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

Lookup NU author(s): Professor Jeremy LakeyORCiD



This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).


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.

Publication metadata

Author(s): Arunmanee W, Heenanc RK, Lakey JH

Publication type: Article

Publication status: Published

Journal: Acta Crystallographica Section D

Year: 2018

Volume: 74

Issue: 12

Pages: 1192-1199

Print publication date: 01/12/2018

Online publication date: 30/11/2018

Acceptance date: 22/03/2018

Date deposited: 20/12/2018

ISSN (electronic): 2059-7983

Publisher: International Union of Crystallography


DOI: 10.1107/S205979831800476X


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Funder referenceFunder name
093581/Z/10/ZWellcome Trust