Open AccessSurface Shear Viscosity and Interleaflet Friction from Nonequilibrium Simulations of Lipid Bilayers
Author(s) -
Andrew Zgorski,
Richard W. Pastor,
Edward Lyman
Publication year - 2019
Publication title -
journal of chemical theory and computation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.001
H-Index - 185
eISSN - 1549-9626
pISSN - 1549-9618
DOI - 10.1021/acs.jctc.9b00683
Subject(s) - rheology , thermodynamics , materials science , viscosity , newtonian fluid , non equilibrium thermodynamics , shear thinning , dissipation , shear (geology) , diffusion , ternary operation , plateau (mathematics) , phase (matter) , yield (engineering) , chemistry , physics , composite material , mathematics , mathematical analysis , organic chemistry , computer science , programming language
Nonequilibrium simulation protocols based on shear deformations are applied to determine the surface viscosity and interleaflet friction of lipid bilayers. At high shear rates, a non-Newtonian shear thinning regime is observed, but lower shear rates yield a Newtonian plateau and results that are consistent with equilibrium measurements based on fluctuation-dissipation theorems. Application to all-atom bilayers modeled with the CHARMM36 parameter set yields values for the surface viscosity that are consistent with microscopic measurements based on membrane protein diffusion but are approximately 10 times lower than more macroscopic experimental measurements. The interleaflet friction is about 10 times lower than experimental measurements. Trends across different lipids, temperatures, and ternary liquid-disordered phase mixtures produce results that are consistent with experimental diffusion constants. Application of the protocol to the liquid-ordered phase fails to yield a Newtonian plateau, suggesting more complex rheology.