title: Oxygenation of fluorinated tyrosines by mushroom tyrosinase releases fluoride ion.
abstract: The reactions of 2-fluoro- and 3-fluoro-L-tyrosine with mushroom tyrosinase have been investigated. Both fluorinated tyrosines are good substrates for tyrosinase, with Vmax and Vmax/Km values similar to those for L-tyrosine. Oxygenation of 2-fluorotyrosine is regioselective, and only 6-fluorodopa was detected by HPLC in reaction mixtures. Oxygenation of both isomers of monofluorotyrosine results in fluoride ion production in the absence of ascorbic acid; however, 2-fluorotyrosine also produces fluoride in the presence of ascorbic acid. These results are consistent with previous studies demonstrating rapid intramolecular cyclization of nascent 6-fluorodopaquinone (M.E. Rice, B. Moghaddan, C.R. Creveling, and K.L. Kirk, 1987, Anal. Chem. 59, 1534-1538), which is competitive with reduction by ascorbate, resulting in elimination of the aromatic fluorine as fluoride ion.
authors.affiliation: Department of Chemistry, School of Chemical Sciences, University of Georgia, Athens 30602.
authors.forename: R S
authors.initials: RS
authors.lastname: Phillips
authors.forename: J G
authors.initials: JG
authors.lastname: Fletcher
authors.forename: R L
authors.initials: RL
authors.lastname: Von Tersch
authors.forename: K L
authors.initials: KL
authors.lastname: Kirk
mesh_terms: D001487:Basidiomycota / Q000201:enzymology*; D004156:Catechol Oxidase / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid; D004295:Dihydroxyphenylalanine / Q000031:analogs & derivatives / Q000032:analysis; D005459:Fluorides / Q000032:analysis; D007700:Kinetics; D015394:Molecular Structure; D014442:Monophenol Monooxygenase / Q000378:metabolism*; D010084:Oxidation-Reduction; D014443:Tyrosine / Q000031:analogs & derivatives* / Q000378:metabolism
chemical_list: C001245:3-fluorotyrosine; C043437:fluorodopa F 18; D014443:Tyrosine; D004295:Dihydroxyphenylalanine; C060489:2-fluorotyrosine; D004156:Catechol Oxidase; D014442:Monophenol Monooxygenase; D005459:Fluorides