Effect of Water Hydrogen Bonding on the Solvent-Mediated “Oscillatory” Repulsion of C60 Fullerenes in Water

2015 ◽  
Vol 6 (9) ◽  
pp. 1761-1766 ◽  
Author(s):  
Yuri S. Djikaev ◽  
Eli Ruckenstein
Keyword(s):  
Hydrogen Bonding ◽  
Effect Of Water ◽  
Water Hydrogen ◽  
C60 Fullerenes

scholarly journals Functional stability of water wire–carbonyl interactions in an ion channel

2020 ◽  
Vol 117 (22) ◽  
pp. 11908-11915 ◽  
Author(s):  
Joana Paulino ◽  
Myunggi Yi ◽  
Ivan Hung ◽  
Zhehong Gan ◽  
Xiaoling Wang ◽  
...  
Keyword(s):  
Hydrogen Bonding ◽  
Nmr Spectroscopy ◽  
Lipid Bilayers ◽  
Density Functional ◽  
Liquid Crystalline ◽  
Density Functional Theory Calculations ◽  
Bulk Water ◽  
Simple Explanation ◽  
Dynamics Simulations ◽  
Water Hydrogen

Water wires are critical for the functioning of many membrane proteins, as in channels that conduct water, protons, and other ions. Here, in liquid crystalline lipid bilayers under symmetric environmental conditions, the selective hydrogen bonding interactions between eight waters comprising a water wire and a subset of 26 carbonyl oxygens lining the antiparallel dimeric gramicidin A channel are characterized by17O NMR spectroscopy at 35.2 T (or 1,500 MHz for1H) and computational studies. While backbone15N spectra clearly indicate structural symmetry between the two subunits, single site17O labels of the pore-lining carbonyls report two resonances, implying a break in dimer symmetry caused by the selective interactions with the water wire. The17O shifts document selective water hydrogen bonding with carbonyl oxygens that are stable on the millisecond timescale. Such interactions are supported by density functional theory calculations on snapshots taken from molecular dynamics simulations. Water hydrogen bonding in the pore is restricted to just three simultaneous interactions, unlike bulk water environs. The stability of the water wire orientation and its electric dipole leads to opposite charge-dipole interactions for K+ions bound at the two ends of the pore, thereby providing a simple explanation for an ∼20-fold difference in K+affinity between two binding sites that are ∼24 Å apart. The17O NMR spectroscopy reported here represents a breakthrough in high field NMR technology that will have applications throughout molecular biophysics, because of the acute sensitivity of the17O nucleus to its chemical environment.

Carbonyl–water hydrogen bonding: The H2CO–H2O prototype

1994 ◽  
Vol 100 (6) ◽  
pp. 4347-4354 ◽  
Author(s):  
Theresa A. Ramelot ◽  
Ching‐Han Hu ◽  
Joseph E. Fowler ◽  
Bradley J. DeLeeuw ◽  
Henry F. Schaefer
Keyword(s):  
Hydrogen Bonding ◽  
Water Hydrogen
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