Benisvy Laurent, Hammond Deborah, Parker David J, Davies E Stephen, Garner C David, McMaster Jonathan, Wilson Claire, Neese Frank, Bothe Eberhard, Bittl Robert, Teutloff Christian
Max-Planck-Instut für Bioanorganische Chemie, Stiftstrasse 34-46, Mülheim an der Ruhr, D45470, Germany.
J Inorg Biochem. 2007 Nov;101(11-12):1859-64. doi: 10.1016/j.jinorgbio.2007.07.013. Epub 2007 Jul 21.
The synthesis and structure of an o-methylthio-phenol-imidazole, 2-(2'-(4'-tert-butyl-6'-methylsulfanyl)-hydroxyphenyl))-4,5-diphenyl-imidazole ((MeS)LH), is reported; X-ray crystallographic studies have shown that (MeS)LH involves an O-H...N(+) hydrogen bond between the phenol and an imidazole nitrogen. (MeS)LH undergoes a reversible, one-electron, oxidation to form the radical cation (MeS)LH(+) the EPR spectrum of which is remarkably similar to that of ()Tyr(272) in Cu-free, oxidized, apo-GO. Density Functional Theory calculations, have shown that the proton-transferred (R-O()...H-N(+)) form of (MeS)LH(+) has a spin density distribution--with a substantial delocalization of the unpaired electron spin density onto the ortho sulfur atom--and EPR properties that are in good agreement with those of ()Tyr(272) in Cu-free, oxidized, apo-GO whereas the non-proton-transferred (R-O()(+)-H...N) form does not. The results reported herein are a further demonstration of the influence of hydrogen bonding on the nature and properties of phenoxyl radicals and strongly suggest that the phenoxyl oxygen of ()Tyr(272) in Cu-free, oxidized, apo-GO is involved in a O()...H-O/N hydrogen bond.
报道了邻甲硫基苯酚 - 咪唑2-(2'-(4'-叔丁基 - 6'-甲硫基) - 羟基苯基)) - 4,5 - 二苯基 - 咪唑((MeS)LH)的合成与结构；X射线晶体学研究表明，(MeS)LH在苯酚和咪唑氮之间存在O - H...N(+)氢键。(MeS)LH经历可逆的单电子氧化形成自由基阳离子(MeS)LH(+)，其电子顺磁共振光谱与无铜、氧化的脱辅基葡萄糖氧化酶中()Tyr(272)的光谱非常相似。密度泛函理论计算表明，(MeS)LH(+)的质子转移形式(R - O()...H - N(+))具有自旋密度分布——未成对电子自旋密度大量离域到邻位硫原子上——以及与无铜、氧化的脱辅基葡萄糖氧化酶中()Tyr(272)的电子顺磁共振性质高度一致，而非质子转移形式(R - O()(+)-H...N)则不然。本文报道的结果进一步证明了氢键对苯氧基自由基性质和特性的影响，并强烈表明无铜、氧化的脱辅基葡萄糖氧化酶中()Tyr(272)的苯氧基氧参与了O()...H - O/N氢键。
