Fig. 5. Spectral properties of prodigiosin 2. (a) Fluorescence excitation and emission spectra of 2 in 20 mM HEPES, 100 mM NaCl, pH 7.5, 2% DMSO. (b and c) Reduction of fluorescence emission of 2 in the above buffer versus time passed from preparation of the solution. (d) The change in fluorescence emission intensity of 2 in the presence of His6-survivin. (e) The binding experiment of 5 μM of 2 and His6-survivin yielded a KD value of 11.5 ± 3.2 μM. (f) The comparison of the dissociation constant KD value of 1 and 2 with survivin. (g) The competition of 2 and a BIR domain ligand AKER (see ESI†).
