Vanillyl-alcohol oxidase, a tasteful biocatalyst

The covalent flavoenzyme vanillyl-alcohol oxidase (VAO) is a versatile bioc atalyst. It converts a wide range of phenolic compounds by catalysing oxida tion, deamination, demethylation, dehydrogenation and hydroxylation reactio ns. The production of natural vanillin, 4-hydroxybenzaldehyde, coniferyl al cohol and enantiomeric pure phenol derivatives is of interest for technolog ical applications. The hydroxylation of 4-alkylphenols is highly stereospec ific for the (R)-isomer, whereas hydrogenation of these substrates is speci fic for the cis- or trans-isomer. On the basis of crystallographic data, we suggest the stereospecificity is related to the active site residue Asp170 . Another important feature of VAO is the covalent flavin attachment, Studi es from site-directed mutants suggest that the covalent flavin-protein inte raction improves the catalytic performance as well as the long-term stabili ty of VAO. (C) 2001 Elsevier Science B.V. AU rights reserved.