STRUCTURAL MODELS FOR MOLYBDOENZYMES

钼是一种必需的微量元素，存在于相关的酶中 嘌呤代谢、硫代谢和无机物的同化 氮气 接触过量的钼与痛风有关， 土壤中的钼含量会影响硝酸盐和亚硝酸盐的含量， 也会干扰正常的铜代谢。 在人类中， 同时缺乏黄嘌呤氧化酶的酶活性， 已经证明，亚硫酸盐氧化酶是由于先天缺乏 “钼辅因子”是两种酶的基本成分。 这 研究旨在理解这种常见的钼辅因子， 其被认为是具有配位硫的单体钼中心 原子的 这项研究的一个目标是综合和 结构、化学和光谱表征钼 这些络合物是这些酶的钼中心的模型。 将特别强调含有单体的络合物， 连接到铁卟啉中心的氧代钼中心作为模型， 亚硫酸氧化酶 化合物及其与底物的反应， 通过电子顺磁共振技术， 共振光谱（EPR），光谱电化学，电子 光谱学和X射线晶体学。 第二个目标是直接 研究了亚硫酸盐氧化酶的钼中心， 的钼和铁中心之间的电子转移过程， 酶，并继续生长晶体的亚硫酸盐氧化酶与 最终目标是确定酶的三维结构。

Molybdenum is an essential trace element that is found in enzymes involved in purine metabolism, sulfur metabolism, and the assimilation of inorganic nitrogen. Exposure to excess molybdenum has been linked with gout, and molybdenum levels in the soil affect the levels of nitrate and nitrite and also interfere with normal copper metabolism. In humans, fatal simultaneous deficiencies in enzyme activity for xanthine oxidase and sulfite oxidase have been shown to result from an inborn deficiency of the "molybdenum cofactor," an essential constituent of both enzymes. This research is directed toward understanding this common molybdenum cofactor, which is thought to be a monomeric molybdenum center with ligating sulfur atoms. One objective of this research is to synthesize and to structurally, chemically and spectroscopically characterize molybdenum complexes which are models for the molybdenum centers of these enzymes. Special emphasis will be given to complexes containing a monomeric oxo-molybdenum center linked to an iron porphyrin center as a model for sulfite oxidase. The compounds and their reactions with substrates and inhibitors of molybdoenzymes win be studied by electron paramagnetic resonance spectroscopy (EPR), spectroelectrochemistry, electronic spectroscopy and x-ray crystallography. A second objective is to directly investigate the molybdenum center of the enzyme sulfite oxidase by studying electron transfer processes between the molybdenum and iron centers of the enzyme and by continuing to grow crystals of sulfite oxidase with the ultimate goal of determining the three dimensional structure of the enzyme.