title: Direction of the reactivity of vanillyl-alcohol oxidase with 4-alkylphenols.
abstract: The covalent flavoprotein vanillyl-alcohol oxidase (VAO) predominantly converts short-chain 4-alkylphenols, like 4-ethylphenol, to (R)-1-(4'-hydroxyphenyl)alcohols and medium-chain 4-alkylphenols, like 4-butylphenol, to 1-(4'-hydroxyphenyl)alkenes. Crystallographic studies have indicated that the active site residue Asp170 is involved in determining the efficiency of substrate hydroxylation. To test this hypothesis, we have addressed the reactivity of Asp170 variants with 4-alkylphenols. The substrate preference of Asp170Glu was similar to wild type VAO. However, Asp170Ser was most active with branched-chain 4-alkylphenols. The hydroxylation efficiency of the Asp170 variants was dependent on the bulkiness of the newly introduced side chain. The Glu170 mutation favored the production of alkenes, whereas the Ser170 mutation stimulated the formation of alcohols.
authors.affiliation: Laboratory of Biochemistry, Department of Biomolecular Sciences, Wageningen University, Dreijenlaan 3, 6703 HA Wageningen, The Netherlands.
authors.forename: R H
authors.initials: RH
authors.lastname: van den Heuvel
authors.forename: M W
authors.initials: MW
authors.lastname: Fraaije
authors.forename: W J
authors.initials: WJ
authors.lastname: van Berkel
mesh_terms: D000429:Alcohol Oxidoreductases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D019943:Amino Acid Substitution; D001224:Aspartic Acid / Q000235:genetics / Q000378:metabolism; D001665:Binding Sites; D006900:Hydroxylation; D007700:Kinetics; D009154:Mutation; D010407:Penicillium / Q000201:enzymology*; D010636:Phenols / Q000737:chemistry* / Q000378:metabolism*; D013050:Spectrometry, Fluorescence; D013379:Substrate Specificity
chemical_list: D010636:Phenols; D001224:Aspartic Acid; D000429:Alcohol Oxidoreductases; C076865:vanillyl-alcohol oxidase