As we ring in 2016, we wanted to pause to look back at a year that was full of exciting changes and new, innovative products. The year started out with our acquisition of Microlytic, allowing Anatrace to become a premier provider of crystallization tools and reagents for the structural biology laboratory. We later announced the launch of our new line of protein purification products, allowing us to further support your research. Lastly, continuing our tradition of innovation and higher standards, we also added a number of new detergents to our catalog, including six new Alkyl PEG detergents, GDN, and a DDM-CHS Mixture.
2015 was also a very exciting year for membrane protein research. An astonishing 62 unique membrane protein structures were determined in 2015 (Data from 1, as of 01/08/2016 (1)). Here, we’ll take a closer look at the structures that were published in 2015, and provide some analysis about what detergents worked best for your research:
Of the 62 structures, 47 were determined by X-ray crystallography, 10 by Cryo-EM, 3 by NMR, and 2 by Serial Femtosecond Crystallography (LCP-SFX) (Figure 1). Looking closer at the structures determined by X-ray crystallography, 29 were crystallized using standard vapor diffusion methods, 15 by LCP, and 2 were crystallized in bicelles.
We then sought to answer the question of which detergents were used most frequently for the extraction of the membrane proteins. As expected, the majority of proteins (43%) were solubilized in DDM. The second most popular detergent used for solubilization was a DDM / CHS mixture, used in 19% of the structures, including all 6 of the GPCR structures. Rounding out the top three solubilization detergents was DM, being used in 7% of the structures. A summary of all of the detergents used in solubilization is illustrated in Figure 2.
Lastly, we examined which detergents were used most often for the final purification step (usually Size Exclusion Chromatography) and the structure determination experiments. Similar to above, the most popular detergents were DDM (24% of the structures), followed by DDM / CHS (11% of the structures). Rounding out the list were DM, NG, C8E4, and the increasingly popular LMNG, each being used in 6% of the structures. Interestingly, C8E4 was only used in the structure determination of β-barrel proteins. A summary of all of the detergents used in the final purification and structure determination is illustrated in Figure 3.
If you valued this overview, we’ll be launching a new detergent database this summer which will contain detailed information about detergent usage and structure determination methods for all of the membrane proteins in the known database.
1) Membrane Proteins of Known 3D Structure. Steven White Laboratory. Accessed 01/08/2016: http://blanco.biomol.uci.edu/mpstruc/