Determining bilayer hydrocarbon thickness from neutron diffraction measurements using strip-function models

Journal Article · Thu May 01 04:00:00 EDT 1986 · Biophys. J.; (United States)

DOI:https://doi.org/10.1016/S0006-3495(86)83733-X· OSTI ID:5207526

King, G I; White, S H

Neutron diffraction methods provide information about the distribution of matter in biological and model membrane systems. The information is derived from plots (profiles) of scattering length density along an axis normal to the membrane plane. Without the use of specific deuteration, the generally low resolution of the profiles limits their interpretation in terms of specific chemical constituents (e.g., lipid headgroup, lipid hydrocarbon, protein, and water). A fundamental and useful structural assignment to make is the boundary between the headgroup and hydrocarbon regions of bilayers. We demonstrate here that strip-function model representations of neutron scattering length density profiles of bilayers are sufficient to determine accurately the position of the headgroup-hydrocarbon boundary. The resulting hydrocarbon thickness of the bilayer is useful for determining the area per lipid molecule and consequently the molecular packing arrangements of the membrane constituents. We analyze data obtained from dioleoylphosphatidylcholine (DOPC) bilayers at 66% RH using standard Fourier profile analyses and from DOPC deuterated specifically at the C-2 carbon of the acyl chains using difference Fourier analysis. We demonstrate that strip-function models accurately define the positions of the C-2 carbons and thus the hydrocarbon thickness (dhc) of the bilayer. We then show, using quasi-molecular models, that the strip-model analysis probably provides an accurate measure of dhc because of the exceptionally high scattering length density difference between the carbonyl and methylene groups.

• Research Organization: Univ. of California, Irvine
• OSTI ID: 5207526
• Journal Information: Biophys. J.; (United States), Journal Name: Biophys. J.; (United States) Vol. 5; ISSN BIOJA
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
CELL CONSTITUENTS
CELL MEMBRANES
COHERENT SCATTERING
DEUTERIUM COMPOUNDS
DIFFRACTION
DIMENSIONS
HYDROCARBONS
HYDROGEN COMPOUNDS
LAYERS
MEMBRANES
NEUTRON DIFFRACTION
ORGANIC COMPOUNDS
SCATTERING
STRUCTURAL CHEMICAL ANALYSIS
THICKNESS