Department of Biochemistry, Molecular Biology and Biophysics, Minneapolis, Minnesota 55455, USA.
Dalton Trans. 2013 Mar 7;42(9):3127-35. doi: 10.1039/c2dt32059b. Epub 2012 Oct 22.
Methylamine dehydrogenase (MADH) requires the cofactor tryptophan tryptophylquinone (TTQ) for activity. TTQ is a posttranslational modification that results from an 8-electron oxidation of two specific tryptophans in the MADH β-subunit. The final 6-electron oxidation is catalyzed by an unusual c-type di-heme enzyme, MauG. The di-ferric enzyme can react with H(2)O(2), but atypically for c-type hemes the di-ferrous enzyme can react with O(2) as well. In both cases, an unprecedented bis-Fe(IV) redox state is formed, composed of a ferryl heme (Fe(IV)=O) with the second heme as Fe(IV) stabilized by His-Tyr axial ligation. Bis-Fe(IV) MauG acts as a potent 2-electron oxidant. Catalysis is long-range and requires a hole hopping electron transfer mechanism. This review highlights the current knowledge and focus of research into this fascinating system.
甲胺脱氢酶（MADH）的活性需要辅因子色氨酸色基醌（TTQ）。TTQ 是一种翻译后修饰，它是 MADHβ 亚基中两个特定色氨酸的 8 电子氧化的结果。最后一个 6 电子氧化由一种不寻常的 c 型二血红素酶 MauG 催化。该双铁酶可以与 H（2）O（2）反应，但与 c 型血红素不同的是，双亚铁酶也可以与 O（2）反应。在这两种情况下，都会形成一种前所未有的双 Fe（IV）氧化还原态，由一个铁氧还蛋白血红素（Fe（IV）=O）和第二个血红素组成，第二个血红素由 His-Tyr 轴向配位稳定为 Fe（IV）。双 Fe（IV） MauG 作为一种有效的 2 电子氧化剂。催化是远程的，需要空穴跳跃电子转移机制。本综述重点介绍了当前对这个迷人系统的研究现状和重点。
