ISSN:
1600-0757
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Medicine
Notes:
Ultraweak luminescence in the spectral region 300–660 nm is generated in the enzymatic (tyrosinase EC.1.14.18.1) and autooxidative polymerization of l-DOPA, 5-S-cys-teinyl-DOPA, and l-DOPA + cysteine to eumelanins and pheomelanins, respectively. Using sensitive calibrated single photon counting equipment, the photon emission intensity I and quantum yield φ have been measured: I = 10–100 hν/s cm3, φ≤ 10–13 for enzymatic reactions, and I = 500–3000 hν/s cm3, φ≥ 5 × 10–12 for autooxidative ones. 5-S-cysteinyl-DOPA and cysteine exhibit diminished I and φ-values relative to DOPA. Tests with chemiluminogenic probes-luminol and lucigenin, SOD, catalase, peroxidase, H2O2, and spectrophotometric measurements indicate that photon emission is associated with degradative oxidations of melanin subunits by means of active oxygen species as H2O2 and O2.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1111/j.1600-0749.1987.tb00409.x
