Arenes with an Oxygenated C2 or C3 Side Chain

Several pathways are used for the aerobic degradation of aromatic compounds with an oxygenated C2 or C3 side chain. These include acetophenones and reduced compounds that may be oxidized to acetophenones, and compounds including tropic acid, styrene, and phenylethylamine that can be metabolized to phenylacetate, which has already been discussed. 

Although the metabolism of vanillate generally involves de-O-methylation to 3,4-dihy-droxybenzoate followed by intradiol ring hssion, in Acinetobacter Iwoffii vanillate is hydroxylated to 3-0-methyl gallate, which produces pyruvate and oxalacetate in reactions that have already been noted (Sze and Dagley 1987). 

The metabolism of ferulate to vanillin by Pseudomonas fluorescens strain AN103 is carried out by an enoyl-SCoA hydratase/isomerase rather than by oxidation, and the enzyme belongs to the enoyl-CoA hydratase superfamily (Gasson et al. 1998). 

FIGURE 8.35 Degradation of (a) mandelate, (b) 4-hydroxyacetophenone by side-chain oxidation pathways, (c) acetophenone by Baeyer-Villiger monooxygenation. 

A strain of Pseudomonas sp. ATS degraded tropic acid, which has a -CH-(CH20H)-COjH side chain to phenylacetate (Long et al. 1997). 

---