1st International and 10th National Iranian Conference on Bioinformatics
Home Accepted Papers
Evaluation of site-directed mutagenesis on stability and affinity of Bevacizumab antibody
Paper ID : 1403-ICB10
Authors:
Shima Mirhoseini, Mahsa Mirzaei *, Mohammad Mehdi Heidari, Mehri Khatami
Department of Biology, Faculty of Sciences, Yazd University, Yazd, Iran
Abstract:
Bevacizumab is an anti-angiogenesis monoclonal antibody which prevents the interaction of VEGF-A with VEGFR and thereby inhibits the activation of VEGF signaling pathways that promote neovascularization [1]. The type of amino acids at the site of antigen and CDR interaction is important and also the amino acid diversity is accumulated in the three complementarity determining regions (CDRs). Cysteine, proline and methionine are avoided for their chemical reactivity or constraints in folding. Isoleucine and leucine are underrepresented to decrease the surface hydrophobicity. Furthermore, arginine, lysine, serine, threonine, tyrosine and asparagine are preferred as these amino acids occur frequently in the paratope, where they are involved in antigen interaction [2]. As a result, these substitutions enable us to optimize antibodies’ affinity and stability. VEGF-A amino acid sequence and Bevacizumab amino acid sequence was also extracted from https://www.rcsb.org with 6BFT PDB code [3]. This web server was also used for CDR prediction. Initialy we used pymol software to visualize antibody-epitope interaction. Some amino acids were selected as significant residues in Bevacizumab structure by employing the results of different software. These residues located in one of the three CDR regions. Pymol software can predict amino acid substitution influence on antibodies’ affinity by measuring bond length and strength. In order to explore the effect of amino acid substitution on antibodies’ stability mCSM web server also was used. Several characteristics of monoclonal antibody should be developed in order to use them as therapeutic agents, including biding affinity, folding stability and pharmacokinetics. Optimization strategies for monoclonal antibody provide the possibility of modification and improvement of an antibody molecule. By analysis with mCSM some of mutants of antibody improved stability, especially conversion of tyrosine 102 to glutamic acid. Evaluation of optimization for antibody affinity by Pymol software indicated that the conversion of tryptophan 108 to arginine improved affinity.
Keywords:
Site-directed mutagenesis; Stability; Affinity; Bevacizumab antibody
Status : Paper Accepted (Poster Presentation)