Purification of PEGylated Proteins

PEGylated protein separations: Challenges and opportunities

“…To facilitate efficient and selective separation of PEGylated proteins, it is essential to consider both (i) the PEGylation reaction, and (ii) the purification process [3]. The PEGylation reaction is complicated and often results in low yields.…”

“…The PEGylation reaction is complicated and often results in low yields. In addition to the target PEGylated protein, the reaction mixture also contains various unwanted species, such as PEGylated isoforms (positional isomers), over PEGylated proteins, the native pro- [3]. However, the separation mechanism is still not fully understood.…”

“…PEGylated proteins behave like much larger molecules than the native protein, as the hydrodynamic size increases due to the attached PEG molecule. So far electrostatic interactionbased chromatography (IEC) is best recommended for the PEGylated protein separation process [3]. It is already known that PEGylated proteins are much more weakly retained in the IEC, and the elution order is basically determined by the ratio between PEG and the protein.…”

“…The low dynamic-binding capacity (DBC) of PEGylated proteins in IEC is another problem [3,7]. This is especially the case when proteins are PEGylated with large PEG.…”

“…Several PEGylated protein drugs, such as PEGylated interferons, are already on the market and others are presently in their clinical trials [1,2]. However, the PEGylation reaction is very product specific so that generalized or platform processes for both reaction and purification have not yet been established [3]. In the current issue of Biotechnology Journal, Günter Allmaier and colleagues, report a modified microchip capillary gel electrophoresis (MCGE), which allows for a rapid separation (one minute) of PEGylated proteins of different degrees of PEGylation [4].…”