X-Ray Absorption Spectroscopic Studies of Vanado-Enzymes: Nitrogenase and Bromoperoxidase
Vanadium is well recognised as an essential trace element, is widely distributed throughout the lithosphere and biosphere, and is present in all mammalian tissues at concentrations of ≤ 10μM (Chasteen, 1983). However, only in a few instances can a precise biological role be assigned to this element. It is a potent inhibitor of phosphatases, Na,K-ATPases, and a variety of other important enzymes, doubtless because of the similarity of AO4 3- (for A=V or P) and their derivatives. Amavadín, an oxovanadium(IV) complex with two molecules of N-(1-carboxyethyl)-N-hydroxyalanine, has been isolated from the mushroom Amanita muscaria (Kneifel and Bayer, 1986) and may function as an electron-transfer catalyst (Nawi and Riechel, 1987). Two enzyme systems were shown to be dependent upon vanadium: nitrogenases from Azotobacter (Robson et al., 1986) and bromoperoxidases from marine algae (de Boer et al., 1986; de Boer et al., 1986). Herein we describe the results of vanadium K-edge X-ray absorption spectroscopic studies for a member of each of these two types of vanadium-dependent enzymes.
KeywordsNative Enzyme Titanium Foil Ascophyllum Nodosum Photon Factory Enzyme Turnover
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