Purification and characterization of the vanadium bromoperoxidase from the macroalga Corallina officinalis

The red macroalga Corallina officinalis contains a bromoperoxidase whose activity is vanadium-dependent. This enzyme has been purified to homogeneity as judged from non-denaturing PAGE and SDS-PAGE. Sedimentation equilibrium studies gave a value for Mr of 740 000, whereas a Mr of 64 000 was obtained by SDS-PAGE. The native enzyme thus appears to be an oligomer, probably of 12 identical subunits. Kinetic studies for the bromination of monochlorodimedone (MCD) gave the following: Km(Br-), 1.0 mM; Km(H2O2), 60 micromolar and Km(MCD), 21 micromolar. The bromoperoxidase showed remarkable thermostability, retaining appreciable activity at 60-70 degrees and recovering the original activity on re-equilibration to 25 degrees, even on repeated cycles of this temperature regime. The enzyme also showed tolerance to a range of organic solvents and chaotropic agents.