Mechanism of Interfbrence of Bilirubin on the Peroxidase-Coupling Reactions

Abstract

The mechanism of interference of bilirubin on the peroxidase reaction systems is discussed from spectrophotometric and kinetic findings.
1. In the oxidative coupling reaction system with 4-aminoantipyrine and phenol, bilirubin reacted with the phenol intermediate produced by peroxidase reaction. Then, bilirubin interfered on the peroxidase reaction according to a competitive inhibition against the same acceptor for the phenol intermediate, 4-aminoantipyrine.
2. Bilirubin, also, interfered on the peroxidase reaction as a hydrogen donor of peroxidase and this interference resulted in a competitive inhibition to the same hydrogen donor such as phenol, ABTS, o-dianisidine. Increasing the concentrations of the hydrogen donors, rger Ki values were obtained.
3. The interference of bilirubin was partialy dependent on the measuring wavelength. Setting the measuring wavelength longer than 520nm, the apparent interference of bilirubin was reduced by the production of biliverdin or another unknown complex with the phenol intermediate.