title: The non-photosensitized potentiation by the photosensitizer hematoporphyrin of the horseradish peroxidase-catalyzed H2O2-mediated oxidation of NADPH to NADP+.
abstract: Horseradish peroxidase is known to oxidize NADPH in a reaction initiated by hydrogen peroxide. The present study demonstrates that the photosensitizer hematoporphyrin acting in a non-photodynamic manner, has a marked potentiating effect on the nucleotide oxidation rate. Over 90 percent of the NADPH oxidation product is enzymatically active NADP+. The ratio of NADPH oxidized to NADPH added indicates the existence of a chain reaction. It is suggested that the enzymatic generation of hematoporphyrin transients which are usually generated photodynamically, may be responsible for the acceleration in rate of reduced nucleotide oxidation.
mesh_terms: D002374:Catalase / Q000378:metabolism; D006415:Hematoporphyrins / Q000494:pharmacology*; D006735:Horseradish Peroxidase / Q000378:metabolism*; D006861:Hydrogen Peroxide / Q000378:metabolism*; D007700:Kinetics; D009249:NADP / Q000378:metabolism*; D010084:Oxidation-Reduction; D010544:Peroxidases / Q000378:metabolism*; D010777:Photochemistry; D013053:Spectrophotometry; D013997:Time Factors
chemical_list: D006415:Hematoporphyrins; D009249:NADP; D006861:Hydrogen Peroxide; D006735:Horseradish Peroxidase; D010544:Peroxidases; D002374:Catalase