Identification of a methotrexate-binding peptide from a T7 phage display screen using a QCM device

An 11-mer unique peptide sequence SIFPLCNSGAL was identified as a methotrexate (MTX)-binding peptide from a T7 phage display screen using a quartz-crystal microbalance (QCM) biosensor. The synthetic peptide displayed weak interaction with MTX (KD 2.23 × 10−5 M) using surface plasmon resonance (SPR). Interestingly, analysis of the primary amino acid sequence of the peptide identified similarities to the MTX-binding site of dihydrofolate reductase (DHFR). Our results highlight the importance of this primary sequence for the recognition of the MTX molecule.