Neutron Scattering at the Intersection of Heart Health Science and Biophysics

Marquardt, Drew; Alsop, Richard J.; Rheinstädter, Maikel C.; Harroun, Thad A.

doi:10.3390/jcdd2020125

“…These techniques are ideally suited to study molecular structure and dynamical properties of membranes13213940414243444546. The approach has advanced significantly during the past decades and is now used to study complex, multi-component membranes and their interaction with drugs, small molecules1320263747484950515253, bacteria5455, and in particular lipid rafts, i.e. functional lipid domains16175657585960.…”

Section: Discussionmentioning

confidence: 99%

The Molecular Structure of Human Red Blood Cell Membranes from Highly Oriented, Solid Supported Multi-Lamellar Membranes

Himbert

¹

,

Alsop

²

,

Rose

³

et al. 2017

Sci Rep

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We prepared highly oriented, multi-lamellar stacks of human red blood cell (RBC) membranes applied on silicon wafers. RBC ghosts were prepared by hemolysis and applied onto functionalized silicon chips and annealed into multi-lamellar RBC membranes. High resolution X-ray diffraction was used to determine the molecular structure of the stacked membranes. We present direct experimental evidence that these RBC membranes consist of nanometer sized domains of integral coiled-coil peptides, as well as liquid ordered (lo) and liquid disordered (ld) lipids. Lamellar spacings, membrane and hydration water layer thicknesses, areas per lipid tail and domain sizes were determined. The common drug aspirin was added to the RBC membranes and found to interact with RBC membranes and preferably partition in the head group region of the lo domain leading to a fluidification of the membranes, i.e., a thinning of the bilayers and an increase in lipid tail spacing. Our results further support current models of RBC membranes as patchy structures and provide unprecedented structural details of the molecular organization in the different domains.

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“…These techniques are ideally suited to study molecular structure and dynamical properties of membranes 13,21,[39][40][41][42][43][44][45][46] . The approach has advanced significantly during the past decades and is now used to study complex, multi-component membranes and their interaction with drugs, small molecules 13,20,26,37,[47][48][49][50][51][52][53] , bacteria 54,55 , and in particular lipid rafts, i.e. functional lipid domains 16,17,[56][57][58][59][60] .…”

Section: Discussionmentioning

confidence: 99%

The Molecular Structure of Human Red Blood Cell Membranes From Highly Oriented, Solid Supported Multi-Lamellar Membranes

Himbert

¹

,

Alsop

²

,

Rheinstädter

³

2018

Biophysical Journal

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We prepared highly oriented, multi-lamellar stacks of human red blood cell (RBC) membranes applied on silicon wafers. RBC ghosts were prepared by hemolysis and applied onto functionalized silicon chips and annealed into multi-lamellar RBC membranes. High resolution X-ray diffraction was used to determine the molecular structure of the stacked membranes. We present direct experimental evidence that these RBC membranes consist of nanometer sized domains of integral coiled-coil peptides, as well as liquid ordered (l o ) and liquid disordered (l d ) lipids. Lamellar spacings, membrane and hydration water layer thicknesses, areas per lipid tail and domain sizes were determined. The common drug aspirin was added to the RBC membranes and found to interact with RBC membranes and preferably partition in the head group region of the l o domain leading to a fluidification of the membranes, i.e., a thinning of the bilayers and an increase in lipid tail spacing. Our results further support current models of RBC membranes as patchy structures and provide unprecedented structural details of the molecular organization in the different domains.The presence of pale cells with no internal content in a blood smear is typically indicative of a disease. These cells are produced by hemolysis and have been named red blood cell (RBC) ghosts based on their appearance under the microscope. RBC ghosts can be prepared artificially [1][2][3] . The first published protocol in 1963 by Dodge, Mitchell and Hanahan describes the extraction of the cell membrane from RBCs through hemolysis and was an essential step in the development of membrane proteomics and lipidomics 4,5 . While there is detailed knowledge of the composition of RBC membranes, information about the molecular organization of these components in the actual membranes is scarce 6 . This is, in particular, a consequence of the lack of suitable experimental techniques. The disordered, patchy and highly dynamic state of biological materials impedes, for instance, the use of high-resolution diffraction techniques as in protein crystallography. To overcome this constraint, we prepared highly oriented stacks of RBC membranes on silicon wafers and studied their molecular properties in-vitro using high resolution X-ray diffraction. The results present evidence for nanometer-sized domains of coiled-coils peptides, as well as liquid ordered (l o ) and liquid disordered (l d ) lipid patches, and give a detailed picture of the molecular organization in these domains.When present in the body, aspirin (acetylsalicylic acid, ASA) and its metabolites interact with the cyclo-oxygenase (COX) pathway. The inhibition of both COX isoforms, COX-1 and COX-2, by higher dose aspirin is believed to lead to analgesic and anti-inflammatory effects, while lower doses, sufficient to inhibit COX-1 activity, lead to anti-platelet activity 7,8 . There is recent evidence that membrane composition and fluidity play an important role in platelet cell function [9][10][11] , possibly related to the formation of rafts 12 .

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“…Neutron diffraction from aligned membrane systems has yielded insights into systems such as fat-soluble nutrients, pharmaceuticals and biological processes (Marquardt et al, 2015). Aligned membrane systems have a distinct advantage over liposomes, as they allow for the model-free analysis of data.…”

Section: Introductionmentioning

confidence: 99%

Neutron diffraction from aligned stacks of lipid bilayers using the WAND instrument

Marquardt

¹

,

Frontzek

²

,

Zhao

³

et al. 2018

Self Cite

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1 This article will form part of a virtual special issue on advanced neutron scattering instrumentation, marking the 50th anniversary of the journal.Neutron diffraction from aligned stacks of lipid bilayers is examined using the Wide-Angle Neutron Diffractometer (WAND), located at the High Flux Isotope Reactor, Oak Ridge, Tennessee, USA. Data were collected at different levels of hydration and neutron contrast by varying the relative humidity (RH) and H 2 O/D 2 O ratio from multi-bilayers of dioleoylphosphatidylcholine and sunflower phosphatidylcholine extract aligned on single-crystal silicon substrates. This work highlights the capabilites of a newly fabricated sample hydration cell, which allows the lipid bilayers to be hydrated with varying H/D ratios from the RH generated by saturated salt solutions, and also demonstrates WAND's capability as an instrument suitable for the study of aligned lipid multibilayers. research papers J. Appl. Cryst. (2018). 51, 235-241 Drew Marquardt et al. Aligned stacks of lipid bilayers 241

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Neutron Scattering at the Intersection of Heart Health Science and Biophysics

Cited by 5 publications

References 61 publications

The Molecular Structure of Human Red Blood Cell Membranes from Highly Oriented, Solid Supported Multi-Lamellar Membranes

The Molecular Structure of Human Red Blood Cell Membranes from Highly Oriented, Solid Supported Multi-Lamellar Membranes

The Molecular Structure of Human Red Blood Cell Membranes From Highly Oriented, Solid Supported Multi-Lamellar Membranes

Neutron diffraction from aligned stacks of lipid bilayers using the WAND instrument

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