COORDINATION CHEMISTRY OF VANADIUM IN BIOLOGY SYSTEM

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DESCRIPTION (Adapted from the Investigator's Abstract): The presence of vanadium in biological systems is well established. Amavadine from the mushroom a.muscaria, the V(III)-tunichrome system in the blood cells of tunicates, bromoperoxidases from several species of marine algae and a vanadium containing nitrogenase from azotobacter vinelandii are salient examples. It is also now clear that vanadium has a number of important environmental, toxicological and physiological effects. Despite its presence, virtually nothing whatever is known about the structure, function or chemistry of vanadium in any of these systems. Experiments in this proposal are designed to help outline possible structures, oxidation states and ligation of vanadium that give rise to the physicochemical properties of these biomolecules. Accurate structural information is of paramount importance to an understanding of the role of vanadium in biology. A comparison between well-defined small molecule models and the biomolecules themselves represents one viable means of achieving this goal. The investigators propose to use model compounds to help investigate two particular areas of interest: 1) the structure and mechanism of action of first true vanadoenzyme, "bromoperoxidase" and 2) the mechanism of accumulation, and biological function of, vanadium in tunicates. Specific questions/goals to be addressed include: 1) For Bromoperoxidase: The production of accurate small molecule mimics for the active site which will give information about its structure and function along with investigations into the mechanism of action of the enzyme. These investigations will involve the synthesis of new vanadium complexes and their complete characterization. Such characterization will include UV-vis spectro-photometry, NMR (1H, 13C and 51V as appropriate), EPR, magnetic measurements, electrochemistry and, when appropriate, single crystal X-ray diffraction. 2) For Tunicates: To understand the interaction between vanadium and the tunichromes and to determine the mechanism of the reduction/accumulation process involved in its uptake. From these studies the investigators also hope to be able to understand the biological function of the vanadium in these organisms. These studies will involve resonance Raman and magnetic susceptibility studies on both model compounds and actual tunicate blood. The successful conclusion of this research project will provide a sound basis to increase the investigators understanding of the role of vanadium in many biological systems.