CD spectra of Trp-containing peptides in the near-UV: a useful tool to assess peptide conformational stability

Angiogenesis is a key target in cancer therapy. With the aim at regulating this process, we recently designed, synthesized and investigated an array of peptides based on the IDNEWRKTQ sequence of the vascular endothelial growth factor (VEGF)-C. The new peptides were optimized to increase both helix stability and binding affinity towards the VEGF receptors. In particular, we exploited the known helix-inducing capabilities of Cα-tetrasubstituted amino acids to stabilize the secondary structure of our peptides. In addition, we inserted Trp residues at appropriate positions as they were expected to enhance the binding affinity.
The conformational preferences of our peptides were investigated by CD and 2D-NMR in aqueous solution. Data analysis confirmed the onset of helical structures. Interestingly, we observed that the absorption bands in the near-UV of the indole (Trp) chromophore constitute a reliable probe to assess the conformational stability of our helical peptides. In this presentation we will correlate this CD feature to the information extracted from the NMR analysis.