Novel double bond-transferring hydroxylation reaction involved in microbial metabolism of eugenol.

We isolated a eugenol-degrading bacterium, Pseudomonas fluorescens E118. This strain produced a novel enzyme, eugenol dehydrogenase, which catalyzes the conversion of eugenol into coniferyl alcohol. The enzyme was purified from the eugenol-induced cells of P. fluorescens E118. The purified enzyme appeared to be homogeneous, judging from the analysis of polyacrylamide gel electrophoresis. The enzyme was a 68-kDa protein composed of two different subunits (alpha subunit, 10 kDa; and beta subunit, 58 kDa). The enzyme exhibited a cytochrome c-like absorption spectrum. The alpha subunit corresponded to cytochrome c. The enzyme catalyzed the dehydrogenation of 4-alkylphenol into the corresponding alkyl 1-(4-hydroxyphenyl)-alcohol derivatives. The reaction products were isolated and identified physicochemically. The enzyme catalyzed the enantioselective hydroxylation of p-alkylphenols. p-Ethylphenol and p-propylphenol were converted to S-(-)-p-(1-hydroxyphenyl)ethanol and S-(-)-p(1-hydroxyphenyl)propanol, respectively.