Optimizing the o-phenylenediamine assay for horseradish peroxidase: effects of phosphate and pH, substrate and enzyme concentrations, and stopping reagents.

Horseradish peroxidase, assayed with o-phenylenediamine, is irreversibly inactivated when incubated in phosphate buffer, 100 mmol/L, at pH 5. The inactivation depends on both duration and incubation and phosphate concentration. Phosphate was the most potent inactivator and citrate the least potent of a series of buffers tested. The inactivation is not… CONTINUE READING