Characterization of the reaction between cytochrome c peroxidase and potassium hexachloroiridate
This thesis characterizes the reaction between K2IrCl6 and ZnCcP. This reaction was compared to previously reported data of the reaction between K2IrCl6 and two other heme proteins, metmyoglobin (metmb) and horseradish peroxidase (HRP). The reactions were monitored spectrophotometrically using diode array and stopped flow instruments. To characterize the reaction between ZnCcP and K2IrCl6, the objectives were to (1) generate the spectrum of the ZnCcP porphyrin cation radical, (2) to generate the equilibrium constant for the reaction, and (3) to generate the electron transfer rate constants. The results of the experiments showed that ZnCcP behaves differently than metmb or HRP. Previously reported data show that the reaction between K2IrCl6 and HRP and metmb have few side reactions. The reaction between ZnCcP and K2IrCl6 has a large number of side reactions. Also, the concentration of K2IrCl6 goes to zero indicating that there is no equilibrium between ZnCcP and K2IrCl6. The values for the electron transfer rate constants are about 2 s'-1 and 0.3 s'-1. The spectral data suggest that oxidation of the porphyrin ring occurs through oxidation of surface tryptophan residues.