Physiological function of bromoperoxidase in the red marine alga, Corallina pilulifera: production of bromoform as an allelochemical and the simultaneous elimination of hydrogen peroxide

The physiological function of vanadium-bromoperoxidase (BPO) in the marine red alga, Corallina pilulifera, has been characterized from the viewpoint o f allelochemical formation. The algae emit bromoform (CHBr3) depending on t he enzyme activity level in vivo (Itoh, N., Shinya, M., 1994. Seasonal evol ution of bromomethanes from coralline algae and its effect on atmospheric o zone. Marine Chemistry 45, 95-103). We demonstrated that bromoform produced by C. pilulifera played an important role in eliminating epiphytic organis ms, especially microalgae on the surface. Such data suggest a strong relati onship between the coralline algae and the coralline flat (deforested area in the marine environment: called isoyake in Japanese). Lithophyllum yessoe nse, the main inhabitant of coralline flats in Japan, produced a lower leve l of CHBr3 than C. pilulifera, and showed BPO activity. On the other hand, the seasonal change of BPO activity in C. pilulifera in vivo was in proport ion to superoxide dismutase (SOD) activity and in inverse proportion to cat alase activity. The phenomenon implies that BPO could be a potential substi tute for catalase, because the enzyme catalyzes an efficient Br--dependent catalase reaction. (C) 2001 Elsevier Science Ltd. All rights reserved.