Glycosyl-Substituted Dicarboxylates as Detergents for the Extraction, Overstabilization, and Crystallization of Membrane Proteins

To tackle the problems associated with membrane protein (MP) instability in detergent solutions, we designed a series of glycosyl-substituted dicarboxylate detergents (DCODs) in which we optimized the polar head to clamp the membrane domain by including, on one side, two carboxyl groups that form salt bridges with basic residues abundant at the membrane-cytoplasm interface of MPs and, on the other side, a sugar to form hydrogen bonds. Upon extraction, the DCODs 8b, 8c, and 9b preserved the ATPase function of BmrA, an ATP-binding cassette pump, much more efficiently than reference or recently designed detergents. The DCODs 8a, 8b, 8f, 9a, and 9b induced thermal shifts of 20 to 29 degrees C for BmrA and of 13 to 21 degrees C for the native version of the G-protein-coupled adenosine receptor A(2A)R. Compounds 8f and 8g improved the diffraction resolution of BmrA crystals from 6 to 4 angstrom. DCODs are therefore considered to be promising and powerful tools for the structural biology of MPs.