The bromoperoxidase from the lichen Xanthoria parietina is a novel vanadium enzyme

A novel bromoperoxidase was isolated from the lichen Xanthoria parietina. The enzyme contained vanadium, which is essential for enzymic activity. Under denaturating conditions the preparation showed a single protein band with an Mr of 65,000. Thermal-denaturation studies showed that this bromoperoxidase could tolerate high temperatures. The affinity of the enzyme for its substrate bromide is high; the Km for bromide was 29 microM. Excess halides (50 mM) inhibited enzymic activity considerably.