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首页> 外文期刊>Physical chemistry chemical physics: PCCP >Amide-imide tautomerization in the glutamine side chain in enzymatic and photochemical reactions in proteins
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Amide-imide tautomerization in the glutamine side chain in enzymatic and photochemical reactions in proteins

机译:在蛋白质中的酶促和光化学反应中谷氨酰胺侧链的酰胺 - 酰亚胺互变异物

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摘要

Amide-imide tautomerization presents a pervasive class of chemical transformations in organic chemistry of natural compounds. In this Perspective, we describe two distinctively different protein systems, in which the amide-imide tautomerization in the glutamine side chain takes place in enzymatic or photochemical reactions. First, hydrolysis of guanosine triphosphate (GTP) catalyzed by the Ras-GAP protein complex suggests the occurrence of the imide tautomer of glutamine in reaction intermediates. Second, photoexcitation of flavin-binding protein domains (BLUFs) initiates a chain of reactions in the chromophore-binding pocket, including amide-imide tautomerization of glutamine. Mechanisms of these reactions at the atomic level have been revealed in quantum mechanics/molecular mechanics (QM/MM) simulations. To reinforce conclusions on the critical role of amide-imide tautomerization of glutamine in these reactions we describe results of new quantum chemistry and QM/MM calculations for relevant molecular model systems. We reexamine results of the recent IR spectroscopy studies of BLUF domains, which provide experimental evidences of Gln tautomerization in proteins. We also propose to validate the glutamine-assisted mechanism of enzymatic GTP hydrolysis by using IR spectroscopy in a proper range of wavenumbers.
机译:Amide-Imide互变异化呈现出天然化合物的有机化学中的普遍化学转化。在这种观点中,我们描述了两个独特的不同蛋白质系统,其中谷氨酰胺侧链中的酰胺 - 酰亚胺互变异物发生在酶促或光化学反应中。首先,通过Ras-Gap蛋白复合物催化的鸟氨酸三磷酸(GTP)的水解表明谷氨酰胺的发生在反应中间体中的酰亚胺互变异构体。其次,Flavin结合蛋白质结构域(Blufs)的光筛引发了发色团结合口袋中的反应链,包括谷氨酰胺的酰胺 - 酰亚胺互变化。在量子力学/分子机制(QM / mm)模拟中揭示了原子水平的这些反应的机制。为了加强关于谷氨酰胺在这些反应中谷氨酰胺的关键作用的结论,我们描述了用于相关分子模型系统的新量子化学和QM / MM计算的结果。我们重新审查了BluF结构域近期IR光谱研究的结果,这为蛋白质中的Gln互变异化提供了实验证据。我们还提出通过在适当的波数范围内使用IR光谱来验证酶促GTP水解的谷氨酰胺辅助机制。

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