Low-barrier hydrogen bond in photoactive yellow protein
Low-barrier hydrogen bond in photoactive yellow protein
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DOI：
10.1073/pnas.0811882106
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发表时间：
2009-01
期刊：
影响因子：
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通讯作者：
S. Yamaguchi;H. Kamikubo;K. Kurihara;R. Kuroki;N. Niimura;N. Shimizu;Y. Yamazaki;M. Kataoka
中科院分区：
文献类型：
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作者：
S. Yamaguchi;H. Kamikubo;K. Kurihara;R. Kuroki;N. Niimura;N. Shimizu;Y. Yamazaki;M. Kataoka
低能垒氢键(LBHBs)被认为在蛋白质功能中发挥作用，包括酶催化和质子转移。LBHBs的瞬时形成有望稳定特定的反应中间产物。然而，基于实验结果和理论考虑，反对LBHB在蛋白质中的重要性的论点已经提出。这种差异是由于没有直接确定氢原子的位置造成的。在这里，我们用光活性黄色蛋白(PYP)的高分辨中子结晶学证明，即使在基态下，蛋白质中也存在LBHB。我们鉴定了PYP中87%(819/942)的氢位，并证明了发色团与E46之间的氢键是≈。这种LBHB稳定了隐藏在蛋白质内部疏水环境中的孤立电荷。我们认为，在激发态下，LBHB到正常氢键的快速弛豫是光信号传播到蛋白质部分的触发。这些结果为深入研究LBHBs的新作用和LBHb的形成机制提供了新的思路。
Low-barrier hydrogen bonds (LBHBs) have been proposed to play roles in protein functions, including enzymatic catalysis and proton transfer. Transient formation of LBHBs is expected to stabilize specific reaction intermediates. However, based on experimental results and theoretical considerations, arguments against the importance of LBHB in proteins have been raised. The discrepancy is caused by the absence of direct identification of the hydrogen atom position. Here, we show by high-resolution neutron crystallography of photoactive yellow protein (PYP) that a LBHB exists in a protein, even in the ground state. We identified ≈87% (819/942) of the hydrogen positions in PYP and demonstrated that the hydrogen bond between the chromophore and E46 is a LBHB. This LBHB stabilizes an isolated electric charge buried in the hydrophobic environment of the protein interior. We propose that in the excited state the fast relaxation of the LBHB into a normal hydrogen bond is the trigger for photo-signal propagation to the protein moiety. These results give insights into the novel roles of LBHBs and the mechanism of the formation of LBHBs.