KINETICS OF THE PEROXIDASE OXIDASE REACTION WITH IMMOBILIZED ENZYME

Reaction rate studies of the peroxidase-oxidase (PO) reaction were conducted utilizing horseradish peroxidase (HRP) immobilized in cross-linked bovine serum albumin (BSA), an inert protein matrix. It was found that the membrane potential was a valid indicator of the extent of reaction and could be used to follow the kinetics. The rate of reaction in the immobilized system was determined to be approximately 10 times slower than with free enzyme, a result consistent with well-accepted theories of immobilized enzyme kinetics. The measurement of membrane potential thus provides an alternative method to the established spectrophotometric and oxygen-selective electrode techniques for monitoring the PO reaction in vitro. In addition, preliminary evidence of nonlinear behavior in the form of damped oscillations was found. The sawtooth shape and period (1-2 min) of the oscillations observed are similar to those seen with free enzyme, but the amplitude was found to be 10-25 times larger. Since some HRP is found to be immobilized in the cell wall in vivo, these observations lend tentative support to the possibility that in vivo oscillations in the PO reaction might also occur.