Vanadium active site structure

Elamstra BH, Houseman ALP, Colpas GJ, Kampf R, LoBrutto R, Frasch WD, Pecoraro VL. 1997. Structural and solution characterization of mononuclear vanadium(IV) complexes that help to elucidate the active site structure of the reduced vanadium haloper-oxidases. Inorg Chem 36 4866-4874. 

Figure 17.13 The structure and active site of the bromoperoxidase subunit from C. pilulifera. Residues conserved in all vanadium bromo- and chloroperoxidases are in grey, those that vary in cyan. (From Ohshiro et al., 2004. Copyright 2004 The Protein Society.)...

It is also of interest to point out that the amino acid sequence and structure of the active site of vanadium haloperoxidases is conserved within several families of phosphatases, with conservation of the amino acids involved in vanadate binding in one and phosphate binding in the other. 

Newer types of the dinuclear vanadium(IV) complex catalysts 84 have been developed. The abovementioned dinuclear vanadium complexes possess a VO V linkage whereas the ESR study on the catalyst 84 revealed no V—O—V linkage. The sense of enantioselection by the catalyst 84 of the (R,5,5)-structure is opposite to that of the binuclear complex 78a of the same (R,5,5)-structure. These results suggested two active sites attached to the binaphthyl skeleton in the catalyst 84 performed the dual activation of 2-naphthols in the oxidative couphng to achieve high enantioselectivity ... 

Vanadium CPO from Curvularia inaequalis has also been the object of both experimental (2146, 2172-2175, 2329) (for an X-ray structure see Fig. 4.1) and theoretical studies (2176) to understand the biohalogenation operation of this enzyme. A reasonable mechanism has emerged from these data (Scheme 4.2) (active site amino acids and H-bonds are deleted for clarity). The nature of the halide-vanadium intermediate is unknown. 

Macedo-Ribeiro S, Hemrika W, Renirie R, Wever R, Messerschmidt A (1999) X-Ray Crystal Structures of Active Site Mutants of the Vanadium-Containing Chloroperoxidase from the Fungus Curvularia inaequalis. J Biol Inorg Chem 4 209... 

Conte, V., O. Bortolini, M. Carraro, and S. Moro. 2000. Models for the active site of vanadium-dependent haloperoxidases Insight into the solution structure of peroxo-vanadium compounds. J. Inorg. Biochem. 80 41 -9. 

Macedo-Ribeiro, S., Hemrika, W., Renirie, R., Wever, R. and Messerschmidt, A. (1999). X-ray crystal structure of active site mutants of the vanadium-containing chloroperoxidase from the fungus Curvularia inaequalis. Journal of Biological Inorganic Chemistry, 4,209-219. 

Contents E. I. Solomon, K. W.Penfield, D.E. Wilcox Active Sites in Copper Proteins. An Electronic Structure Overview. -B.A.Averill Fe-S and Mo-Fe-S Clusters as Models for the Active Site of Nitrogenase. - N.D. Chasteen The Biochemistry of Vanadium. -KKustin, G.C. McLeod, T.R. Gilbert,... 

Figure 1. Proposed structure of the active site of vanadium bromoperoxidase based on EXAFS data (17).

Vanadium phosphates have been established as selective hydrocarbon oxidation catalysts for more than 40 years. Their primary use commercially has been in the production of maleic anhydride (MA) from n-butane. During this period, improvements in the yield of MA have been sought. Strategies to achieve these improvements have included the addition of secondary metal ions to the catalyst, optimization of the catalyst precursor formation, and intensification of the selective oxidation process through improved reactor technology. The mechanism of the reaction continues to be an active subject of research, and the role of the bulk catalyst structure and an amorphous surface layer are considered here with respect to the various V-P-O phases present. The active site of the catalyst is considered to consist of V and V couples, and their respective incidence and roles are examined in detail here. The complex and extensive nature of the oxidation, which for butane oxidation to MA is a 14-electron transfer process, is of broad importance, particularly in view of the applications of vanadium phosphate catalysts to other processes. A perspective on the future use of vanadium phosphate catalysts is included in this review. 

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