Physiochemical Studies on Xanthine Oxidizing Enzymes

Massey博士正在继续他对牛奶黄嘌呤氧化酶的研究，研究酶的四个氧化还原中心的化学、物理和结构特性以及它们之间的相互作用。该项目还将与两种密切相关的酶进行比较研究，即牛奶酶的脱氢酶形式和鸡肝脏中稳定的黄嘌呤脱氢酶。将主要使用止流光学技术来监测各种条件下氧化还原中心的氧化和还原，以及广泛使用13C NMR来研究底物的相互作用。以钼为中心的产物和抑制剂。黄嘌呤氧化酶是一种被充分研究的含钼羟化酶，对该酶的研究是我们努力建立钼中心结构和在这类小而重要的酶中起作用的化学机制的前沿。由于黄嘌呤氧化酶含有不少于4个能够可逆地吸收还原物的中心，因此该酶还可以作为更复杂的光合作用和线粒体电子传递系统中氧化还原活性中心相互作用的有用模型。＊＊＊

Dr. Massey is continuing his study of milk xanthine oxidase in which the chemical, physical and structural properties of the four redox centers of the enzyme and the interactions between them will be examined. The project will also include a comparative study with two closely related enzymes, the dehydrogenase form of the milk enzyme and the stable xanthine dehydrogenase from chicken liver. Major use will be made of stopped flow optical techniques to monitor oxidation and reduction of the redox centers under various conditions as well as extensive use of 13C NMR to study the interaction of substrates, products and inhibitors with the molybdenum center. Xanthine oxidase is a well-studied molybdenum-containing hydroxylase and studies on the enzyme lie at the forefront of our efforts to establish the structure of the molybdenum centers and the chemical mechanisms operative in this small but important class of enzymes. Because xanthine oxidase contains no fewer than four centers capable of reversibly taking up reducing equivalents, the enzyme also serves as a useful model for the interaction of redox-active centers in the more complicated systems of photosynthetic and mitochondrial electron transport. ***