J. Biol. Chem., Vol. 262, Issue 25, 11982-11987, 09, 1987

Characterization of nonheme iron and reaction mechanism of bromoperoxidase in Corallina pilulifera

N Itoh, Y Izumi and H Yamada

The properties of the nonheme iron of bromoperoxidase from Corallina pilulifera were studied. The enzyme lost its activity when reduced with formamidine-sulfinic acid and recovered it when oxidized by air. Incubation of the enzyme with ferric or ferrous ion-chelating agents indicated that its nonheme iron was ferric. Analyses of circular dichroism and proton NMR spectra suggested that the ferric ion tightly bound to cysteine, histidine, or tyrosine residues of the enzyme. The enzyme catalyzed Br--dependent catalase reactions to yield 1 mol of O2 from 2 mol of H2O2. No O2 evolution was observed when bromination reaction of monochlorodimedone occurred. From these results, together with previous knowledge of this enzyme, it was concluded that it activated bromide anion (Br-) to bromonium cation (Br+) using one molecule of H2O2, and this Br+OH- formed at the active site then decomposed another H2O2 to yield O2 in the absence of halogen acceptors (substrate). When substrate was present in the reaction mixture, it and H2O2 competitively reacted with the reaction intermediate (Br+OH-) to give brominated products.
CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    What's this?

This article has been cited by other articles:

				T. Ohshiro, J. Littlechild, E. Garcia-Rodriguez, M. N. Isupov, Y. Iida, T. Kobayashi, and Y. Izumi Modification of halogen specificity of a vanadium-dependent bromoperoxidase Protein Sci., June 1, 2004; 13(6): 1566 - 1571. [Abstract] [Full Text] [PDF]