This superfamily represents the N-terminal of the enolase and similar structural domains found in several enzymes, such as D-glucarate dehydratases, muconate-lactonizing enzymes, mandelate racemases, d-galactonate dehydratase, O-succinylbenzoate synthases and chlormuconate cycloisomerases, l-Ala-d/l-Glu epimerases, 3-methylaspartate ammonia lyase, etc. These enzymes share a bidomain structure containing a capping domain and a C-terminal barrel domain. The N-terminal domain forms part of the capping domain.