Revisiting the bilayer structures of fluid phase phosphatidylglycerol lipids: Accounting for exchangeable hydrogens

Document Type

Article

Publication Date

1-1-2014

Publication Title

Biochimica et Biophysica Acta - Biomembranes

Volume

1838

Issue

11

First Page

2966

Keywords

Hydrogen exchange, Lipid bilayer structure, MD simulations, PG lipid, SANS, SAXS

Last Page

2969

Abstract

We recently published two papers detailing the structures of fluid phase phosphatidylglycerol (PG) lipid bilayers (Kučerka et al., 2012 J. Phys. Chem. B 116: 232-239; Pan et al., 2012 Biochim. Biophys. Acta Biomembr. 1818: 2135-2148), which were determined using the scattering density profile model. This hybrid experimental/computational technique utilizes molecular dynamics simulations to parse a lipid bilayer into components whose volume probabilities follow simple analytical functional forms. Given the appropriate scattering densities, these volume probabilities are then translated into neutron scattering length density (NSLD) and electron density (ED) profiles, which are used to jointly refine experimentally obtained small angle neutron and X-ray scattering data. However, accurate NSLD and ED profiles can only be obtained if the bilayer's chemical composition is known. Specifically, in the case of neutron scattering, the lipid's exchangeable hydrogens with aqueous D 2O must be accounted for, as they can have a measureable effect on the resultant lipid bilayer structures. This was not done in our above-mentioned papers. Here we report on the molecular structures of PG lipid bilayers by appropriately taking into account the exchangeable hydrogens. Analysis indicates that the temperature-averaged PG lipid areas decrease by 1.5 to 3.8 Å2, depending on the lipid's acyl chain length and unsaturation, compared to PG areas when hydrogen exchange was not taken into account. © 2014 Elsevier B.V.

DOI

10.1016/j.bbamem.2014.08.009

ISSN

00052736

E-ISSN

18792642

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