MODEL STUDIES OF HYDROPORPHYRIN-CONTAINING ENZYMES

本研究的目的是阐明其结构和机制。 含氢卟啉的酶的详细信息。利息主要集中在 亚硝酸盐和亚硫酸盐还原酶是两类相关的酶，它们携带 它们的底物发生了不寻常的六电子还原。这些酶 最低限度地含有铁-异细菌碘氯复合体，以及一种 铁氧还蛋白样Fe4S4为修复基。合成类似物 这些假体基团的(模型)将通过化学手段制备。 这些类似物的结构、性质和反应性将 进行调查以了解其功能和环境 酶中的假体基团。迄今未知的复合体 将制备含有连接到Fe4S4中心的血红素基团的化合物。这个 活性中心已经被提出具有这种类型的结构。 对类似物的调查将提供证据来确定 这种结构类型存在于酶中，将有助于识别 并对其性质和功能进行了阐述。 关于西罗血红素类似物的结构和反应性的方面将是 与其他亚麻族进行比较。差异可能会暗示 酶的重要机制特征。亚硝酸盐的相互作用 和亚硫酸盐，含西铁血红素类似物，然后还原为产物 将会被调查。

The goal of this research is to elucidate the structural and mechanistic details of hydroporphyrin containing enzymes. Interest is centered upon nitrite and sulfite reductases, two related classes of enzymes which carry out the unusual six-electron reductions of their substrates. These enzymes minimally contain siroheme, an iron-isobacteriochlorin complex, and a ferredoxin-like Fe4S4 center as prosthetic groups. Synthetic analogues (models) of these prosthetic groups will be prepared by chemical means. The structure, properties, and reactivity of these analogues will investigated in order to gain insight to the function and environment of the prosthetic groups in the enzymes. The as yet unknown complexes containing a heme group linked to an Fe4S4 center will be prepared. The active sites have been proposed to have this type of structure. Investigation of the analogues will provide evidence to determine whether this structure type is present in the enzymes, will aid in identification of the mode of linkage, and will elucidate its properties and functions. Aspects of the structure and reactivity of siroheme analogues will be compared with that of other hemes. Difference may be suggestive of important mechanistic features of the enzymes. The interaction of nitrite and sulfite with siroheme analogues and subsequent reduction to products will be investigated.