Chemical shift perturbation upon variation in FGF2 concentrations.

<p>A. HSQC spectra of heparin column purified FGF2 of 1.5 mM (purple), 1.1 mM (Blue), 0.55 mM (green), 0.275 mM (orange) and 0.137 mM (red). B. HSQC spectra of ion-exchange column purified FGF2 of 1 mM (black) and 0.125 mM (red). Chemical shift difference is only observed in the heparin-column purified FGF2 and the difference is analyzed by the combined chemical shift perturbation, [(Δδ_NH² + Δδ_N²/25)/2]^1/2. C. Chemical shift perturbation of the heparin-column purified FGF2 is between 0.137 mM and 0.55 mM and (D) the residues with perturbation larger than the threshold value of 0.01 ppm were highlighted on the FGF2 structure (PDB code: 1BLA) with yellow spheres. E. Chemical shift perturbation of the heparin-column purified FGF2 between 0.137 mM and 1.5 mM and (F) the residues with perturbations larger than the threshold values of 0.012, 0.015 and 0.02 ppm were pointed out FGF2 structure as yellow, orange and red spheres, respectively where the radius of sphere reflects the quantity of chemical shift perturbation. The proposed two dimer interfaces are indicated by dash lines.