Involved in assimilation of trans-aconitic acid. Preference for cis-aconitic acid is 14-fold higher than for trans-aconitic acid. Not active on intermediates of tricarboxylic acid (TCA) cycle including citric acid, succinic acid, fumaric acid, and 2-oxoglutaric acid or on other dicarboxilic acids including itaconic acid, formic acid, citraconic acid or maleic acid. trans-aconitate = cis-aconitate Activated more than 1.5 fold by Ca(2+), Mg(2+), Mn(2+), Ni(2+), Fe(2+), DDT and 1,10-phenanthroline. Strongly inhibited by Ag(+) and Hg(+). Inhibited by addition of 20% (v/v) glycerol. No effect by addition of NADH or NADPH. kcat and kcat/KM are 4500 sec(-1) and 760 sec(-1) mM(-1), respectively for cis-aconitic acid. kcat and kcat/KM are 15000 sec(-1) and 190 sec(-1) mM(-1), respectively for trans-aconitic acid. Optimum pH is 6.0. Optimum temperature is 37 degrees Celsius. Monomer. May be useful in development of a bioprocess for effective production of trans-aconitic acid.