NaCl interactions with phosphatidylcholine bilayers do not alter membrane structure but induce long-range ordering of ions and water |
| |
Authors: | Valley Christopher C Perlmutter Jason D Braun Anthony R Sachs Jonathan N |
| |
Institution: | (1) Department of Biomedical Engineering, University of Minnesota, Minneapolis, MN 55455, USA; |
| |
Abstract: | It is generally accepted that ions interact directly with lipids in biological membranes. Decades of biophysical studies on
pure lipid bilayer systems have shown that only certain types of ions, most significantly large anions and multivalent cations,
can fundamentally alter the structure and dynamics of lipid bilayers. It has long been accepted that at physiological concentrations
NaCl ions do not alter the physical behavior or structure of bilayers composed solely of zwitterionic phosphatidylcholine
(PC) lipids. Recent X-ray scattering experiments have reaffirmed this dogma, showing that below 1 M concentration, NaCl does
not significantly alter bilayer structure. However, despite this history, there is an ongoing controversy within the molecular
dynamics (MD) simulation community regarding NaCl/PC interactions. In particular, the CHARMM and GROMOS force fields show
dramatically different behavior, including the effect on bilayer structure, surface potential, and the ability to form stable,
coordinated ion–lipid complexes. Here, using long-timescale, constant-pressure simulations under the newest version of the
CHARMM force field, we find that Na+ and Cl− associate with PC head groups in a POPC bilayer with approximately equal, though weak, affinity, and that the salt has a
negligible effect on bilayer structure, consistent with earlier CHARMM results and more recent X-ray data. The results suggest
that interpretation of simulations where lipids interact with charged groups of any sort, including charged proteins, must
be carefully scrutinized. |
| |
Keywords: | |
本文献已被 PubMed SpringerLink 等数据库收录! |
|