posted on 2021-02-04, 20:06authored byMoheddine Wehbie, Kenechi Kanayo Onyia, Florian Mahler, Aline Le Roy, Anais Deletraz, Ilham Bouchemal, Carolyn Vargas, Jonathan Oyebamiji Babalola, Cécile Breyton, Christine Ebel, Sandro Keller, Grégory Durand
Two new surfactants, F5OM and F5DM, were
designed as partially fluorinated analogues of n-dodecyl-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, isothermal titration
calorimetry, dynamic light scattering, small-angle X-ray scattering,
and analytical ultracentrifugation. 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 F5OM to 0.3–0.5
mM for F5DM, and micellization was mainly entropy-driven
at 25 °C. Close to their respective cmc, the micelle sizes were
similar for both surfactants, that is, 7 and 13 nm for F5OM and F5DM, 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 directly from Escherichia coli membranes. They were found more efficient than the commercial fluorinated
detergent F6H2OM 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 was 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 F6OM. Together, these findings indicate both
extracting and stabilizing properties of the new maltose-based fluorinated
surfactants, making them promising tools in MP applications.