Flavoenzyme-Catalyzed Oxygenations and Oxidations of Phenolic Compounds

Flavin-dependent monooxygenases and oxidases play an important role in the mineralization of phenolic compounds. Because of their exquisite regioselectivity and stereoselectivity, these enzymes are of interest for the biocatalytic production of fine chemicals and food ingredients. In our group, we have characterized several flavoenzymes that act on phenolic compounds, including 4-hydroxybenzoate 3-hydroxylase, 3-hydroxyphenylacetate 6-hydroxylase, 4-hydroxybenzoate 1-hydroxylase (decarboxylating), hydroquinone hydroxylase, 2-hydroxybiphenyl 3-monooxygenase, phenol hydroxylase, 4-hydroxyacetophenone monooxygenase and vanillyl-alcohol oxidase. The catalytic properties of these enzymes are reviewed here, together with insights obtained from site-directed and random mutagenesis.