Molecular and biological characterization of VEGF-mimetic peptidomimetic containing a morpholine β-amino acid

The QK peptide is a 15-residue VEGF-mimetic compound known for its proangiogenic activity. Its helical conformation plays a crucial role in binding to VEGF receptors, activating intracellular signaling pathways in endothelial cells, promoting cell migration, proliferation, and survival. However, peptides composed exclusively by natural amino acids often suffer from poor stability in biological fluids, limiting their therapeutic potential. In this study, we modified the QK sequence shortening the peptide chain by incorporating a non-natural β-amino acid with a morpholine core, that promotes helical secondary structures in model peptides. Structural analysis using CD, FT-IR and NMR revealed that in water, MQK adopts a mixed conformation with partial helical content. Biological characterization on endothelial cells demonstrated that MQK peptidomimetic promotes cell proliferation, survival, migration and invasion providing strong evidence for its pro-angiogenic activity, and a reasonable protease resistance. In definitive, insertion of the morpholine β-amino acid partially destabilizes the helical structure and increases peptide flexibility relative to QK, without impairing biological function. This suggests that the enhanced conformational adaptability of MQK may favor adoption of the bioactive conformation and the interaction with the biological target.