Amino Acid Substitution

Fc-based therapeutics, including monoclonal antibodies (mAbs) and Fc-fusion proteins, are growing fast in the pharmaceutical industry. The Fc fragments of these Fc-based drugs are critical to their functioning and have been the focus of many engineering efforts. As a pioneer company of antibody service provider, Creative Biolabs now offers Fc engineering services using different methods, such as site mutagenesis on certain positions by amino acid substitution. We provide high-quality services to meet the specific needs of our clients at competitive prices.

Amino Acid Substitution

Recombinant mAbs have been used in multiple therapeutic applications and their efficacy attributes to both the antigen-binding fragment and Fc. Fc, which naturally exists in mAbs, can also function as the skeleton in Fc-fusion proteins. These Fc-fusion proteins have been used as research tools for many applications and hold promise as therapeutics. Due to the fact that the Fc fragment plays a vital role in effector functions, product half-life, and druggability, Fc-engineering technologies have been widely investigated to optimize drug performance. One of the major technologies is the amino acid substitution at the antibody Fc region, which has been used to enhance antibody cytotoxic activities such as antibody-dependent cellular cytotoxicity (ADCC) and complement-dependent cytotoxicity (CDC).

Exchanging amino acids directly in the FcγR binding site within the antibody’s Fc domain is a logical strategy to manipulate the Fc/FcR interaction. Researchers have identified two sites in a human IgG, E333 and K326, which, when substituted, have a significant effect on the biological activity of the antibody. Amino acid substitutions at these two sites in a human IgG increased or rescued C1q binding and CDC activity.

Besides, combinational strategies focused on introducing amino acid exchanges in the protein backbone and modifying the Fc-bound glycosylation profile have been described. For instance, Researchers generated anti-CD20 mAbs with amino acid substitutions using transgenic silkworms and analyzed their biological activities to assess the effect of the combination of amino acid substitutions and glycoengineering on the Fc-mediated function of mAbs. Several types of amino acid substitutions at the Fc region modified the Fc-mediated biological activities of silkworm or CHO-derived mAbs, resulting in the generation of Fc-engineered mAbs with characteristic Fc-mediated functions. The combination of amino acid substitutions at the Fc region and glycoengineering using transgenic silkworm makes it possible to generate Fc-engineered mAbs with suitable Fc-mediated biological functions.

Fig.1 The potential substitution existing in the ABL1 protein’ amino acid sequence.¹

Based on the creative skills of our highly qualified scientists, Creative Biolabs strives to provide the best high-quality protein engineering services to contribute to the success of your project. Besides amino acid substitution, Creative Biolabs also provides other types of Fc engineering approaches such as exchanging larger amino acid stretches between different isotypes and display-based technology to obtain optimized variants. If you are interested in the service we provide, please feel free to contact us for more detailed information.

Reference

1. Zhuravleva, Svetlana I., et al. "Prediction of Amino Acid Substitutions in ABL1 Protein Leading to Tumor Drug Resistance Based on “Structure-Property” Relationship Classification Models." Life 13.9 (2023): 1807.
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