Redox investigation of L-A9 peptide and evaluation of its binding with double stranded DNA

L-A9 is one of the important short peptides having biomedical applications in relation to its affinity towards HER2 receptors. The peptide has been synthesised using manual solid phase synthesis protocol and the redox property has been investigated using the voltammetric techniques. The oxidation peak of the peptide has shown strong pH dependency, revealed the 1 e and 2 proton transfer process. Electroanalytical method is developed with limit of detection of 1.17 × 10^-7 M. The modulation of the redox property has been monitored to investigate the binding of the peptide with dsDNA, with binding constant of 1.8 × 10⁵ M^{- 1}. Spectroscopic measurements of the peptide revealed the pH dependent electronic transition and the binding constant with dsDNA of 1.4 × 10⁴ M^{- 1}. The needle like assembly of L-A9 peptide has been indicated from the SEM measurements with coil kind of morphology of dsDNA has been observed when the L-A9 peptide and dsDNA interacted with each other. The electrochemical and spectroscopic investigations indicated that the acidic functional groups of L-A9 interacts with the major groove of dsDNA through the modifications of 3 hydrogen bonds between the strands, whereas the basic functional groups of L-A9 binds externally with dsDNA by formation of bonds with O atoms of the phosphodiester groups, which has been supported from the molecular docking investigations.