What do you do when the standard doesn't work?
You set it higher.

For years, the de facto standard detergent for the solubilization and purification of membrane proteins has been Dodecyl-β-D-Maltoside (DDM, D310). This is evidenced by the use of DDM in the solubilization of over 55% of the membrane protein structures determined in 2015. Further supporting this claim is the rise in popularity and usage of the detergent Lauryl Maltose Neopentyl Glycol (LMNG, NG310) in recent years. The chemical structure of LMNG is essentially two DDM molecules linked together by a central quaternary carbon. The success of these two detergents suggest that the combination of a disaccharide linked to a 12-carbon alkyl tail is important to the solubilization and stabilization of membrane proteins.
 
In 2012, the labs of Ray Stevens and Qinghai Zhang at The Scripps Research Institute(1), took advantage of this fact when designing a new class of Dodecyl Trehaloside detergents (DDTre)(2). The basic chemical structure of these new detergents is similar to that of DDM, with a 12-carbon alkyl chain attached to different hydroxyl groups of the disaccharide trehalose (Figure 1). As an additive commonly used in life sciences research, trehalose has shown protective effects on both proteins and lipid bilayers(3). Each of the structural isomers of these trehaloside detergents show differences in molecular geometry, which has an effect on the properties of the detergents when compared to DDM. The main properties of the three new trehaloside detergents are summarized in Table 1.

Figure 1: Images of new Trehaloside detergents.

Table 1: Properties of trehaloside detergents compared to the maltoside detergent, DDM.

a.       Calculated by RP-HPLC. k’ = HPCL retention factor.
b.      Calculated via fluorescence assay with 8-anilino-1-naphtalenesulfonic acid (ANS).
c.       Determined via Dynamic Light Scattering.
 

These new trehaloside detergents were tested on the GPCR N/OFQ opioid receptor ORL1.  Prior to this study, the structure of this protein has been determined with the use of DDM:CHS(4).  For solubilization of ORL1 from insect cell membranes, all three of the new detergents performed similarly as DDM; however, in thermal stability assays, the detergents 4-DDTre and 6-DDTre showed superiority over DDM, yielding a 7.5oC and 1.8oC increase in the Tm of ORL1, respectively.  

When selecting a detergent, it is of critical importance to understand the effects that both the hydrophobic chain length and polar head group can have on the stability and crystallizability of your membrane protein. At Anatrace we are committed to continually developing and innovating to provide you the tools you need to select the right detergent allowing you to set your standards higher.

References:
1)      Ray Stevens is currently a professor at the University of Southern California.
2)      Tao, H., et al. (2012) Langmuir, 28(30), 11173-11181.
3)      Ohtake, S. and Wang, Y. J. (2011) J. Pharm. Sci., 100(6), 2020−2053.
4)      Thompson, A.A. et al. (2012) Nature, 485(7398), 395-399.