1.D.177. The Peptide-appended Pillararene (PAPA) Family
Peptide-appended pillararenes (PAPA) with an angstrom-scale pore size (∼4.5 Å) catalyze water transport owing to their conformational flexibility and high permeability. Water transport characteristics of this unique class of biomimetic pores in different membrane environments need to be described. Barden and Vashisth 2021 presented an inception-to-implementation description of the water dynamics triggered by PAPA in biological (lipid) and biomimetic (block copolymer) membranes by using molecular dynamics simulations. Simulations revealed significant conformational flexibility in regions of the peptide arms away from the central rigid PAP ring and its adjacent regions, and showed that insertion of PAPA channels is more favorable in lipids than in biomimetic membranes. Further, PAPA channels preserve single channel permeabilities of low free energy barriers in each type of membrane, and the number of internal H-bonding sites can be nicely correlated to single file water diffusivity. These simulation results are in great accord with other synthetic and biological water channels having sub-nm pore sizes.