title: Modification of a reactive cysteine explains differences between rasburicase and Uricozyme, a natural Aspergillus flavus uricase.
abstract: Urate oxidase is used in humans for the control of uric acid in patients receiving chemotherapy. Rasburicase (Fasturtec/Elitek), a recombinant urate oxidase expressed in Saccharomyces cerevisiae, was compared with Uricozyme, the natural enzyme produced by Aspergillus flavus. Rasburicase has a higher purity as demonstrated by SDS/PAGE and chromatographic analysis and a better specific activity. The differences observed for Uricozyme are likely attributable to the previously used purification process, which modifies the enzyme. The production process of rasburicase, on the other hand, preserves the structure of the molecule. MS analysis shows that Uricozyme contains a cysteine adduct on Cys(103). In the crystal structure, the sulphur atom of the cysteine residue in position 103 is orientated to the external surface of the tetramer, whereas the sulphur atom of two other cysteine residues (Cys(35) and Cys(290)) is orientated to the centre of the canal formed by the tetramer. The same adduct is produced by simple incubation of the rasburicase with cysteine.
authors.affiliation: Analysis and Quality Control Unit, Sanofi-Synthelabo Recherche, Innopole, Voie no. 1, BP 137, 31676 Labège Cédex, France. alain.bayol@sanofi-synthelabo.com
authors.forename: Alain
authors.initials: A
authors.lastname: Bayol
authors.forename: Joël
authors.initials: J
authors.lastname: Capdevielle
authors.forename: Pascal
authors.initials: P
authors.lastname: Malazzi
authors.forename: Armelle
authors.initials: A
authors.lastname: Buzy
authors.forename: Marie
authors.initials: M
authors.lastname: Claude Bonnet
authors.forename: Nathalie
authors.initials: N
authors.lastname: Colloc'h
authors.forename: Jean-Paul
authors.initials: JP
authors.lastname: Mornon
authors.forename: Denis
authors.initials: D
authors.lastname: Loyaux
authors.forename: Pascual
authors.initials: P
authors.lastname: Ferrara
mesh_terms: D001231:Aspergillus flavus / Q000201:enzymology; D003545:Cysteine / Q000737:chemistry*; D004789:Enzyme Activation; D011786:Quality Control; D011994:Recombinant Proteins / Q000032:analysis; D012441:Saccharomyces cerevisiae / Q000201:enzymology / Q000235:genetics; D014503:Urate Oxidase / Q000737:chemistry* / Q000648:ultrastructure*
chemical_list: D011994:Recombinant Proteins; D014503:Urate Oxidase; D003545:Cysteine