Reactivity of peroxo forms of the vanadium haloperoxidase cofactor. A DFT investigation.
Density functional theory has been used to investigate structural, electronic and reactivity properties of complexes related to the peroxo forms of vanadium haloperoxidases (VHPO). In particular, the reactivity of the cofactor as a function of protonation state and environment, which are two factors thought to be crucial in modulating the activity of the enzyme, has been examined. In full agreement with experimental data, results highlight the role of protonation in the activation of the peroxo-vanadium complexes and show that the oxo-transfer step involves the unprotonated axial peroxo oxygen atom, which is easily accessible to substrates in the peroxo form of the enzyme. The role of Lys353, which in the X-ray structure of the peroxide-bound form of vanadium chloroperoxidase is hydrogen bonded to the equatorial oxygen atom of the peroxo group, has been also explored. It is concluded that Lys353 can play a role similar to a H+ in the activation of the peroxo form of the cofactor.
Zampella
Giuseppe
G
Department of Biotechnology and Biosciences, University of Milano-Bicocca, Piazza della Scienza 2, 20126 Milan, Italy.
Fantucci
Piercarlo
P
Pecoraro
Vincent L
VL
De Gioia
Luca
L
D001203:Ascomycota / Q000201:enzymology; D002711:Chloride Peroxidase / Q000737:chemistry / Q000378:metabolism; D003067:Coenzymes / Q000737:chemistry / Q000378:metabolism; D007453:Iodide Peroxidase / Q000737:chemistry / Q000378:metabolism; D008958:Models, Molecular; D010544:Peroxidases / Q000737:chemistry* / Q000378:metabolism; D014639:Vanadium / Q000737:chemistry* / Q000378:metabolism; D014961:X-Ray Diffraction
D003067:Coenzymes; D014639:Vanadium; D010544:Peroxidases; C026195:bromide peroxidase; C418625:vanadium chloroperoxidase; C414928:vanadium iodoperoxidase; D002711:Chloride Peroxidase; D007453:Iodide Peroxidase