Hybrid Fluorinated and Hydrogenated Double-Chain Surfactants for Handling Membrane Proteins

Two hybrid fluorinated double-chain surfactants with a diglucosylated polar head were synthesized. The apolar domain consists of a perfluorohexyl main chain and a butyl hydrogenated branch as a side chain. They were found to self-assemble into small micelles at low critical micellar concentrations, demonstrating that the short branch increases the overall hydrophobicity while keeping the length of the apolar domain short. They were both able to keep the membrane protein bacteriorhodopsin stable, one of them for at least 3 months

Partial-specific volumes obtained for different protein samples.

a<p>from amino acid composition predicted in SEDFIT;</p>b<p>reported in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0026221#pone.0026221-Jossang1" target="_blank">[80]</a>;</p>c<p>stock concentrations were determined spectrophotometrically using extinction coefficients as noted in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0026221#s2" target="_blank">Materials and Methods</a>;</p>d<p>average signal of sedimentation boundary <i>vs</i> average root-mean-square deviation of global fit;</p>e<p>based on 68% confidence level.</p

Global density variation SV analysis of the interference optical data from the BSA sample.

<p>The sets of panels present the data in (A) H₂O, (B) 50% H₂¹⁸O, and (C) 90% H₂¹⁸O based buffer. The presentation is analogous to that in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0026221#pone-0026221-g001" target="_blank">Figure 1</a>. Rmsd of the fit was 0.00346 fringes (A), 0.00337 fringes (B), and 0.00416 fringes (C). The best-fit <i>c</i>(<i>s</i>) distribution from this analysis is shown in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0026221#pone-0026221-g008" target="_blank">Figure 8</a>, and the projections of the error surface in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0026221#pone-0026221-g009" target="_blank">Figure 9</a>.</p

Interference optical data from the same sample as in <b>Figure 1</b>, in the same representation.

<p>Rmsd values are 0.00230 fringes (A), 0.00289 fringes (B) and 0.00312 fringes (C).</p

Density and viscosity values measured for PBS solutions containing different fractions of H₂¹⁸O.

(a)<p>H₂¹⁸O fraction by volume, using the 97% isotopically enriched heavy-oxygen water as a reference.</p

Global density variation SV analysis of the phosphorylase B sample recorded with the absorbance data at 280 nm.

<p>The sets of panels present the data in (A) H₂O, (B) 50% H₂¹⁸O, and (C) 90% H₂¹⁸O based buffer. For each set of panels, the measured data (corrected for the time-invariant noise contributions) are shown as solid lines, and the global best-fit profiles are shown as thin dotted lines (virtually superimposed to the data). Higher color temperatures indicate later times. Below are the residuals bitmap (a 2d grey-scale representation of residual values with time plotted vertically and radius horizontally <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0026221#pone.0026221-Dam1" target="_blank">[69]</a>) and the residuals of the fit, with rmsd of 0.00365 OD (A), 0.00411 OD (B), and 0.00380 (C). In the presence of H₂¹⁸O, fewer scans were included into the analysis in order to achieve similar numbers of total scans representing the sedimentation process. The best-fit <i>c</i>(<i>s</i>) distribution from this analysis is shown in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0026221#pone-0026221-g002" target="_blank">Figure 2</a>.</p

Projections of the error surface as a function of

<p><b>-values.</b> Shown are the relative increase in the χ² of the fit as a function of different fixed -values, for each value freely adjusting all other unknown parameters <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0026221#pone.0026221-Bevington1" target="_blank">[79]</a>. Data are shown for the absorbance IgG data set (black) and the interference data set from the BSA sample (blue). For each, the dashed line shows the increase predicted by F-statistics for the 68% confidence level <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0026221#pone.0026221-Bevington1" target="_blank">[79]</a>. This critical increase of χ² is lower for the BSA data set due to the significantly larger number of data points.</p

Sedimentation coefficient distribution for the global analysis of the BSA sample (<b>Figure 7</b>).

<p>Relative scaling factors and were 0.978 and 0.977, indicating slightly different best-fit loading concentrations.</p

Sedimentation coefficient distribution for the global analysis of the absorbance data from the phosphorylase sample (<b>Figure 1</b>).

<p>Relative scaling factors and were 1.039 and 1.136 (see Eq. 19), indicating slightly different best-fit loading concentrations.</p

Sedimentation coefficient distribution for the global analysis of the absorbance data from the IgG sample (<b>Figure 4</b>).

<p>Relative scaling factors and were 0.955 and 1.034, indicating slightly different best-fit loading concentrations.</p