H2O + L-asparagine = L-aspartate + NH4(+) Homotetramer. By cAMP and anaerobiosis. Available under the names Crastinin (Bayer), Elspar (Merck), Kidrolase (Rhone-Poulenc) and Leunase (Kyowa). Also available as a PEG-conjugated form (Pegaspargase) under the name Oncaspar (Enzon). Used as an antineoplastic in chemotherapy. Reduces the quantity of asparagine available to cancer cells. E.coli contains two L-asparaginase isoenzymes: L-asparaginase I, a low-affinity enzyme located in the cytoplasm, and L-asparaginase II, a high-affinity secreted enzyme. Belongs to the asparaginase 1 family.