We present the first examples of atomic-resolution crystal data for the β-peptide 12/10-helix from oligomers of cis-2-aminocyclohexane carboxylic acid (cis-ACHC) with alternating chirality. The local conformations of two enantiomeric cis-ACHC dimer units suggested that a chiral β-peptide may adopt both right-handed and left-handed helical conformations in solution. To probe the conformational behavior of 12/10-helical β-peptides, the two reference helices with a single handedness were synthesized with a more rigidified cis-ACHC derivative. Comparison with these reference helices at low temperature revealed that a chiral cis-ACHC oligomer with alternating chirality indeed displays 12/10-helical conformations with both handedness that equilibrate rapidly in solution. This is a very rare example of chiral oligomers with helix inversion ability. The 12/10-helical backbone should be a valuable addition to potential scaffolds for applications involving helices with dynamic folding propensity.
Bibliographical noteFunding Information:
This study was supported in part by the Basic Science Research Program (NRF-2014R1A1A2053841), the Yonsei University Future-leading Research Initiative of 2015 (2015-22-0132), and the BK21 plus program through the National Research Foundation of Korea. High-field NMR data were acquired at the Korea Basic Science Institute (Western Seoul).
© 2016 American Chemical Society.
All Science Journal Classification (ASJC) codes
- Colloid and Surface Chemistry