Enhancing Aromatic Foldamer Helix Dynamics to Probe Interactions with Protein Surfaces

Abstract

Dynamic helices that undergo exchange between P and M conformations can be used as sensors when their interactions with chiral substances results in a helix handedness bias. For instance, chiral induction in short helically folded aromatic oligoamides based on 8‐amino‐2‐quinoline carboxylic acid (Q) has been used to detect interactions with proteins and nucleic acids. However, the stability of these helices in water increases rapidly with oligomer length to the extent that helix dynamics become too slow for sensing applications. We have developed an approach to enhance the helix dynamics of these oligomers through the introduction of more flexible 6‐aminomethyl‐2‐pyridinecarboxylic acid units (P) while preserving helix integrity. A series of P/Q hybrid oligoamides were synthesized and their rate of helix handedness inversion was evaluated by monitoring induced circular dichroism so as to define the requirements to bring kinetics in a practical range for sequences as long as fourteen units. Proof of principle was then brought by confining such sequences at the surface of carbonic anhydrase and showing that protein‐mediated helix handedness induction occurs.