1.D.179. The Hybrid Pyridine-Pyridone Foldamer Channel (HPPFC) Family
Completely abiotic channel systems that concurrently reproduce high selectivity and high permeation rates of natural protein channels are rare. Shen et al. 2022 provided one such biomimetic channel system, i.e., a family of helically folded hybrid amide foldamers, serving as artificial proton channels that mimic key transport features of the exceptionally selective Matrix-2 (M2) proton channel. Possessing an angstrom-scale tubular pore of 3 Å across, these artificial channels transport protons at a rate 22% and 10 times faster than gramicidin A and M2 channels, respectively, with high rejection of water and exceptionally high selectivity factors of 167.6, 122.7 and 81.5 over Cl-, Na+, and K+ ions. The authors proposed a proton transport mechanism where a proton may create its own channel spanning water chain from two or more short water chains to facilitate its own transmembrane flux (Shen et al. 2022).