are unable to synthesize the non-essential amino acid asparagine, whereas normal cells are able to make their own asparagine; thus leukemic cells require high amount of asparagine. These leukemic cells depend on circulating asparagine. Asparaginase, however, catalyzes the conversion of L-asparagine to aspartic acid and ammonia. This deprives the leukemic cell of circulating asparagine, which leads to cell death. Enzyme regulation Type I L-asparaginase protein may use the morpheein model of allosteric regulation. History The discovery and development of asparaginase as an anti-cancer drug began in 1953, when scientists first observed that lymphomas in rat and mice regressed after treatment with guinea pig serum. Later it was found out that it is not the serum itself which provoke the tumour regression, but rather the enzyme asparaginase. After researchers comparing different kinds of asparaginases, the one derived from Escherichia coli and Erwinia chrysanthemi turned out to have the best anti-cancer ability. E. coli has thereby become the main source of asparaginase due to the factor that it is also easy to produce in large amount. The pharmacokinetics of asparaginase erwinia chrysanthemi (recombinant) (Rylaze) were evaluated in 225 recipients in study JZP458-201 (NCT04145531), an open-label multicenter trial in which asparaginase erwinia chrysanthemi (recombinant) was administered at various dosages and routes, and the results were used to develop a model to predict serum asparaginase activity at various timepoints. Society and culture Economics Normal asparaginase costs less than its pegylated version, pegaspargase. However, because it doesn't stay as long in the body, the injections need to be more frequent, with the result that total cost of treatment may be lower for the pegylated version. Names Crisantaspase is the British Approved Name (BAN) for asparaginase obtained from Erwinia chrysanthemi. Colaspase is the BAN of asparaginase obtained from Escherichia coli. The United States Adopted Name of crisantaspase is asparaginase Erwinia chrysanthemi. Elspar, Kidrolase, Leunase and Spectrila are brand names for colaspase, while Erwinase and Erwinaze are brand names for crisantaspase. The pegylated version of colaspase is called pegaspargase. Oncaspar is the brand name of pegaspargase. References External links EC 3.5.1 Antineoplastic drugs Orphan drugs World Health Organization essential medicines Wikipedia medicine articles ready to translate