title: Stabilization of L-asparaginase modified with comb-shaped poly(ethylene glycol) derivatives, in vivo and in vitro.
abstract: L-Asparaginase from Escherichia coli was coupled with two types of comb-shaped copolymer of poly-(ethylene glycol) derivative and maleic anhydride (activated PM), having molecular weights of 13,000 and 100,000 (activated PM13 and PM100, respectively) with multivalent reaction sites. After single intravenous injections of PM100-asparaginase and nonmodified asparaginase into rats, the enzymic activity of PM100-asparaginase in serum was well retained for at least 11 days, and the serum L-asparagine concentration remained undetectable for 27 days. The half-lives of PM100-asparaginase and nonmodified asparaginase were 50 and 1.5 h, respectively. Stabilization of L-asparaginase toward heat, urea, and acidity was caused by modifying the enzyme with activated PM13 and PM100. Especially, PM100-asparaginase retained high enzymic activity toward heat and urea, compared with PM13-asparaginase. It was suggested that these modifiers with a comb-shaped form and with multivalent reactive sites cover the whole surface of the asparaginase molecule and stabilize its conformation possibly through multiple covalent bindings and through various noncovalent interactions.
authors.affiliation: Department of Materials Science and Technology, Toin University of Yokohama, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Kodera
authors.forename: T
authors.initials: T
authors.lastname: Sekine
authors.forename: T
authors.initials: T
authors.lastname: Yasukohchi
authors.forename: Y
authors.initials: Y
authors.lastname: Kiriu
authors.forename: M
authors.initials: M
authors.lastname: Hiroto
authors.forename: A
authors.initials: A
authors.lastname: Matsushima
authors.forename: Y
authors.initials: Y
authors.lastname: Inada
mesh_terms: D000818:Animals; D001215:Asparaginase / Q000737:chemistry* / Q000493:pharmacokinetics / Q000494:pharmacology; D004795:Enzyme Stability; D004926:Escherichia coli / Q000201:enzymology; D006207:Half-Life; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D008299:Maleic Anhydrides / Q000737:chemistry; D008968:Molecular Conformation; D011092:Polyethylene Glycols / Q000737:chemistry*; D051381:Rats; D013499:Surface Properties; D014508:Urea / Q000737:chemistry
chemical_list: D008299:Maleic Anhydrides; D011092:Polyethylene Glycols; D014508:Urea; D001215:Asparaginase