title: The chemical modification of E. coli L-asparaginase by N,O-carboxymethyl chitosan.
abstract: E. coli L-asparaginase was modified with N,O-carboxymethyl chitosan in the presence of normal product L-aspartic acid, which protected the active site of the enzyme. The modified enzyme remained high catalytic activity, showed greater stability against trypsin and alpha-chymotrypsin, but lost its activity more rapidly at high temperature (> 45 degrees C) than did the native enzyme. When tested in vivo, the plasma half-life of the modified enzyme (t1/2 = 40 hr) was over 33 times longer than that of the native enzyme (t1/2 = 1.6 hr). The results showed that the modified L-asparaginase may be much more useful than did the native enzyme for clinical treatments of tumors.
authors.affiliation: State Key Laboratory of Functional Polymers for Adsorption and Separation, Institute of Polymer Chemistry, Nankai University, Tianjin, P.R. China.
authors.forename: G
authors.initials: G
authors.lastname: Qian
authors.forename: J
authors.initials: J
authors.lastname: Zhou
authors.forename: J
authors.initials: J
authors.lastname: Ma
authors.forename: D
authors.initials: D
authors.lastname: Wang
authors.forename: B
authors.initials: B
authors.lastname: He
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000737:chemistry / Q000493:pharmacokinetics*; D001215:Asparaginase / Q000737:chemistry / Q000378:metabolism / Q000493:pharmacokinetics*; D002686:Chitin / Q000031:analogs & derivatives* / Q000737:chemistry / Q000493:pharmacokinetics; D048271:Chitosan; D004355:Drug Stability; D004795:Enzyme Stability; D004926:Escherichia coli / Q000201:enzymology; D006207:Half-Life; D008657:Metabolic Clearance Rate; D011817:Rabbits
chemical_list: D000970:Antineoplastic Agents; C077199:O,N-carboxymethylchitosan; D002686:Chitin; D048271:Chitosan; D001215:Asparaginase