Maltose-Based Fluorinated Surfactants for Membrane-Protein Extraction and Stabilization

Abstract

Two new surfactants, F 5 OM and F 5 DM, were designed as partially fluorinated analogs of ndodecyl-β-D-maltoside (DDM). The micellization properties and the morphologies of the aggregates formed by the two surfactants in water and phosphate buffer were evaluated by NMR spectroscopy, surface tension measurement (SFT), isothermal titration calorimetry (ITC), dynamic light scattering (DLS), small-angle X-ray scattering (SAXS), and analytical ultracentrifugation (AUC). As expected, the critical micellar concentration (CMC) was found to decrease with chain length of the fluorinated tail from 2.1-2.5 mM for F 5 OM to 0.3-0.5 mM for F 5 DM, and micellization was mainly entropy-driven at 25°C. Close to their respective CMC, the micelle sizes were similar for both surfactants i.e. 7 and 13 nm for F 5 OM and F 5 DM, respectively and both increased with concentration forming 4 nm diameter rods with maximum dimensions of 50 and 70 nm, respectively, at a surfactant concentration of ~30 mM. The surfactants were found to readily solubilize lipid vesicles and extract membrane proteins (MPs) directly from Escherichia coli membranes. They were found more efficient than the commercial fluorinated detergent F 6 H 2 OM over a broad range of concentrations (1-10 mM) and even better than DDM at low concentrations (1-5 mM). When transferred into the two new surfactants, the thermal stability of the proteins bacteriorhodopsin (bR) and FhuA were higher than in the presence of their solubilization detergents and similar to that in DDM; furthermore, bR was stable over several months. The membrane enzymes SpNOX and BmrA were not as active as in DDM micelles but similarly active as in F 6 OM. Together, these findings indicate both extracting and stabilizing properties of the new maltose-based fluorinated surfactants, making them promising tools in MPs applications.

A Surfactant Concentration Model for the Systematic Determination of the Critical Micellar Concentration and the Transition Width

“…The cmc values obtained with the concentration model from ST and from NMR spectroscopy data of fluorinated surfactants agree within the experimental error with the results from ITC, dynamic light scattering, small-angle X-ray scattering, and analytical ultracentrifugation [41][42][43].…”

“…As mentioned before, in a series of publications, Durand and coworkers, used Equation (18) to analyse 19 F NMR-shift data and obtained good coincidence in the cmc values obtained with several other techniques [ 41 , 42 , 43 ].…”

Glucose-Based Fluorinated Surfactants as Additives for the Crystallization of Membrane Proteins: Synthesis and Preliminary Physical–Chemical and Biochemical Characterization

“…25 The crude compounds were purified by flash chromatography to afford pure compounds 2a−c in 45−53% yields. The β-anomeric configuration of the three compounds was confirmed by 1 H and 13 C NMR spectra. The acetyl protective groups were then removed using a catalytic amount of MeONa in MeOH to afford the desired compounds 3a−c in 92−93% yields after silica gel flash chromatography purification.…”

“…19 F NMR (375 MHz, CDCl 3 ): δ −81.0, −113.9, −124.6, −125.9. 13 4′,4′,5′,5′,6′,6′,7′,7′,8′,8′,8′-Undecafluoro-4′-iodo-pentylβ-D-2,3,4,6-tetra-O-acetyl-glucopyranoside (3f). 3f was synthesized from compound 2f (1.50 g, 3.60 mmol), perfluoropropyliodide (1.60 g, 5.4 mmol), and 1M triethyl borane in hexane (0.7 mL, 0.72 mmol).…”

Methods for the solubilisation of membrane proteins: the micelle-aneous world of membrane protein solubilisation

“…However, recently there has been a drive towards developing completely novel detergents that confer, in particular, elevated protein stability, compared with classical detergents. Examples of these include; a new class of steroid-based pentasaccharides [ 6 ], fluorinated glucose and maltose-based detergents [ 7 , 8 ], innovative facial amphiphiles (FAs) [ 9 , 10 ], 1,3,5-triazine-cored detergents [ 11 ], disulfide containing amphiphiles [ 12 ] and modified neopentyl glycol based detergents that have undergone subsequent modification to further improve their characteristics [ 13 ] ( Figure 2 ).…”