The Peroxidase-NADH Biochemical Oscillator. 1. Examination of Oxygen Mass Transport, the Effect of Light, and the Role of Methylene Blue

Article abstract of DOI:10.1021/j100004a021

The peroxidase-NADH oscillator examined here initially consists of four chemical components.The well-mixed aqueous solution includes native horseradish peroxidase, reduced β-nicotinamide adenine dinucleotide (NADH), methylene blue (MB⁺), and dissolved oxygen combined in a semi-batch reactor under a set of standard conditions.In this system, the macroscopic appearance of the process of oxygen dissolution from the gas phase is dependent on k_-m, the mass transport constant of oxygen out of solution.Additional details of oxygen mass transport are derived.The amplitude of oxygen oscillations is decreased by continuous illumination by the deuterium source of a diode array spectrophotometer.This attenuation effect of light is dependent on wavelengths =< 248 nm.Initial omission of MB⁺ allows several damped oscillations of small amplitude.Subsequent addition of MB⁺ to the oscillator results in oscillations of much larger amplitude.MB⁺ is seen to either directly or indirectly enhance the conversion of peroxidase compound III to the native enzyme and then inhibit oxygen consumption, allowing the initiation of relatively large, prolonged oscillations.MB⁺ is seen to function either as a system catalyst, or as a peroxidase inhibitor in the oxidation of NADH by oxygen.