Precise Control of Neutron Contrast in Surfactant Micelles Provides Platform for Membrane Structure Studies

Detergent Micelles
The scattering collected for detergent at its solution match point, where contrast still persists between core and shell, produces a non-flat scattering profile (red). Incorporating the non-ionic detergent DDM with deuterium-labelled chains allows matching of the core and shell contrast, producing the flat scattering profile shown in blue. [Reprinted with permission from Oliver, R. C., S. V. Pingali, and V. S. Urban. “Designing Mixed Detergent Micelles for Uniform Neutron Contrast.” J. Phys. Chem. Lett. 8, 5041–5046 (2017). [DOI: 10.1021/acs.jpclett.7b02149]. Copyright 2017 American Chemical Society.]
Scientists in this study have successfully demonstrated the ability to manipulate the neutron contrast of detergent micelles by incorporating a similar detergent with deuterium-labelled alkyl chains. The presence of excess detergent micelle scattering often has a detrimental influence on scattering data obtained for membrane protein–detergent complexes. Isolation of the scattering signal from the protein of interest can be accomplished by eliminating all scattering from the detergent. Using this approach enabled determination of the overall structure and oligomeric state of a small membrane protein enzyme.

Oliver, R. C., et al. “Designing Mixed Detergent Micelles for Uniform Neutron Contrast.” The Journal of Physical Chemistry Letters 8(20), 5041–5046 (2017). [DOI:10.1021/acs.jpclett.7b02149].

Instruments and Facilities Used: Small angle neutron scattering (SANS): Bio-SANS beamline (CG3) of the High-Flux Isotope Reactor at Oak Ridge National Laboratory (ORNL). Recorded scattering data using MantidPlot software. Neutron contrast studies: ModULes for the Analysis of Contrast (MULCh) Variation Data at University of Sydney (smb-research.smb.usyd.edu.au/NCVWeb/).