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 of allelochemical formation. The algae emit bromoform (CHBr3) depending on the enzyme activity level in vivo (Itoh, N., Shinya, M., 1994. Seasonal evolution of bromomethanes from coralline algae and its effect on atmospheric ozone. Marine Chemistry 45, 95-103). We demonstrated that bromoform produced by C. pilulifera played an important role in eliminating epiphytic organisms, especially microalgae on the surface. Such data suggest a strong relationship between the coralline algae and the coralline flat (deforested area in the marine environment: called isoyake in Japanese). Lithophyllum yessoense, the main inhabitant of coralline flats in Japan, produced a lower level 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 proportion to superoxide dismutase (SOD) activity and in inverse proportion to catalase activity. The phenomenon implies that BPO could be a potential substitute for catalase, because the enzyme catalyzes an efficient Br(-)-dependent catalase reaction.