Exploring the Structural Properties of Positively Charged Peptide Dendrimers.

We report a combined experimental and computational approach to study the structural behavior of positively charged peptide dendrimers. Third-generation dendrimers containing combinations of positive/neutral amino acid residues in the different dendrimer generations were synthesized and their overall size evaluated using diffusion NMR. Molecular dynamics simulations were performed to obtain a comprehensive description of the molecular-level phenomena substantiating the structural differences observed. Comparison of the results presented with previous findings reveals a striking charge-dependent tendency in these systems, where the simple number and placement of charged amino acids in the sequence allows an extensive control over the exhibited structural features. Indeed, we observe that peptide dendrimers bearing progressively higher amounts of charged residues are characterized by an increasing structural plasticity, with a myriad of conformational states equally accessible to them. On the other hand, dendrimers containing only small amounts of charged residues evidence, to some extent, a characteristic structural rigidity.