BEYOND MIDAS: DISCOVERY OF A SPECIFIC NON-CANONICAL C16 PEPTIDE BINDING SITE IN ⍺Vβ3 INTEGRIN

Integrins αvβ3 and α5β1 are key mediators of cell adhesion, angiogenesis, and tumor progression, making them important therapeutic targets. Although the
laminin-derived C16 peptide has been reported to interact with both receptors, the molecular basis underlying its binding selectivity remains poorly understood. In this study, we employed an integrated computational workflow combining ADMET prediction, molecular docking, and all-atom molecular dynamics simulations to
investigate the pharmacokinetic profile and binding behavior of C16 toward αvβ3 and α5β1 integrins.The predicted pharmacokinetic properties indicate that C16 exhibits limited oral bioavailability but favorable binding characteristics and moderate metabolic stability. Docking analyses showed that C16 interacts with the canonical MIDAS region in both integrins through conserved hydrogen-bonding and hydrophobic interactions. In addition, a previously unrecognized binding pocket was identified exclusively in αvβ3, positioned opposite the MIDAS site. This putative noncanonical site forms an amphiphilic interface capable of stabilizing peptide
binding through complementary electrostatic and hydrophobic interactions.Molecular dynamics simulations further demonstrated that peptide binding at this alternative site is structurally stable and associated with reduced conformational fluctuations and more favorable binding free energies compared with the canonical interaction. These findings suggest that αvβ3 may recognize C16 through an additional binding mode not observed in α5β1, providing a plausible molecular explanation for subtype selectivity. Overall, this work proposes a new computational model for C16–αvβ3 recognition and highlights a potential noncanonical binding site that may support the rational design of selective peptide-based ligands targeting integrin-mediated angiogenesis and cancer progression.