Tina Rahnama - Department of Biology, Faculty of Science, Yazd University, Yazd, Iran
Mehri Khatami - Department of Biology, Faculty of Science, Yazd University, Yazd, Iran
Mohammad Mehdi Heidari - Department of Biology, Faculty of Science, Yazd University, Yazd, Iran
Reyhane Chamani - Department of Biology, Faculty of Science, Yazd University, Yazd, Iran

Backgrounds: Antibodies are glycoproteins that bind specifically to their antigen with highaffinity and cause the destruction of cancer cells and therefore have many applications intherapy. High expression of CD۲۰ in leukemia and lymphomas and having extracellular epitopesdetected with different antibodies make these proteins a suitable target for immunotherapy withmonoclonal antibodies. The aim of this study was to target mutagenesis in CDR۳ of Anti-CD۲۰antibody to produce optimal antibody in the diagnosis and treatment of leukemia.Materials and Methods: Tyr ۱۰۷ in the antibody was mutated to Arg using PyMOL software.Then, the native and the mutant antibody were docked to CD۲۰ using HADDOCK server.Binding residues had been analyzed by PyMOL. Docking tools were used to investigate thetendency of the complex antibody-CD۲۰ to bond better.Results: Haddock Z-score were -۷۷.۶ and -۷۷.۸ for the native and mutant, respectively.Electrostatic energy for the complex of antibody-CD۲۰ was -۱۰۵.۵ in the mutant compared to -۲۳۴.۲ for the native.Conclusion: We can conclude that mutation of a nonpolar amino acid to a polar and chargedOne, improved the interaction of antibody to the CD۲۰ antigen. So, it is worth to furtherinvestigate the application of this engineered antibody in the treatment and diagnosis of cancer.

Antibody optimization, CDR۳, Docking, Site-directed mutation