(A) n-dodecyl-β-D-maltoside (DDM); (B)
n-undecyl-β-D-maltoside (UM); (C)
n-Decyl-β-D-maltoside (DM); (D)
4-Cyclohexyl-1-butyl-β-D-maltoside (CYMAL-4). All anisotropy
measurements were conducted out in 200 mM NaCl, 50 mM HEPES, pH 7.4, and at room
temperature. The anisotropy data were recorded by adding overnight detergent-refolded
protein to a bath of varying detergent concentration, but keeping the final protein
concentration at 28 nM. Starting detergent concentrations were above the CMC. Thereafter,
they were reduced at concentrations below the CMC (Experimental Methods).
Time-dependent anisotropy measurements were conducted directly after dilution of the
refolded protein sample at respective detergent concentration. Vertical bars represent the
magnitudes of the CMC and Kd of the PDCs of varying
isoelectric point of the proteins. The horizontal dashed bar represents the minimum
anisotropy value, r1 = ~0.16, obtained with FhuA
ΔC/5L in 6 M Gdm-HCl (Table 3). This
anisotropy value corresponds to the most rotationally diffusive FhuA
ΔC/Δ5L.