Studies of the Chaotic Behaviour in the Peroxidase-Oxidase Reaction

This note presents experimental results with an enzyme-catalysed reaction with a continuous supply of the substrates in which we observe a transition from periodic behaviour to apparently nonperiodic behaviour by decreasing the enzyme concentration. A model of the reaction is also described. This model, based only on elementary reaction steps, can simulate the periodic behaviour observed experimentally. By changing only one rate constant the behaviour changes from periodic to quasi-periodic behaviour. The work of earlier investigators suggests that such quasiperiodic behaviour (toroidal oscillations) is a step towards chaotic behaviour.