E-mail: monika. Incorporation of a trans - 1 S ,2 S aminocyclopentanecarboxylic acid residue into the outer positions of the model coiled-coil peptide led to the formation of helical foldamers, which was determined by circular dichroism CD and vibrational spectroscopy. The oligomerization state of the obtained peptides in water was established by analytical ultracentrifugation AUC.
Previously, we proposed an approach for the rational construction of helix-containing nanofibers using the modification of the outer positions of the coiled-coil structure with helix-promoting trans -aminocyclopentanecarboxylic acid trans -ACPC.
This methodology was probed in two sets of peptides with oligomerization states different from the oligomerization states in our previous studies. The oligomerization state of the obtained peptides was established by analytical ultracentrifugation AUC. The aggregation behavior of the obtained peptides was followed by a thioflavin T ThT test and Congo red staining. The final nanostructures were characterized using atomic force microscopy AFM and transmission electron microscopy TEM.
Comparison of the results for three sets of peptides gave a broader view of the hierarchical approach and revealed some very interesting features for specific groups of peptides and structural polymorphism. In the next design step, the sequences of model peptides 1 and 2 were subjected to further modifications. Subsequently, the designed peptides were synthesized using solid-phase peptide synthesis SPPS and purified with high-performance liquid chromatography HPLC.
Next, the influence of this structurally constrained residue on the conformational behavior and stability of the helical structures as well as on nanostructure formation was evaluated. The model coiled-coil peptides and the peptides modified with trans -ACPC were then subjected to sedimentation velocity analytical ultracentrifugation SV-AUC to provide new data on sample composition and collect information on the molecular weights and sedimentation coefficients of the observed species as well as on the effect of unnatural amino acid incorporation on sample heterogeneity.
