Figure 6
Biophysical studies of the Csd4–Csd5 or the Csd5–dipeptide interaction in solution. (a) SPR experiments with immobilized Csd4 and Csd5 as an analyte at different concentrations (0.25, 0.50, 1.00 and 2.00 µM) are shown as grey-coloured traces. Black traces show the corresponding binding-model curves. (b) At the same concentration of Csd5 (2.00 µM), the interaction between Csd4 and Csd5 (`no treatment') was lost upon treatment of the Csd4-immobilized chip with 20 mM EDTA to remove intrinsic metal ions (`after EDTA treatment'). Retreatment of the EDTA-treated Csd4-immobilized chip with 5 mM calcium chloride recovered the binding between two proteins (`after CaCl2 treatment'). All sensorgrams were obtained by subtracting the nonspecific binding of the analyte to the BSA-immobilized chip. (c) Fluorescence polarization binding assay using an FITC-labelled dipeptide against increasing concentrations of Csd5. |