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Abzena offers a range of technologies for the site-specific conjugation of polyethylene glycol (PEG) or other polymers to therapeutic proteins and peptides. The conjugation of PEG (PEGylation) is a well-established method for extending the half-life and thus duration of action of therapeutic proteins, including antibody fragments.
We provide a range of PEGylation technologies which can be used with different molecular weight PEGs, in linear and branched formats. They have been designed to conjugate PEG to either disulfide bonds, thiols on single cysteines or to poly-histidine motifs.
TheraPEG™ – Disulfide conjugation
TheraPEG™ is a conjugation technology for site-specific PEGylation at solvent-accessible disulfide bonds. Most proteins contain disulfide bonds so there is no need to re-engineer the protein prior to PEGylation.
The TheraPEG™ conjugation process involves disulfide bond reduction prior to conjugation but unlike conjugation using maleimide chemistry the bond is re-bridged as part of the conjugation process thereby restoring the tertiary structure of the protein. Site-specific conjugation using TheraPEG™ reduces the heterogeneity of the conjugate, produces a stable product and, because the conjugation process is efficient and predictable, minimises reagent use.
HiPEG™ – Histidine conjugation
HiPEG™ is a conjugation technology for site-specific PEGylation at histidine sequences expressed within or at the N or C terminal ends of a protein. Conjugation at the terminus of the protein can have the advantage of reducing the shielding effect of the PEG on the functional part of the protein thereby minimising the effect on its activity. A histidine tag added to the terminus of a protein to facilitate purification can be used as the conjugation site without interfering with its use for purification of the conjugate.
HiPEG™ has been used to conjugate branched, single and multiple linear PEG molecules to a diverse range of therapeutic proteins, including cytokines antibody fragments and an increase in half-life in vivo has been demonstrated for these examples.
CyPEG™ – Cysteine conjugation
CyPEG™ is a conjugation technology for site-specific PEGylation at a thiol side-chain on a free cysteine. The thiol residue on a cysteine readily undergoes selective and efficient conjugation. CyPEG™ can be used over a wide pH range and results in a more stable conjugate than can be produced using maleimide conjugation chemistry. Proteins or peptides that do not have a cysteine can be engineered to provide a site for site-specific conjugation using CyPEG™.