FT- IR spectra of free HSA (blue) and HSA -virstatin complex (red) in D₂O in the range of 1720 to 1560 cm^−<b>1</b><b>.</b>

<p>FT- IR spectra of free HSA (blue) and HSA -virstatin complex (red) in D₂O in the range of 1720 to 1560 cm^−<b>1</b><b>.</b></p

Fluorescence quenching spectra of bis-ANS bound HSA in absence (top) and presence (the arrow indicating curves obtained with increasing concentration) of virstatin in phosphate buffer pH 7.2; [HSA] = 7.5 µM, [bis-ANS] = 5.0 µM and [virstatin] = 0.1 to 5.0 µM (with 10 increments of 0.1 µM, followed by another 5 of 1 µM).

<p>Fluorescence quenching spectra of bis-ANS bound HSA in absence (top) and presence (the arrow indicating curves obtained with increasing concentration) of virstatin in phosphate buffer pH 7.2; [HSA] = 7.5 µM, [bis-ANS] = 5.0 µM and [virstatin] = 0.1 to 5.0 µM (with 10 increments of 0.1 µM, followed by another 5 of 1 µM).</p

UV absorption spectra of virstatin before and after interacting with HSA in potassium phosphate buffer pH 7.2.

<p>The difference spectrum (complex – virstatin) is shown in the inset.</p

ITC data for the titration of (a) the N and (b) the B forms of HSA with virstatin.

<p>Flow of heat with time during the injection of the drug and the heat evolved per mole of added drug for each injection, shown at the top and the bottom, respectively.</p

Cartoon representation of HSA with the bound virstatin (red).

<p>Trp214 is shown in golden sticks. In (a) the N- and the C-termini of the polypeptide chain are shown as red and blue balls, respectively. (b) Close-up view of virstatin (N is in blue, O in red, H is in grey and the rest are C atoms) with two short contacts with Trp214 shown. (c) The cavity corresponding to site I with bound virstatin. The details of the relative positions of the neighboring residues (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0037468#pone-0037468-t004" target="_blank">Table 4</a>) are shown in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0037468#pone.0037468.s005" target="_blank">Figure S5</a>. The figures are made with PYMOL (<a href="http://www.pymol.org" target="_blank">http://www.pymol.org</a>).</p

Change in accessibilities of residues at binding sites I and II on binding different ligands.

a<p>Values for warfarin binding at Site I and ibuprofen binding at Site II are from <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0037468#pone.0037468-Varshney1" target="_blank">[53]</a>.</p>b<p>ΔASA = ASA(isolated) – ASA(complex), where ASA is the accessible surface area of a given residue. Only values >10 Ų are reported.</p

Urea induced unfolding of (a) N, (b) B and (c) F isomers of HSA in the absence (solid symbols) and the presence (open symbols) of virstain.

<p>The spectra overlaid along with the best-fit curves assuming a two-state model. F₃₄₀ and F₃₅₀ in the y-axis correspond to the fluorescence intensities at the respective wavelengths.</p

Secondary structural content of HSA upon interaction with virstatin in different molar ratios.

<p>Data were deconvoluted using CDNN software (<a href="http://bioinformatik.biochemtech.uni-halle.de/cdnn" target="_blank">http://bioinformatik.biochemtech.uni-halle.de/cdnn</a>).</p

Thermodynamic parameters derived from ITC measurements on the binding of virstatin and warfarin with different conformers of HSA.

<p>Values for warfarin are in square brackets.</p

Unfolding of different conformational isomers for HSA alone and HSA bound to virstatin.

<p>Based on data shown in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0037468#pone-0037468-g003" target="_blank">Figure 3</a>.</p