Custom PEGylation Service

Creative Biolabs offers first class custom PEGylation services that are based on next-generation PEGylation technologies.

PEGylation is the process of covalently attaching one or more chains of PEG [Poly(ethylene glycol)], also known as poly(ethylene oxide) (PEO) or polyoxyethylene (POE)], to a protein molecule, thus creating a PEG-conjugated protein. Therapeutic proteins are either rapidly degraded, have a short circulating life, or are rapidly excreted when introduced into the bloodstream. Consequently, many protein-based biopharmaceuticals require repeated intravenous infusions for therapeutic efficacy. Also, repeated injections of a protein-based biopharmaceutical can result in adverse immunological responses and side effects. As the single proven solution to all these problems, PEGylation has become the biopharmaceutical delivery technology of choice for intravenously administered therapeutic proteins. Covalent attachment of PEG to a therapeutic protein can "mask" the protein from the host's immune system (thus, reduce immunogenicity and antigenicity), and increase the hydrodynamic size (size in solution) of the agent, which prolongs its circulatory time by reducing renal clearance. These benefits allow significantly less protein (as compared with the un-PEGylated protein) to be administered and yet achieve the same desired therapeutic effect. In addition, a reduction in the amount of protein used in each dose results in lower raw material and production costs. For these reasons, PEGylation becomes mandatory to think about when developing a biopharmaceutical drug. To Date, more than ten PEGylated protein drugs have been approved by FDA and another tens of PEGylated proteins are in clinical trails.

The first generation PEG conjugates are usually prepared by random PEGylation of N-terminal NH2 group and Lysine residues. Although most PEGylated drugs currently on market were developed by using these methods, the overall utility of these methods are limited due to the heterogeneity and decreased bioactivity of the products. Even after extensive optimization, the coupling reactions commonly result in multiple PEGylated isoforms with non-uniform chemical and pharmaceutical properties. Therefore, homogeneous PEGylation of proteins is important for developing safer protein drugs. To meet these needs, we have developed novel site-specific PEGylation technologies that include:

1. N-terminal specific PEGylation

We have developed N-terminal specific PEGylation to conjugate reactive PEG derivatives to proteins. Proprietary methods are developed to couple N-Hydroxysuccinimide and propionaldehyde PEG derivatives to proteins, leading to the selective or preferential N-terminal PEGylation of the protein.

2. Thiol-selective PEGylation

We employ maleimide- and haloacetate-based PEG derivatives to PEGylate cysteine residues present in a protein or introduced into the protein by site-directed mutagenesis. This method is particularly important for peptides, since the surface area of a peptide is much smaller than that of a larger biologics, on which the 1st generation PEGylation approaches can not be used.

3. Enzymatic PEGylation

Enzymatic PEGylation is another next-generation PEGylation technology we have established, in which an enzymatic method is used for covalent binding of PEG moieties to pharmaceutical proteins. In this technology, we use transglutaminase (TGase) to selectively attack only one or few specific amino acids on the protein, enabling site -specific PEGylation.

We have extensive experience in PEGylation of peptides, recombinant proteins, and antibody fragments. However, we are aware that each drug candidate is different and there is no standardized PEGylation protocol. Depending on the desired pharmacokinetics properties and biological activities to be maintained for a therapeutic protein, a proper PEG reagent, a good reaction group and a right reaction must be investigated and used. Frequently, small scale PEGylation reactions are screened together with appropriate bio-functional assays to optimize a PEGylation protocol for a particular biologics.

In addition to the custom PEGylated proteins we developed, a large number of PEGylated proteins produced in house are marketed by our catalogue protein division Creative BioMart. Also, a comprehensive menu of PEGylation reagents including branched PEG derivatives, Methoxy-PEG derivatives, homobifunctional PEG Derivatives, heterobifunctional PEG Derivatives, and multi-arm PEG derivatives as well as custom PEG derivatives and PEG raw materials are available at our chemistry division, BOC Sciences.