Molecular dynamics studies of polyethylene oxide and polyethylene glycol: hydrodynamic radius and shape anisotropy.

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TitleMolecular dynamics studies of polyethylene oxide and polyethylene glycol: hydrodynamic radius and shape anisotropy.
Publication TypeJournal Article
Year of Publication2008
AuthorsLee, H, Venable, RM, Mackerell, AD, Pastor, RW
JournalBiophys J
Volume95
Issue4
Pagination1590-9
Date Published2008 Aug
ISSN1542-0086
KeywordsAnisotropy, Computer Simulation, Models, Chemical, Models, Molecular, Molecular Conformation, Polyethylene Glycols, Pressure
Abstract

A revision (C35r) to the CHARMM ether force field is shown to reproduce experimentally observed conformational populations of dimethoxyethane. Molecular dynamics simulations of 9, 18, 27, and 36-mers of polyethylene oxide (PEO) and 27-mers of polyethylene glycol (PEG) in water based on C35r yield a persistence length lambda = 3.7 A, in quantitative agreement with experimentally obtained values of 3.7 A for PEO and 3.8 A for PEG; agreement with experimental values for hydrodynamic radii of comparably sized PEG is also excellent. The exponent upsilon relating the radius of gyration and molecular weight (R(g) proportional, variantM(w)(upsilon)) of PEO from the simulations equals 0.515 +/- 0.023, consistent with experimental observations that low molecular weight PEG behaves as an ideal chain. The shape anisotropy of hydrated PEO is 2.59:1.44:1.00. The dimension of the middle length for each of the polymers nearly equals the hydrodynamic radius R(h)obtained from diffusion measurements in solution. This explains the correspondence of R(h) and R(p), the pore radius of membrane channels: a polymer such as PEG diffuses with its long axis parallel to the membrane channel, and passes through the channel without substantial distortion.

DOI10.1529/biophysj.108.133025
Alternate JournalBiophys. J.
PubMed ID18456821
PubMed Central IDPMC2483782
Grant ListR01 GM070855 / GM / NIGMS NIH HHS / United States
GM51501 / GM / NIGMS NIH HHS / United States
/ / Intramural NIH HHS / United States
GM070855 / GM / NIGMS NIH HHS / United States
R01 GM051501 / GM / NIGMS NIH HHS / United States
R29 GM051501 / GM / NIGMS NIH HHS / United States