Two related families of asparaginase are designated type I and type II according to the terminology in E. coli, which has both: L-asparaginase I is a low-affinity enzyme found in the cytoplasm, while L-asparaginase II is a high-affinity secreted enzyme synthesized with a cleavable signal sequence. This model describes L-asparaginases related to type I of E. coli. Archaeal putative asparaginases are of this type but contain an extra ~ 80 residues in a conserved N-terminal region. These archaeal homologs are included in this model.