Inversion of stereospecificity of vanillyl-alcohol oxidase

R.H.H. van den Heuvel, M.W. Fraaije, A. Mattevi, M. Ferrer, W.J.H. van Berkel

Research output: Contribution to journalArticleAcademicpeer-review

55 Citations (Scopus)

Abstract

Vanillyl-alcohol oxidase (VAO) is the prototype of a newly recognized family of structurally related oxidoreductases sharing a conserved FAD-binding domain. The active site of VAO is formed by a cavity where the enzyme is able to catalyze many reactions with phenolic substrates. Among these reactions is the stereospecific hydroxylation of 4-ethylphenol-forming (R)-1-(4'-hydroxyphenyl)ethanol. During this conversion, Asp-170 is probably critical for the hydration of the initially formed p-quinone methide intermediate. By site-directed mutagenesis, the putative active site base has been relocated to the opposite face of the active site cavity. In this way, a change in stereospecificity has been achieved. Like native VAO, the single mutants T457E, D170A, and D170S preferentially converted 4-ethylphenol to the (R)-enantiomer of 1-(4'-hydroxyphenyl)ethanol. The double mutants D170A/T457E and D170S/T457E exhibited an inverted stereospecificity with 4-ethylphenol. Particularly, D170S/T457E was strongly (S)-selective, with an enantiomeric excess of 80ÐThe crystal structure of D170S/T457E, in complex with trifluoromethylphenol, showed a highly conserved mode of ligand binding and revealed that the distinctive catalytic properties of this mutant are not caused by major structural changes.
Original languageEnglish
Pages (from-to)9455-9460
JournalProceedings of the National Academy of Sciences of the United States of America
Volume97
DOIs
Publication statusPublished - 2000

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