This domain is found at the C terminus of adenylosuccinate lyase (ASL; PurB in Escherichia coli). It has been identified in bacteria, eukaryotes and archaea and is found together with the lyase domain . ASL catalyses the cleavage of succinylaminoimidazole carboxamide ribotide to aminoimidazole carboxamide ribotide and fumarate and the cleavage of adenylosuccinate to adenylate and fumarate [].
Argininosuccinate lyase (ASL or ASAL, ) participates in arginine synthesis in all organisms catalysing the reversible breakdown of argininosuccinate to arginine and fumarate. The reaction is also part of the urea cycle []. The crystal structures of ASLs from several species have been studied, in particular the duck delta1 and delta2 eye lens crystallins, which are inactive and active homologues of ASL, respectively []. ASL is a member of the Lyase class I family, these proteins are active as tetramers. The four active sites of the homotetrameric enzyme are each formed by residues from three different subunits. In humans, mutations in ASAL result in the autosomal recessive disorder argininosuccinic aciduria [].This entry represents argininosuccinate lyase and includes avian delta crystallins whose biological role is to provide the optically clear cellular protein of the eye lens.