Design, optimization and evaluation of specific affinity adsorbent for oligopeptides

A major challenge in the development of affinity adsorbents is the design of specific adsorbents for target molecules. In this paper, a two-step strategy was used to design a specific adsorbent for oligopeptides. Based on the structural characteristics of target peptide DFLAE (DE5), the affinity ligand CDenHis bearing hydrophobic inclusion and electrostatic interaction sites was prepared by grafting histidine onto β-cyclodextrin (CD) using ethylenediamine; ligands with single hydrophobic inclusion or electrostatic interaction sites (CDen and HisOMe) were used as reference ligands. Results indicated that the binding affinity (Ka) of CDenHis with DE5 was 6.23 × 104 M−1, 23- and 61-fold higher than that of CDen and HisOMe, respectively. Computer simulations were used to further optimize the steric configuration of CDenHis. It was found that the optimized ligand CDdnHis exhibited a much improved binding affinity for DE5 (Ka = 1.02 × 105 M−1). Moreover, the corresponding adsorbent A-CDdnHis not only showed much better adsorption ability compared with A-CDenHis, but also excellent adsorption specificity for DE5-containing peptides. Kinetic analysis and adsorption mechanism studies suggested that the configuration matching of CDdnHis with DE5 and the cooperation of multiple interactions led to the fast and selective adsorption of DE5-containing peptides to A-CDdnHis.