Fig 3. Viscosity of the folded and unfolded protein.

A) Bulk viscosity variations with increasing concentration of BSA (square markers): in a pure buffer (blue markers), and a buffer with 7 M of urea (red markers). These measurements are repeated for 50 μL volume in the meniscus configuration (circles markers). The experiments were carried out at T = 25°C and T = 26°C in the meniscus and the conventional configurations, respectively. B) The full data set for several urea concentrations are fitted to Eq 7 using the hydrodynamic radius as adjustable parameter. C) A full set of solution viscosities is obtained from direct measurements of ω_r (Eq 6) through a Gaussian fit to the maximum PSD. Symbols represent the experimental data and lines represent the corresponding fit. The color scale, at the right hand side of panel C, represents the urea concentration in panels B and C. Note that $\varphi =c·N_a\frac{4}{3}\pi R_H^3$, with c in mM.