Fig. 3. Thermosolubility and functional profiles of detergent-solubilised MelBSt. The solubility test at elevated temperatures was carried out as described in the ESI.† (a) Solubilised materials after ultracentrifugation of detergent-treated membranes were analysed by SDS-15%PAGE and Western blot. The total amount of MelBSt protein used in each assay is shown by the untreated membrane sample (Memb). (b) Histogram of band density. The solubilisation efficiency of MelBSt is expressed as a percentage of band density relative to the untreated membrane sample. The density was measured by ImageQuant software. Error bars, SEM, n = 2–4. (c) Galactoside binding. Right-side-out (RSO) membrane vesicles containing MelBSt or MelBEc were solubilised with DDM or NDT-C11 as described in the ESI.† After ultracentrifugation, the supernatant was used to test melibiose reversal of Trp to dansyl-2-galacotside (D2G) FRET. Note the difference in FRET response of the D2G bound MelB to melibiose or water addition at the 2 min point.
