The Use of Amphipols for Solution NMR Studies of Membrane Proteins: Advantages and Constraints as Compared to Other Solubilizing Media Noelya Planchard • E ´ lodie Point • Tassadite Dahmane • Fabrice Giusti • Marie Renault • Christel Le Bon • Gre ´gory Durand • Alain Milon • E ´ ric Guittet • Manuela Zoonens • Jean-Luc Popot • Laurent J. Catoire Received: 28 November 2013 / Accepted: 7 March 2014 / Published online: 28 March 2014 Ó Springer Science+Business Media New York 2014 Abstract Solution-state nuclear magnetic resonance studies of membrane proteins are facilitated by the increased stability that trapping with amphipols confers to most of them as compared to detergent solutions. They have yielded information on the state of folding of the proteins, their areas of contact with the polymer, their dynamics, water accessibility, and the structure of protein- bound ligands. They benefit from the diversification of amphipol chemical structures and the availability of deu- terated amphipols. The advantages and constraints of working with amphipols are discussed and compared to those associated with other non-conventional environ- ments, such as bicelles and nanodiscs. Keywords Membrane proteins Á Solution NMR Á Amphipols Abbreviations APol Amphipol A8-35 Polyacrylate-based amphipol A8-35 BLT2 Low-affinity leukotriene receptor BR Bacteriorhodopsin C 8 E 4 Octyltetraoxyethylene CFE Cell-free expression CRINEPT Cross-correlated relaxation-enhanced polarization transfer DHPC Dihexanoylphosphatidylcholine DAPol A8-35 with perdeuterated octyl and isopropyl chains and a hydrogenated polyacrylate backbone DPC n-Dodecylphosphocholine DDM n-Dodecyl-b-D-maltopyranoside GPCR G protein-coupled receptor 12-HHT 12S-Hydroxyheptadeca-5Z,8E,10E-trienoic acid N. Planchard Á E ´ . Point Á T. Dahmane Á F. Giusti Á C. Le Bon Á M. Zoonens Á J.-L. Popot Á L. J. Catoire (&) Laboratoire de Biologie Physico-Chimique des Prote ´ines Membranaires, Institut de Biologie Physico-Chimique (FRC 550), UMR 7099, CNRS, Universite ´ Paris 7, 13 rue Pierre et Marie Curie, 75005 Paris, France e-mail: laurent.catoire@ibpc.fr Present Address: N. Planchard Centre de Versailles-Grignon, Institut Jean-Pierre Bourgin, UMR 1318 INRA-AgroParisTech, Ba ˆtiment 7, INRA, Route de St-Cyr, 78026 Versailles Cedex, France Present Address: T. Dahmane Department of Biochemistry and Molecular Biophysics, Columbia University, 650 West 168th Street, 202 BB, New York, NY 10032, USA M. Renault Á A. Milon Laboratoire de RMN et des interactions prote ´ines/membranes, CNRS, Institut de Pharmacologie et de Biologie Structurale, 205 route de Narbonne, BP64182, 31077 Toulouse, France G. Durand Equipe Chimie Bioorganique et Syste `mes Amphiphiles, Universite ´ d’Avignon et des Pays de Vaucluse, 33 rue Louis Pasteur, 84000 Avignon, France G. Durand Institut des Biomole ´cules Max Mousseron (UMR 5247), 15 avenue Charles Flahault, 34093 Montpellier Cedex 05, France E ´ . Guittet Centre de Recherche de Gif, Laboratoire de Chimie et Biologie Structurales, UPR 2301 CNRS, ICSN, 91198 Gif-sur-Yvette, France 123 J Membrane Biol (2014) 247:827–842 DOI 10.1007/s00232-014-9654-z