Rigby Stephen E J, Hynson Robert M G, Ramsay Rona R, Munro Andrew W, Scrutton Nigel S
Department of Biological Sciences, Queen Mary College, University of London, London E1 4NS, United Kingdom.
J Biol Chem. 2005 Feb 11;280(6):4627-31. doi: 10.1074/jbc.M410596200. Epub 2004 Nov 18.
We present spectroscopic evidence consistent with the presence of a stable tyrosyl radical in partially reduced human monoamine oxidase (MAO) A. The radical forms following single electron donation to MAO A and exists in equilibrium with the FAD flavosemiquinone. Oxidative formation of the tyrosyl radical in MAO is not reliant on neighboring metal centers and uniquely requires reduction of the active site flavin to facilitate oxidation of a tyrosyl side chain. The identified tyrosyl radical provides the key missing link in support of the single electron transfer mechanism for amine oxidation by MAO enzymes.
我们提供了光谱学证据,证明在部分还原的人单胺氧化酶(MAO)A中存在稳定的酪氨酸自由基。该自由基在向MAO A单电子供体后形成,并与FAD半醌黄素处于平衡状态。MAO中酪氨酸自由基的氧化形成不依赖于相邻的金属中心,且唯一需要的是活性位点黄素的还原,以促进酪氨酸侧链的氧化。所鉴定的酪氨酸自由基为支持MAO酶氧化胺的单电子转移机制提供了关键的缺失环节。