Dependence of micelle size and shape on detergent alkyl chain length and head group

Dependence of micelle size and shape on detergent alkyl chain length and head group

Oliver, R.C.
Lipfert, J.
Fox, D.A.
Lo, R.H.
Doniach, S.
Columbus, L.

Applied Sciences

Bionanoscience

2013-05-08

Micelle-forming detergents provide an amphipathic environment that can mimic lipid bilayers and are important tools for solubilizing membrane proteins for functional and structural investigations in vitro. However, the formation of a soluble protein-detergent complex (PDC) currently relies on empirical screening of detergents, and a stable and functional PDC is often not obtained. To provide a foundation for systematic comparisons between the properties of the detergent micelle and the resulting PDC, a comprehensive set of detergents commonly used for membrane protein studies are systematically investigated. Using small-angle X-ray scattering (SAXS), micelle shapes and sizes are determined for phosphocholines with 10, 12, and 14 alkyl carbons, glucosides with 8, 9, and 10 alkyl carbons, maltosides with 8, 10, and 12 alkyl carbons, and lysophosphatidyl glycerols with 14 and 16 alkyl carbons. The SAXS profiles are well described by two-component ellipsoid models, with an electron rich outer shell corresponding to the detergent head groups and a less electron dense hydrophobic core composed of the alkyl chains. The minor axis of the elliptical micelle core from these models is constrained by the length of the alkyl chain, and increases by 1.2–1.5 A° per carbon addition to the alkyl chain. The major elliptical axis also increases with chain length; however, the ellipticity remains approximately constant for each detergent series. In addition, the aggregation number of these detergents increases by ,16 monomers per micelle for each alkyl carbon added. The data provide a comprehensive view of the determinants of micelle shape and size and provide a baseline for correlating micelle properties with protein-detergent interactions.

http://resolver.tudelft.nl/uuid:c226010a-5572-4b96-b924-42ebf0b66963

https://doi.org/10.1371/journal.pone.0062488

Public Library of Science

1932-6203

http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0062488

Plos One, 8 (5), 2013

Institutional Repository

journal article

(c) 2013 Oliver et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.