(S)-muconolactone = (4,5-dihydro-5-oxofuran-2-yl)-acetate Aromatic compound metabolism; beta-ketoadipate pathway; 5-oxo-4,5-dihydro-2-furylacetate from catechol: step 3/3. Homodecamer. Belongs to the muconolactone Delta-isomerase family.