Tyrosinase-catalyzed oxidation of dopa and related catechol(amine)s: a kinetic electron spin resonance investigation using spin-stabilization and spin label oximetry. Biochim Biophys Acta 1987 Jun 22;924(3):383-92
Date
06/22/1987Pubmed ID
3036239DOI
10.1016/0304-4165(87)90152-8Scopus ID
2-s2.0-0023662391 (requires institutional sign-in at Scopus site) 67 CitationsAbstract
The oxidation of four catechol(amine)s by tyrosinase has been studied by electron spin resonance and optical methods. Rates of oxygen consumption and of dopaquinone and dopachrome formation during the oxidation of dopa have been measured, and compared with rates of dopasemiquinone production measured using spin-stabilization procedures. In the presence of spin-stabilizing metal ions, production of semiquinone is approximately quantitative. Time-dependent ESR spectra obtained from dopa and dopamine show a slow regeneration of semiquinone, suggesting that a semiquinone precursor is slowly reformed. In contrast, time-dependent spectra for 4-methylcatechol and N-acetyldopamine show decay of the primary semiquinone together with buildup of a secondary semiquinone apparently derived from the corresponding 6-hydroxy-catechol(amine). Thus, catecholamines that give rise to a cyclizable quinone show a pattern of behavior that differs from those that produce a non-cyclizable quinone. These results are discussed in terms of their possible significance to melanogenesis and the toxicity of catechol(amine)s, which has been attributed to production of semiquinones and/or other oxygen radicals.
Author List
Korytowski W, Sarna T, Kalyanaraman B, Sealy RCAuthor
Balaraman Kalyanaraman PhD Professor in the Biophysics department at Medical College of WisconsinMESH terms used to index this publication - Major topics in bold
BenzoquinonesCatalysis
Catechol Oxidase
Catecholamines
Catechols
Dihydroxyphenylalanine
Electron Spin Resonance Spectroscopy
Free Radicals
Indolequinones
Indoles
Kinetics
Monophenol Monooxygenase
Oxidation-Reduction
Oximetry
Quinones
Spin Labels