3-Carboxy-cis,cis-muconic acid is a metabolite of the catechin degradation by Bradyrhizobium japonicum.
The enzyme protocatechuate 3,4-dioxygenase found in Pseudomonas aeruginosa uses protocatechuic acid and oxygen to produce 3-carboxy-cis,cis-muconate.
The enzyme 3-carboxy-cis,cis-muconate cycloisomerase found in Pseudomonas putida converts 3-carboxy-cis,cis-muconate to 2-(carboxymethyl)-5-oxo-2,5-dihydro-2-furoic acid as part of a sequence which eventually gives ò-ketoadipic acid.
The enzyme carboxy-cis,cis-muconate cyclase gives the isomeric 2-(carboxymethyl)-5-oxo-2,5-dihydro-3-furoic acid as its product.