The objectives of this research are to improve our understanding of vanadium in biological systems and our understanding of iron in the marine environment. In Part I we are focusing functional biomimetic studies of the essential vanadium ion in vanadium bromoperoxidase (vBrPO; an enzyme isolated from marine algae). V-BrPO is thought to be involved in the biosynthesis of the chiral halogenated and pseudohalogenated natural products, many of which have potent pharmacological activities. Dioxovanadium(V) is the first fully functional mimic of V-BrPO, catalyzing the oxidation of bromide by hydrogen peroxide which results in the formation of brominated organic substrates, or, in the absence of a substrate, the formation of dioxygen. The goal of Part I is to further elucidate the mechanism of the biomimetic system to understand the 10(4) difference in reactivity between V-BrPO it's optimum pH of ca. 6.5 and VO(O2)+ in 0.05 M acid. The approach is to investigate the reactivity of VO(O2)+, vanadium(V) complexes and other transition metal ions complexes towards halide oxidation by hydrogen peroxide, develop chiral halogenation reactions mediated by vanadium and other transition metals and investigate pseudohalogenation reactions mediated by the peroxovanadium(V) system. In Part II, we are focusing on the mechanisms of acquisition of iron (and other metal ions) by open ocean marine bacteria because the discrepancy between iron availability and requirements ranges between 2-5 orders of magnitude and because the transition metal composition of the oceans is extreme and unique. Molybdenum and vanadium are the two most abundant transition metal ions in surface seawater. All microorganisms, with the possible exception of lactobacilli, require iron for growth. It is surprising that so little is known about mechanisms of iron acquisition by marine microorganisms. We are focusing first on the structures of siderophores produced by marine bacteria to determine 1) whether these bacteria produce siderophores that complex iron more tightly than other siderophores, 2) whether their metal binding selectivity is different from terrestrial siderophores and 3) whether the metal uptake mechanisms (metal regulation, pathways, outer membrane proteins) of the marine bacteria differ from terrestrial bacteria.
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