Structure and function of the xanthine-oxidase family of molybdenum enzymes

Abstract

This work gives an account of the recent achievements which have contributed towards the understanding of the structure and function of the xanthine oxidase family of enzymes-the molybdenum hydroxylases. It is based essentially on the crystallographic data of the aldehyde oxido-reductase from Desulfovibrio (D.) gigas, a member of that family, whose structure is described in detail. Comparisons are made, whenever appropriate, with spectroscopic, kinetic and model compound studies. Mechanistic implications of the crystal structure of the D. gigas enzyme are considered and extended to the xanthine oxidase family.

Structural and Electron Paramagnetic Resonance (EPR) Studies of Mononuclear Molybdenum Enzymes from Sulfate-Reducing Bacteria

“…The pyranopterin molecule is an organic ligand that can be either in the monophosphate form or have a nucleotide molecule attached by a pyrophosphate link (Figure 1b). 7 In addition, these proteins may also have other redox cofactors such as iron-sulfur (FeS) centers, hemes, and flavin groups, which are involved in intra-and intermolecular electron-transfer processes. A tungstencontaining aldehyde oxidoreductase from Pyrococcus furiosus presents a similar active-site structure and has been classified in a different family.…”

EPR spectroscopy: A powerful technique for the structural and functional investigation of metalloproteins

“…The active site of this redox enzyme is a molybdenum center, and electron transfer to its physiological partners is ensured by two [2Fe-2S] 1ϩ,2ϩ centers. 20 When this enzyme was reduced with sodium dithionite, a Mo(V) signal centered at g ϭ 1.97 and signals I (g x ϭ 1.919, g y ϭ 1.938, g z ϭ 2.020) and II (g x ϭ 1.900, g y ϭ 1.97, g z ϭ 2.057) arising from the two [2Fe-2S] 1ϩ centers were clearly visible in the X-band EPR spec- In the fully oxidized form three hemes give components at g z1 ϭ 2.724, g z2 ϭ 3.091, and g z3 ϭ 2.963 and the fourth heme is present under two conformations giving components at g z4 ϭ 2.950 and g z4Ј ϭ 2.801. S10 trum (Fig.…”

Synthetic Bioinorganic Chemistry: Scorpionates Turn 50

“…Molybdenum, the only second-row transition metal recognized as an essential trace element in human nutrition [49], is present as a cofactor in most nitrogenases ligands are applied to model the molybdenum centers in sulfite oxidase, xanthine oxidase/dehydrogenase, nitrate reductase, and dimethyl sulfoxide (DMSO) reductase enzymes [52][53][54]. In a similar vein, the active centers in tungsten-containing enzymes such as aldehyde oxidoreductase and formate dehydrogenase [55,56] have been modeled using a variety of Tp RR 0 complexes [52,57], as exemplified by an ene-1,2-dithiolate complex (Fig.…”