Dr. Hille will continue his study of the molybdenum hydroxylase, xanthine oxidase. He will fully characterize the enzyme from a physical stand point with particular regard to features likely to be relevant to catalysis. For a variety of reasons, xanthine oxidase has become the prototypical molybdenum hydroxylase, a small but important class of metalloproteins. Physicochemical studies of the enzyme lie at the forefront of understanding molybdenum enzymes and will provide important insight into the general features of biological electron transfer processes. Molybdenum hydroxylases are members of a small but extremely important class of enzymes that are responsible for the incorporation of oxygen into a variety of organic and inorganic compounds. They are not well understood in comparison to other hydroxylating systems. This is due in large part to the absence of experimental probes for molybdenum centers, which lack the convenient spectrophotometric properties exhibited by other oxidation - reduction centers. Nevertheless, the presently available information regarding the mechanism of action of the molybdenum hydroxylase suggests several fascinating aspects of these enzymes.
