title: Fluorescence properties of Neurospora tyrosinase.
abstract: Some structural properties of Neurospora tyrosinase have been studied by fluorescence spectroscopy. The emission spectra observed for oxy-, deoxy-, met- and apo-tyrosinase and the Co2+-substituted form are indicative of a protein containing buried tryptophan residues. By using acrylamide and iodide, part of the emission is quenched, indicating heterogeneity in the tryptophan environment. Upon binding of Cu2+ or Co2+ to apo-tyrosinase, a marked decrease of the tryptophan quantum yield is observed. A further decrease in emission intensity results from the binding of molecular O2 to the deoxy form. The fluorescent probe 8-anilinonaphthalene-1-sulphonate binds to tyrosinase only when the metal ions are removed. Reconstitution of apo-tyrosinase with Cu2+ completely displaces the probe, suggesting that 8-anilinonaphthalene-1-sulphonate binds to apo-tyrosinase at the active site. The fluorescence properties of Neurospora tyrosinase are compared with those of haemocyanin.
mesh_terms: D020106:Acrylamide; D000178:Acrylamides / Q000494:pharmacology; D000817:Anilino Naphthalenesulfonates; D001665:Binding Sites; D004156:Catechol Oxidase / Q000378:metabolism*; D004735:Energy Transfer; D005456:Fluorescent Dyes / Q000494:pharmacology; D014442:Monophenol Monooxygenase / Q000378:metabolism*; D009491:Neurospora / Q000201:enzymology*; D009492:Neurospora crassa / Q000201:enzymology*; D011193:Potassium Iodide / Q000494:pharmacology; D013050:Spectrometry, Fluorescence; D014364:Tryptophan / Q000378:metabolism
chemical_list: D000178:Acrylamides; D000817:Anilino Naphthalenesulfonates; D005456:Fluorescent Dyes; D011193:Potassium Iodide; D020106:Acrylamide; C027132:1-anilino-8-naphthalenesulfonate; D014364:Tryptophan; D004156:Catechol Oxidase; D014442:Monophenol Monooxygenase