UV Resonance Raman Characterization of a Substrate Bound to Human Indoleamine 2,3-Dioxygenase 1
UV Resonance Raman Characterization of a Substrate Bound to Human Indoleamine 2,3-Dioxygenase 1
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与人吲哚胺 2,3-双加氧酶 1 结合的底物的紫外共振拉曼表征
DOI：
10.1016/j.bpj.2019.07.017
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发表时间：
2019
影响因子：
3.4
通讯作者：
Takashi Ogura
中科院分区：
文献类型：
--
作者：
Sachiko Yanagisawa ; Kure’e Kayama ; Masayuki Hara ; Hiroshi Sugimoto ; Yoshitsugu Shiro ; Takashi Ogura
人吲哚胺2，3-双加氧酶1(IDO)是一种血红素酶，催化L-色氨酸(Trp)主要代谢途径的第一反应生成N-甲酰犬尿氨酸。该反应涉及色氨酸吲哚环上C2=C3键的断裂和两个原子氧从铁结合的O2插入到吲哚2和3位。为了建立这种独特的酶反应的化学机制，有必要确定与IDO结合的底物Trp的构象和电子状态。在本研究中，我们测量了IDO在色氨酸存在下的紫外共振拉曼光谱，以检测底物色氨酸的振动模式。我们比较了三元络合物(Trp结合氰化酶)和二元络合物(Trp结合还原酶)中Trp与游离Trp在溶液中的紫外共振拉曼光谱，发现与Trp的结合影响Trp的构象，导致两种络合物发生相似的变化，特别是在C3-Cβ键附近。然而，三元络合物中血红素第六配位上双原子配体的存在显著改变了色氨酸的迁移率和电子结构，很可能导致酶反应中C2=C3键的断裂。
Human indoleamine 2,3-dioxygenase 1 (IDO) is a heme enzyme that catalyzes the first reaction of the main metabolic pathway of L-tryptophan (Trp) to produce N-formylkynurenin. The reaction involves cleavage of the C2=C3bond in the Trp indole ring and insertion of two atomic oxygens from the iron-bound O2into the indole 2 and 3 position. For establishment of the chemical mechanism of this unique enzymatic reaction, it is necessary to determine the conformation and electronic state of the substrate Trp bound to IDO. In this study, we measured the ultraviolet resonance Raman spectra of IDO in the presence of Trp to detect the vibrational modes of the substrate Trp. We compared the ultraviolet resonace Raman spectra of Trp in a ternary complex (Trp-bound cyanide enzyme) and a binary complex (Trp-bound reduced enzyme) of IDO with that of free Trp in solution and found that binding to IDO influences the conformation of Trp, resulting in similar changes in the two complexes, especially around the C3-Cβbond. However, the presence of the diatomic ligand at the heme sixth coordination site in the ternary complex significantly alters the mobility and electronic structure of Trp, most likely resulting in the C2=C3bond cleavage in the enzymatic reaction.