PEG refers to polyethylene glycol, which typically exists in the form of long polymer chains. Simultaneously hydrophilic and lipophilic, water soluble, and nontoxic, PEG is synthesized from chains of ethylene oxide, which can branch or stretch to any length. Typically, PEG is linked to a protein or peptide through reactive molecular groups on amino acid side chains, most often lysine.
PEGylation is the process of both covalent and non-covalent attachment or amalgamation of polyethylene glycol polymer chains to molecules and macrostructures, such as a drug, therapeutic protein or vesicle. PEGylation is routinely achieved by the incubation of a reactive derivative of PEG with the target molecule. The covalent attachment of PEG to a drug or therapeutic protein can "mask" the agent from the host's immune system, and increase its hydrodynamic size (size in solution), which prolongs its circulatory time by reducing renal clearance. PEGylation can also provide water solubility to hydrophobic drugs and proteins.
Figure 1.The general strategy for protein PEGylation. (Jonathan, K, Dozier. 2015)
As a bio-compatible material, PEG-protein conjugates are nontoxic, non-immunogenic, non-antigenic, highly soluble in water and approved by FDA for human usage. Compared with the original “naked” protein therapeutics, the PEG-drug conjugates have several improvements:
Protein PEGylation at Creative Proteomics
There are at least three aspects to the detection and analysis of PEGylated proteins, including the average degree of protein modification, the degree of modification of PEG-modified sites and specific sites, and the relative content of proteins with different degrees of modification. At Creative Proteomics, we have developed a professional platform for protein PEGylation analysis, which contains various techniques, including but not limited to:
PEGylation now plays an important role in drug delivery to enhance the potentials of peptides and proteins as therapeutic agents. Creative Proteomics provides sophisticated analytical techniques to help you characterize protein PEGylation at specific sites. If you have any questions or specific needs, please don’t hesitate to contact us.
1. Chun, Zhang.; et al. Site-Specific PEGylation of Therapeutic Proteins via Optimization of Both Accessible Reactive Amino Acid Residues and PEG Derivatives. BioDrugs. 2012, 26(4) 209–215.
2. Jonathan, K, Dozier; Mark, D.,Distefano. Site-Specific PEGylation of Therapeutic Proteins. Int J Mol Sci. 2015, 16(10): 25831–25864.