Theoretical investigation of the peroxidase-oxidase chemical oscillator for quantitative enzyme analysis

The theoretical basis for quantitative enzyme determinations by using the features of chemical oscillations is developed. An existing model of the peroxidase-oxidase chemical oscillator, consisting of the enzyme horseradish peroxidase, oxygen and reduced nicotinamide adenine dinucleotide (NADH), is modified to include a competing (analyte) reaction. The competitive effect between the analyte and the peroxidase on the observed periodic and chaotic oscillations forms the basis of the modified model. Corresponding differential equations are numerically integrated to produce plots of dissolved oxygen concentration vs. time. The calculated oscillatory oxygen transient shows a sensitive dependence on the analyte concentration. Utilizing the property of period doubling, a theoretical calibration graph can be generated for the determination of an analyte enzyme concentration. Special properties of the technique offer a potential combination of wide dynamic range and selectable precision. This demonstrates that the oscillator should prove experimentally useful for quantitative analysis.