scholarly journals Contrast-Matching Detergent in Small-Angle Neutron Scattering Experiments for Membrane Protein Structural Analysis and Ab Initio Modeling

10.3791/57901 ◽  
2018 ◽  
Author(s):  
Ryan C. Oliver ◽  
Swe-Htet Naing ◽  
Kevin L. Weiss ◽  
Sai Venkatesh Pingali ◽  
Raquel L. Lieberman ◽  
...  
Keyword(s):  
Structural Analysis ◽  
Membrane Protein ◽  
Neutron Scattering ◽  
Ab Initio ◽  
Small Angle ◽  
Small Angle Neutron Scattering ◽  
Protein Structural Analysis ◽  
Contrast Matching

scholarly journals Membrane Protein Structures in Lipid Bilayers; Small-Angle Neutron Scattering With Contrast-Matched Bicontinuous Cubic Phases

2021 ◽  
Vol 8 ◽  
Author(s):  
Charlotte E. Conn ◽  
Liliana de Campo ◽  
Andrew E. Whitten ◽  
Christopher J. Garvey ◽  
Anwen M. Krause-Heuer ◽  
...  
Keyword(s):  
Membrane Protein ◽  
Neutron Scattering ◽  
Phase Behavior ◽  
Lipid Bilayers ◽  
Small Angle ◽  
Small Angle Neutron Scattering ◽  
Protein Structures ◽  
Bicontinuous Cubic ◽  
Contrast Matching ◽  
Detergent Micelles

This perspective describes advances in determining membrane protein structures in lipid bilayers using small-angle neutron scattering (SANS). Differentially labeled detergents with a homogeneous scattering length density facilitate contrast matching of detergent micelles; this has previously been used successfully to obtain the structures of membrane proteins. However, detergent micelles do not mimic the lipid bilayer environment of the cell membrane in vivo. Deuterated vesicles can be used to obtain the radius of gyration of membrane proteins, but protein-protein interference effects within the vesicles severely limits this method such that the protein structure cannot be modeled. We show herein that different membrane protein conformations can be distinguished within the lipid bilayer of the bicontinuous cubic phase using contrast-matching. Time-resolved studies performed using SANS illustrate the complex phase behavior in lyotropic liquid crystalline systems and emphasize the importance of this development. We believe that studying membrane protein structures and phase behavior in contrast-matched lipid bilayers will advance both biological and pharmaceutical applications of membrane-associated proteins, biosensors and food science.

scholarly journals Determining the amphipol distribution within membrane-protein fibre samples using small-angle neutron scattering

2018 ◽  
Vol 74 (12) ◽  
pp. 1192-1199 ◽  
Author(s):  
Wanatchaporn Arunmanee ◽  
Richard K. Heenan ◽  
Jeremy H. Lakey
Keyword(s):  
Membrane Protein ◽  
Neutron Scattering ◽  
Small Angle ◽  
Small Angle Neutron Scattering ◽  
Oblate Spheroid ◽  
Critical Micellar Concentration ◽  
Polymeric Surfactants ◽  
Contrast Matching ◽  
Outer Membrane Protein F

Detergent micelles can solubilize membrane proteins, but there is always a need for a pool of free detergent at the critical micellar concentration to maintain the micelle–monomer equilibrium. Amphipol polymeric surfactants (APols) have been developed to replace conventional detergents in membrane-protein studies, but the role of free amphipol is unclear. It has previously been shown that the removal of free APol causes monodisperse outer membrane protein F (OmpF) to form long filaments. However, any remaining APol could not be resolved using electron microscopy. Here, small-angle neutron scattering with isotope contrast matching was used to separately determine the distributions of membrane protein and amphipol in a mixed sample. The data showed that after existing free amphipol had been removed from monodisperse complexes, a new equilibrium was established between protein–amphipol filaments and a pool of newly liberated free amphipol. The filaments consisted of OmpF proteins surrounded by a belt of Apol, whilst free oblate spheroid micelles of Apol were also present. No indications of long-range order were observed, suggesting a lack of defined structure in the filaments.

Porosity of the Marcellus Shale: A contrast matching small-angle neutron scattering study

2018 ◽  
Vol 188 ◽  
pp. 156-164 ◽  
Author(s):  
Jitendra Bahadur ◽  
Leslie F. Ruppert ◽  
Vitaliy Pipich ◽  
Richard Sakurovs ◽  
Yuri B. Melnichenko
Keyword(s):  
Neutron Scattering ◽  
Small Angle ◽  
Small Angle Neutron Scattering ◽  
Marcellus Shale ◽  
Scattering Study ◽  
Neutron Scattering Study ◽  
Contrast Matching

scholarly journals Small Angle Neutron Scattering from Nanophase Titanium As A Function of Oxidation

1988 ◽  
Vol 132 ◽  
Author(s):  
J. A. Eastman ◽  
J. E. Epperson ◽  
H. Hahn ◽  
T. E. Klippert ◽  
A. Narayanasamy ◽  
...  
Keyword(s):  
Neutron Scattering ◽  
Small Angle ◽  
Small Angle Neutron Scattering ◽  
Scattering Length ◽  
Contrast Variation ◽  
Gas Condensation ◽  
Pressure Oxygen ◽  
Scattering Centers ◽  
Scattering Lengths ◽  
Contrast Matching

ABSTRACTNanophase titanium, prepared by the gas-condensation method both as aggregated powder and in lightly compacted discs, has been studied by conventional small angle neutron scattering, and by use of contrast variation methods. The contrast has been changed (a), isotopically, by means of deuterated/protonated solvents distilled into the specimen and (b) by progressive incremental oxidation of the Ti particles using fixed doses of low-pressure oxygen. It was shown that some evolution of the small angle pattern for lightly compacted nanophase Ti occurred over a period of several months at 300 K. Contrast matching by external solvent works well and has allowed the scattering lengths of oxidized and unoxidized specimens to be followed. The results imply that the scattering from metal and oxide can be separated under suitable conditions. The partial oxidation experiments indicate that there is both a fast and slow oxidation at 300 K. Also, during slow oxidation, high scattering length density scattering centers were formed whose number increased, but whose size remained the same at about 2 nm; these centers are tentatively assumed to be TiO2.

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