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Updated: Jul 11, 2026

Electrophoretic Separation of Proteins
Published on: June 12, 2008
Capillary electrophoretic separation of high-molecular-weight poly(ethylene glycol)-modified proteins
Dong Hee Na1, Eun Ji Park, Yeong Woo Jo
1College of Pharmacy, Kyungsung University, 110-1 Daeyeon-dong, Nam-ku, Busan 608-736, South Korea.
Abstract:
This study was designed to demonstrate the utility of capillary electrophoresis (CE) for separating high-molecular-weight poly(ethylene glycol) (PEG)-conjugated proteins. As a CE method, sodium dodecyl sulfate-capillary gel electrophoresis (SDS-CGE) was applied to analyze interferon alpha (IFN) modified with branched and trimer-structured PEG molecules. Five mono-PEG-IFN conjugates prepared with two branched PEGs (MW 20 and 40 kDa) and three trimer-structured PEGs (MW 23.5, 43.5, and 47 kDa) were purified by cation-exchange chromatography and their masses were identified by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. The SDS-CGE method showed high separation capacity by differentiating PEG-IFN conjugates with small differences in molecular size, such as PEG(40K)-, PEG(43.5K)-, and PEG(47K)-IFNs, and it was useful for checking the purity of each mono-PEG-IFN. This study shows that SDS-CGE can well be utilized in the development and quality control of PEGylated proteins prepared with various types of PEG.
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