Different transport behaviors of NH4 (+) and NH3 in transmembrane cyclic peptide nanotubes.
Two water-filled transmembrane cyclic peptide nanotubes (CPNTs) of 8×cyclo-(WL)n=4,5/POPE were chosen to investigate the dependences of the transport properties of the positive NH4 (+) and neutral NH3 on the channel radius. Molecular dynamic simulations revealed that molecular charge, size, ability to form H-bonds and channel radius all significantly influence the behaviors of NH4 (+) and NH3 in a CPNT. Higher electrostatic interactions, more H-bonds, and water-bridges were found in the NH4 (+) system, resulting in NH4 (+) meeting higher energy barriers, while NH3 can enter, exit and permeate the channels effortlessly. This work sheds a first light on the differences between the mechanisms of NH4 (+) and NH3 moving in a CPNT at an atomic level. Graphical Abstract Snapshot of the simulation system of NH4 (+)_octa-CPNT with an NH4 (+) initially positioned at one mouth of the tube, PMF profiles for single NH4 (+) ion and NH3 molecule moving through water-filled transmembrane CPNTs of 8×cyclo-(WL)n=4,5/POPE and sketch graphs of the possible H-bond forms of NH3 and NH4 (+) with the neighboring water.
College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou, 215123, People's Republic of China.
Mingming
M
Zhang
College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou, 215123, People's Republic of China. jffan@suda.edu.cn.
Jianfen
J
Fan
College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou, 215123, People's Republic of China.
Jian
J
Xu
College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou, 215123, People's Republic of China.
Peipei
P
Weng
College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou, 215123, People's Republic of China.
Huifang
H
Lin
D000641:Ammonia / Q000737:chemistry*; D064751:Ammonium Compounds / Q000737:chemistry*; D004058:Diffusion; D006860:Hydrogen Bonding; D056004:Molecular Dynamics Simulation; D045333:Nanotubes, Peptide / Q000737:chemistry*; D010456:Peptides, Cyclic / Q000737:chemistry*; D055672:Static Electricity; D014867:Water / Q000737:chemistry
D064751:Ammonium Compounds; D045333:Nanotubes, Peptide; D010456:Peptides, Cyclic; D014867:Water; D000641:Ammonia
Cyclic peptide nanotubes; Molecular dynamics simulations; NH3; NH4 +