PEGylation of proteins
Poliethylene glycol (PEG) is a non-immunogenic biological compound made of repeated ethylene glycol units. Covalent and non-covalent attachment to a biological molecule (through the amine group side chains of amino acids) such as proteins and enzymes, called PEGylation, has been shown to increase half-life, reduce immunogenicity, and improve solubility PEG conjugation has the ability to modify physicochemical properties and increase the retention of the therapeutic agents in the body, which are useful for designing newer drug therapies.
AMSbiopharma scientists, have developed the necessary and specific tools for detailed structural characterizations: PEG heterogeneity, site of addition and the number of attached PEGs as is included in ICH Q6B.
For this specific structural characterization of PEGylated proteins a enzymatic digestion followed by HPLC-MS/MS analysis of tryptic peptides of native protein and PEGylated protein allows to locate the PEGytlation sites in a certain fragment.
Furthermore, the ICH Q6B guideline recommended the following methods for the complete characterization of your specific PEGylated proteins:
Due to the possible unwanted reactions happening during protein PEGylation process, special attention must be paid when the following analyses are carried out:
- Disulfide bridges: Possible scrambling take place.
- PTM (glycosylation): Possible modification of glycosylation can take place.
- Process related impurities: Modifications to the protein itself and other impurities may be present.