Isolation and characterization of vanadium bromoperoxidase from a marine macroalga, Ecklonia stolonifera

The bromoperoxidase has been isolated from the marine brown alga, Ecklonia stolonifera (83 kDa) and has been characterized. Bromoperoxidase requires vanadium for enzyme activity as has been evidenced by EPR spectroscopy. The enzyme activity increased ca. 250% with the action of V5+ on the isolated enzyme, since more than 2/3 of the protein molecules were in the apo form. The increase in the enzyme activity was specific to V5+, while Fe2+, Fe3+, and Cu2+ inhibited the enzyme activity. This effect of V5+ addition was inhibited in phosphate buffer, probably because phosphate and vanadate compete for the active site. The bromoperoxidase exhibited a high thermostability (Tm = 68 degrees C) and a high stability in organic solvents (completely intact even in the presence of 50% methanol, ethanol and 1-propanol).