Fluorinated Detergents

Fluorinated Detergents

Introduction

Membrane proteins require a membrane-mimetic environment to keep them both soluble and active during in vitro studies, which is typically accomplished with the aid of detergents. However, many membrane proteins will become unstable and lose their native structures and functions when solubilised in detergents. This has prompted efforts to develop reagents that are milder than conventional hydrogenated detergents among which fluorinated detergents appear particularly promising. Fluorinated detergents refer to the hydrogen atoms in alkyl chains of detergents structure are replaced by fluorine, in other words, the chemical structure of fluorinated detergents resembles those of classical hydrogenated detergents, but their hydrophobic tails contain fluorine atoms. Owing to the weak affinity of fluorinated chains for hydrogenated ones and to the larger volume of fluorocarbons as compared with hydrocarbons, fluorinated detergents are less destabilizing toward membrane proteins than hydrogenated ones because they hardly compete with stabilizing protein-protein and protein-lipid/hydrophobic cofactor interactions^[1]. Until now, although fluorinated detergents are far from being compared with hydrogenated detergents in terms of quantity and application, several series of fluorinated surfactants have been synthesized over the past 20 years and successfully applied to the study of membrane proteins.

Applications

Numerous applications of fluorinated detergents have already been reported. These include solubilization of membrane proteins, stabilization of membrane proteins, crystallization of membrane proteins, in vitro synthesis of membrane proteins and others.

Solubilization of Membrane Protein: Earlier neutral fluorinated detergents were not able to solubilize membrane proteins from membrane lipid bilayers. But that's a thing of the past. Faugier et al. reported the use of a fluorinated lactobionamide-based detergent named FLAC6 for functional study of membrane proteins. FLAC6 consists of a lactobionamide polar head group attached through an amide bond to a C9 alkyl tail, with six perfluorinated terminal carbon atoms. They demonstrated that FLAC6 efficiently solubilized three membrane proteins i.e. the native adenosine receptor A2AR, a G protein-coupled receptor, and two native transporters AcrB and BmrA, showing a remarkable membrane proteins solubilization ability^[2].

Fig. 1. Chemical structure of fluorinated detergent FLAC6.

Stabilization of Membrane Proteins: Fluorinated detergents have shown a great potential for the stabilization of various membrane proteins. For example, Polidori et al. have synthesized two novel fluorinated maltose-based detergents having the same theoretical hydrophobicity as the common detergent dodecyl maltoside but bearing a sparingly fluorinated chain (perfluoroethyl (F₂H₉) or a perfluorobutyl (F₄H₅)) and then evaluated their biochemical use for membrane-protein stabilization. Intriguingly, the detergent carrying a perfluorobutyl (F₄H₅) tip trumps nonfluorinated dodecyl maltoside in conferring extraordinary long-term functional and colloidal stability to the membrane protein bacteriorhodopsin^[3].

Fig. 2. Chemical structure of fluorinated maltose-based detergents.

Crystallization of Membrane Proteins: Mixtures of fluorinated detergents and hydrogenated detergents lead to various micellar organizations. It is thus expected that fluorinated detergents are expected to play a role in membrane protein crystallization. Wehbie et al. confirmed it. They synthesized six glucose-based fluorinated detergents with a glucose polar head group and whose alkyl chain was varied in length, from six to eight carbon atoms. Then the potency of one of the detergents, F₃H₅-β-Glu, to act as an additive for the crystallization of AcrB membrane protein was evaluated in detergent mixtures with n-dodecyl-β-D-maltopyranoside (DDM). The results indicated that F₃H₅-β-Glu as additives improved the crystallization of AcrB membrane protein, further showing these novel glucose-based fluorinated detergents should be regarded as potential additives that could be included in screening kits used in crystallization^[4].

Fig. 3. Comparison of crystallization effect of AcrB membrane protein
without (left) and with (right) glucose-based fluorinated detergents.

Others: In addition, fluorinated detergents can also be used in in vitro synthesis of membrane proteins, inserting membrane proteins into preformed membranes, and refolding membrane proteins.

As a leading company in the field of organofluorine chemistry, Alfa Chemistry has deep research experience in the field of fluorinated detergents. We offer a wide range of fluorinated detergents which show good application potential in solubilization, stabilization and crystallization of membrane proteins. If you cannot find the desired product, Alfa Chemistry also offers you with custom synthesis service. If necessary, please don't hesitate to contact us.

References

1. Boussambe G. N. M., et al. Fluorinated diglucose detergents for membrane-protein extraction[J]. Methods, 2018, 147: 84-94.
2. Faugier C., et al. Lactobionamide-based fluorinated detergent for functional and structural stabilization of membrane proteins[J]. Methods, 2020, 180: 19-26.
3. Polidori A., et al. Sparingly fluorinated maltoside-based surfactants for membrane-protein stabilization[J]. New Journal of Chemistry, 2016, 40(6): 5364-5378.
4. Wehbie M., et al. Glucose-Based Fluorinated Surfactants as Additives for the Crystallization of Membrane Proteins: Synthesis and Preliminary Physical–Chemical and Biochemical Characterization[J]. ACS omega, 2021, 6(38): 24397-24406.