Design of aptamer peptides for immunomodulation.

In this study, we describe the design of peptide aptamers to modulate interactions between CD2 and CD58 (co-stimulatory molecules) in the immune response. We designed peptide aptamers based on the sunflower trypsin inhibitor-1 (SFTI-1) template, incorporating functional groups that confer conformational stability and aqueous solubility. To address the challenges posed by conformational isomerism in the sunflower trypsin inhibitor template due to proline-proline sequences in peptide design, we developed two aptamer peptides, SFTI-FGUA and SFTI-DMY, incorporating specific functional groups. SFTI-FGUA features a side-chain guanidine group on phenylalanine, while SFTI-DMY features a dimethyl group at the meta position relative to tyrosine's hydroxyl group. These bulky substitutions on the phenyl ring effectively restrict conformational flexibility and enhance solubility. Evaluation of these peptides using cell adhesion inhibition assays revealed that both aptamer peptides not only exhibited significant inhibition of cell adhesion but also exhibited a predominant conformation in solution. Furthermore, these peptides exhibited stability against enzymatic degradation.