NEW REACTION-MECHANISM FOR THE OSCILLATORY PEROXIDASE OXIDASE REACTION AND COMPARISON WITH EXPERIMENTS

We present a new model for the oscillatory peroxidase-oxidase reaction, which is an extension of the recent model C (Aguda, B. D.; Larter, R. J. Am. Chem. Soc. 1991, 113, 7913) and includes reaction steps involving 2,4-dichlorophenol and termination reactions for the superoxide radical and hydrogen peroxide. The calculations with this model compare well with measurements of temporal variations, including mixed-mode, chaotic, and bursting oscillations as well as tests for the assignment of roles of the species in the model and the categorization of the oscillator (Eiswirth, M.; Freund, A.; Ross, J. Adv. Chem. Phys. 1991, 80, 127). Of the 12 species considered in this model, six are essential, and the others nonessential. The essential species are oxygen, compound I, compound II, compound III, the NAD radical, and the superoxide radical. The nature of these essential species is also identified. Of the four species (oxygen, NADH, native HRP, and compound III) measured experimentally, oxygen and compound UI have been determined to be essential. The category of this model is 1CW, in accordance with the experimental results. The new model reproduces better than the earlier models the temporal variations observed experimentally.