Monoclonal antibodies allow specific antigen binding, which is why they are used in a wide range of applications. Monoclonal antibodies are currently isolated and purified mainly by using protein A-based affinity chromatography, which, despite its high binding selectivity, has a number of disadvantages. As a result, efforts are being made to develop alternative ligands that are more cost-efficient and stable. In this master's thesis, we designed new linear and cyclic peptide variants based on the starting peptide obtained in previous research and the results of enrichment during library screening. The goal was to identify peptide ligands with improved binding affinity for the Fc IgG region. The designed peptides were presented on a bacteriophage and their binding affinities were comparatively evaluated with ELISA assays. The results of cyclic variants were contradictory, so cyclic variants were not pursued further. The linear variants were subjected to a series of ELISA assays during which the peptides were gradually excluded. The GSYWYNVWF peptide was determined to have optimal binding affinity. Peptide selection was confirmed by one-way ANOVA assay, which showed statistically significant differences in binding affinity between the selected peptide and other variants. We performed a bioinformatical analysis (i.e., calculation of theoretical isoelectric point, GRAVY and instability indices), which gave a possible explanation of the reasons for the binding differences among the peptides.
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