The enzyme is specific for (2S,3S)-methylcitrate, showing no activity with (2R,3S)-methylcitrate [2]. The enzyme can also use?cis-aconitate as a substrate but more slowly [2]. Both this enzyme and EC?4.2.1.3, aconitate hydratase, are required to complete the isomerization of (2S,3S)-methylcitrate to (2R,3S)-2-methylisocitrate [2].