Designing of the peptide aptamer

Peptide aptamer consists of two parts: a scaffold protein and a 5–20 residue peptide sequence binding to a particular target. Bacterial Thioredoxin A (UniProt ID {"type":"entrez-protein","attrs":{"text":"P0AA25","term_id":"76363560","term_text":"P0AA25"}}P0AA25 and PDB ID 1KEB) was selected as a scaffold protein. The active site of Thioredoxin A consisting of the sequence CGPC was the point of insertion of the peptide aptamer. The SARS-CoV-2 spike protein binds to ACE2 through the receptor-binding domain. The region of ACE2 involved in binding to the SARS-CoV-2 receptor-binding domain was selected as an aptamer. The aptamer sequence is 18 residues long consisting of the sequence N-AKTFLDKFNHEAEDLFYQ-C and inserted between CGPC motifs of Thioredoxin A.