Site-specific PEGylation at histidine tags

Area of Science:

• Biochemistry
• Protein Engineering
• Pharmacology

Background:

• Protein-based medicines face challenges with rapid clearance from circulation, impacting efficacy and safety.
• Optimizing pharmacokinetics is crucial for successful protein therapeutic development.
• Protein PEGylation is a proven method to extend drug half-life, but site-specific conjugation remains a challenge.

Purpose of the Study:

• To develop and validate a method for site-specific PEGylation of proteins via a polyhistidine tag (His-tag).
• To assess the impact of His-tag PEGylation on protein stability, biological activity, and in vivo pharmacokinetics.

Main Methods:

• Covalent conjugation of polyethylene glycol (PEG) to His-tags on a domain antibody (dAb) and interferon-alpha 2a (IFN).
• Confirmation of PEGylation site using enzymatic digestion, chromatography, and mass spectrometry.
• In vitro stability and activity assays, followed by in vivo pharmacokinetic studies.

Main Results:

• Site-specific PEGylation at the His-tag was successfully achieved for both dAb and IFN.
• PEGylated proteins retained their biological activity and showed enhanced stability.
• In vivo studies demonstrated significantly extended circulation half-lives for His-tag PEGylated proteins.

Conclusions:

• Site-specific, covalent PEG conjugation to a His-tag is a viable strategy for improving protein therapeutic pharmacokinetics.
• This approach maintains protein biological activity and offers a valuable tool for protein drug development.