Generation of hydrogen peroxide in the melanin biosynthesis pathway.
The generation of H(2)O(2) in the melanin biosynthesis pathway is of great importance because of its great cytotoxic capacity. However, there is controversy concerning the way in which H(2)O(2) is generated in this pathway. In this work we demonstrate that it is generated in a series of chemical reactions coupled to the enzymatic formation of o-quinones by tyrosinase acting on monophenols and o-diphenols and during the auto-oxidation of the o-diphenols and other intermediates in the pathway. The use of the enzymes such as catalase, superoxide dismutase and peroxidase helps reveal the H(2)O(2) generated. Based on the results obtained, we propose a scheme of enzymatic and non-enzymatic reactions that lead to the biosynthesis of melanins, which explains the formation of H(2)O(2).
Munoz-Munoz
Jose Luis
JL
GENZ: Grupo de Investigación de Enzimología, Departamento de Bioquímica y Biología Molecular-A, Facultad de Biología, Universidad de Murcia, E-30100, Espinardo, Murcia, Spain.
García-Molina
Francisco
F
Varón
Ramón
R
Tudela
José
J
García-Cánovas
Francisco
F
Rodríguez-López
Jose Neptuno
JN
D002374:Catalase / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000378:metabolism*; D008543:Melanins / Q000096:biosynthesis*; D014442:Monophenol Monooxygenase / Q000378:metabolism; D010084:Oxidation-Reduction; D010544:Peroxidases / Q000378:metabolism; D010636:Phenols / Q000378:metabolism; D013053:Spectrophotometry / Q000379:methods; D013482:Superoxide Dismutase / Q000378:metabolism
D008543:Melanins; D010636:Phenols; D006861:Hydrogen Peroxide; D010544:Peroxidases; D002374:Catalase; D014442:Monophenol Monooxygenase; D013482:Superoxide Dismutase