Elucidation of the catalytic mechanisms of the non-haem iron-dependent catechol dioxygenases: synthesis of carba-analogues for hydroperoxide reaction intermediates
作者:Christopher J. Winfield、Zeyana Al-Mahrizy、Michael Gravestock、Timothy D. H. Bugg
DOI:10.1039/b004265j
日期:——
The catalytic mechanisms of the non-haem iron-dependent intradiol and extradiol catechol dioxygenases are thought to involve transient hydroperoxide reaction intermediates, formed by reaction of a catechol substrate with dioxygen. The synthesis of carba-analogues of these intermediates is described in which the hydroperoxide functional group (–OOH) is replaced by a hydroxymethyl group (–CH2OH), and
非血红素依赖铁的内二醇和外二醇儿茶酚双加氧酶的催化机理被认为涉及瞬时的氢过氧化物反应中间体,该中间体是由邻苯二酚底物与双氧反应形成的。描述了这些中间体的碳水化合物类似物的合成,其中氢过氧化物官能团(–OOH)被羟甲基(–CH 2 OH)取代,并且环己二酮骨架简化为环己酮。发现“近端”氢过氧化物的类似物(其中羟甲基相对于环轴向定位)充当了多余的二醇酶2,3-二羟基苯基丙酸酯1,2-二加氧酶的竞争性抑制剂(K i 0.7–7.6 mM)。 (MhpB)来自大肠杆菌,而羟甲基位于赤道的类似物则没有抑制作用。相反,测定与来自假单胞菌属物种的内二醇裂解的原儿茶酸3,4-二加氧酶的比较。仅显示含有赤道羟甲基基团的类似物(IC 50 9.5 mM)具有抑制作用。这些数据支持在二醇外儿茶酚二加氧酶机制中存在近端氢过氧化物中间体,并表明氢过氧化物反应中间体采用的构象可能是决定二醇外和二醇内双加氧酶反应特异性的重要决定因素。