Recombinant monoclonal antibodies (mAbs) are a large and rapidly growing category of biological therapeutics. During the manufacturing, distribution, and storage processes, however, mAbs can be exposed to different stress factors, e.g., temperature and pH changes, freezing, thawing, mechanical stress, light exposure, that can potentially result in modifications of the protein and lead to their degradation. Currently, different antibody modifications have been described, e.g., glycosylation, deamidation, and isomerization, C-terminal lysine variant cleavage, N-terminal cyclization, glycation. As a leading antibody-related service provider, Creative Biolabs now offers a comprehensive structural analysis of mAbs to our global clients. Here, we introduce our antibody oxidation analysis service as part of our post-translational modifications (PTMs) analysis services.
Protein oxidation can be triggered during the production process by metal ions and peroxides that are present as impurities, or it can be caused by light. It can happen at nearly all stages of mAb development, such as during cell culture, purification, storage, or even in the process of analytical assays. It has been reported that oxidation mainly occurs at methionine (Met) residues and less frequently at tryptophan (Trp), histidine (His), and other residues.
Fig.1 Oxidation occurs frequently on surface exposed methionines and tryptophans. (Beck, 2013)
Met oxidation occurs primarily at two surface-exposed Fc-residues, Met252 and Met428. It has been reported that oxidation of these two Met residues decreased the thermal stability, protein A binding, FcRn binding, and circulation half-life of IgG1 antibodies. Oxidation of Trp has only been reported in a few cases. For instance, oxidation of a single Trp residue in the complementary-determining region 3 (CDR3) caused a substantial decrease in antigen binding and potency, as reported by Wei et al. (2007). Besides, Li et al. (2014) reported that oxidation of Trp during exposure to light or heat caused changes to the color of mAb products. Moreover, Yang et al. (2014) reported that metal-catalyzed oxidation can lead to oxidative carbonylation of arginine (Arg), proline (Pro), lysine (Lys), and threonine (Thr), especially when those residues are located on the surface of the molecules.
As oxidation of amino acids can induce the structural changes that could potentially impact the biological efficacy, stability, safety, and immunogenicity of mAbs, it is critical to monitor and characterize oxidation during different stages of drug development and manufacturing to ensure product stability and functionality. Based on our mass spectrum-based techniques coupled with chromatographic techniques, Creative Biolabs is capable of offering services including but not limited to:
Moreover, we offer a wide spectrum of antibody function assays to help strengthen your understanding of mAb structure-function relationships. If you are interested in our services, please do not hesitate to contact us for more details.
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