NADPH oxidation catalyzed by the peroxidase/H2O2 system. Iodide-mediated oxidation of NADPH to iodinated NADP.
Oxidation of NADPH catalyzed by the peroxidase/H2O2 system is known to require the presence of mediating molecules. Using either lactoperoxidase or horseradish peroxidase, we demonstrated that in the peroxidase/H2O2 system, NADPH oxidation was mediated by iodide. The oxidation product was the iodinated NADP. This product was shown to possess spectral characteristics different from those of NADP+ and NADPH, since for iodinated NADP, increased absorbance was observed in the 280-nm region and was directly proportional to the rate of iodination. It is suggested that oxidation and iodination of NADPH proceed via a single reaction between the intermediary iodide oxidation species and NADPH. Experiments with different molecules of NADPH analogues indicated that iodination occurred in the nicotinamide part of the NADPH molecule.
D002384:Catalysis; D055598:Chemical Phenomena; D002621:Chemistry; D006735:Horseradish Peroxidase / Q000378:metabolism; D007454:Iodides; D007784:Lactoperoxidase / Q000378:metabolism; D009249:NADP; D010084:Oxidation-Reduction; D010544:Peroxidases / Q000378:metabolism*; D013056:Spectrophotometry, Ultraviolet
D007454:Iodides; D009249:NADP; D006735:Horseradish Peroxidase; D007784:Lactoperoxidase; D010544:Peroxidases