Creative Biolabs has established a platform to detect a series of post-translational modifications of antibody therapeutics. The amino-acids susceptible to damage by oxidation caused by reactive oxygen species (ROS) are Histidine, Methionine, Cysteine, Tyrosine and Tryptophan. Generally, oxidation is classified into two categories: site-specific metal catalyzed oxidation and non-site specific oxidation.
Methionine and Tryptophan, to a weaker extent, are more susceptible to oxidation in non-site specific reaction. Methionine is dominantly sensitive to free ROS and Tryptophan to light induced oxidation. The extent of sensitivity lies on the solvent accessibility of the side chain and residues buried in the protein core are relatively less sensitive or need longer to react. Antibody oxidation can occur during antibody production, purification, formulation or storage and influence the biological activity and stability.
In the antibody manufacturing process, oxidation is possibly caused by ROS and exposure to light. Therefore, the process conditions must be carefully selected to avoid the risks. The solvent exposed Methionine and Tryptophan should be taken into consideration during the antibody candidate selection to minimize the oxidation potential. When the oxidation at a specific residue cannot be tolerated due to the antibody bioactivity and stability, protein re-engineering needs to be performed. To evaluate the oxidation potential of antibody candidates, Methionine and Tryptophan residues and their surrounding environments are to be detected. Primary amino acid sequence and structural analysis, if available, is combined to determine the degree of susceptibility of these residues to oxidations. Creative Biolabs guarantee that the antibodies are characterized experimentally in house within 4-6 weeks as customer desires.