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Studies on chemiluminescence in the enzymatic and autoxidative transformation of 3,4-dihydroxyphenylalanine into eumelanins

✍ Scribed by Villablanca, Miguel ;Indig, Guilermi ;Slawinska, Danuta ;Slawinski, Janusz

Book ID: 102760834
Publisher: John Wiley and Sons
Year: 1989
Weight: 759 KB
Volume: 3
Category: Article
ISSN: 0884-3996
DOI: 10.1002/bio.1170030405

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✦ Synopsis

The catechol oxidase-catalysed and autoxidative transformation of 3,4dihydroxyphenylalanine (DOPA) t o eumelanin have been studied by oxygen consumption, energy transfer, absorption and fluorescence spectroscopy. Formation of transient dopachrome ( A, , , = 480 nm) and dopalutin (bx = 423 nm, A, , = 491 nm) have been found in the enzymatic and autoxidative reaction. In the enzymatic reaction, neither a photon emission with quantum yield Q, > nor energy transfer t o triplet and singlet energy acceptors (sensitizers such as anthracene derivatives, xanthene dyes and chlorophyll-a) in water and micellar solutions have been found. The autoxidative reaction is chemiluminescent (@ = lo-'), the emission occurring in the 400-600nm range. The excitation energy is not transferred t o sensitizers. The effect of various enzymes and traps of active oxygen species as well as the spectral distribution of chemiluminescence indicate that there is no emission from oxygen dimoles. Carbonates and active species of oxygen are shown to participate in the chemiexcitation reaction.

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