Biophysical characterization of integral membrane proteins, particularly at the atomic level, is hampered by the necessity of removing these sensitive and flexible proteins from their natural environment – the cell membrane. This extraction is most commonly achieved through the addition of detergents or detergent mixtures, occasionally supplemented with purified lipids.
A frequent consequence, however, is the production of unstable, aggregated, or denatured protein that is unsuitable for functional or structural characterization. More and more, research into stabilizing conditions for membrane proteins is highlighting the importance of detergent selection and the tremendous impact that the choice of detergent can have on the stability and crystallizability of an integral membrane protein.
In 2011, Anatrace was first to market with a new class of detergents which were hailed as a breakthrough for membrane protein researchers. This NG Class of detergents is based on the maltose neopentyl amphiphile first described by Chae et al. in 2010(1). Since then, this class of detergents has grown along with their published success.
In just the past few months, NG Class detergents have been instrumental for stabilizing a diverse group of integral membrane proteins for crystallographic studies, including the GPCR GPC40(2), NMDA iGluR receptor(3), and the β3 homopentamer of human GABAaR(4). Furthermore, Lauryl Maltose Neopentyl Glycol (MNG) has been identified as a key stabilizing factor for the 2F2hc-LAT2 protein, enabling the generation of a solid 3-D map through TEM and single particle analysis(5). In this 4F2hc-LAT2 example by Meury, they showed that purification in DDM-solubilized membranes produced mixtures of products. Adding additional detergents, namely a mixture of DDM, LMNG, and CHS not only provided pure 4F2hc-LAT2 complexes, but they were stable for up to six days. This clearly paves the way for new functional and structural studies.
Physically, this family of detergents possesses important characteristics that are particularly beneficial to protein crystallization. These detergents are capable of dense packing which increases the thermal stability of the detergent/protein complex. This also results in exceptionally low critical micelle concentrations and extreme water solubility. These low CMC values reduce the often detrimental effects of excess solubilizing agent on crystallization and permit successful expression in cell free protein expression systems without interfering with protein synthesis.
Introduce the NG family to your research with one of our eight NG Class detergents:
Uncertain which is best for your integral membrane target? Consider using our Analytic Selector Kit to rapidly identify detergents that improve the stability of your protein.
Chae, P. S. et al. Maltose-Neopentyl Glycol (MNG) Amphiphiles for Solubilization, Stabilization, and Crystallization of Membrane Proteins. (2010) Nature Methods 7(12), 1003-1008.
Srivastava, A. et al. High-Resolution Structure of the Human GPR40 Receptor Bound to Allosteric Agonist TAK-875. (2014) Nature 513, 124-127.
Karakas, E. and Furukawa, H. Crystal Structure of a Heterotetrameric NMDA Receptor Ion Channel. (2014) Science 344, 992-997.
Miller, P. S. and Aricescu, A. R. Crystal Structure of a Human GABAA Receptor. (2014) Nature 512, 270-275.
Meury, M. et al. Detergent-Induced Stabilization and Improved 3D Map of the Human Heteromeric Amino Acid Transporter 4F2hc-LAT2. (2014) PLoS One 9(10), e109882.