title: Quantitatively investigating monomethoxypolyethylene glycol modification of protein by capillary electrophoresis.
abstract: Capillary electrophoresis (CE) was applied to study quantitatively protein modification with succinimidyl succinate-activated monomethoxypolyethylene glycol (MPEG-SS). The heterogeneous distribution of modified proteins and the average modification degree were determined by CE, and the latter met with the results from 2,4,6-trinitrobenzenesulfonic acid (TNBS) spectrometric assay. It was found that the optimal buffer pH for the modification was between pH 7.4 and 8.4, and the modification degree decreased when the modified sample was preserved in high pH solutions. The protein fractions attached with different number of polyethylene glycols (PEGs) were monitored along the process of protein modification. CE was proved to be efficient to evaluate quantitatively several factors of the protein modification, including the modifier/protein molar ratio, the stability of conjugates in different pH environments, and the time course of modification process.
authors.affiliation: State Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, P.O. Box 353, Beijing 100080, PR China. weijun@itsa.ucsf.edu
authors.forename: Weijun
authors.initials: W
authors.lastname: Li
authors.forename: Zhiguo
authors.initials: Z
authors.lastname: Su
mesh_terms: D000818:Animals; D002417:Cattle; D002626:Chemistry, Pharmaceutical / Q000379:methods; D019075:Electrophoresis, Capillary / Q000379:methods*; D006863:Hydrogen-Ion Concentration; D011092:Polyethylene Glycols / Q000737:chemistry*; D011506:Proteins / Q000032:analysis / Q000737:chemistry / Q000302:isolation & purification; D012259:Ribonuclease, Pancreatic / Q000032:analysis / Q000737:chemistry* / Q000302:isolation & purification
chemical_list: D011506:Proteins; D011092:Polyethylene Glycols; C028210:monomethoxypolyethylene glycol; D012259:Ribonuclease, Pancreatic