Figure 5. Size-exclusion chromatography of PR_MDR treated with P27 and the corresponding fluorescent spectra for the dimeric and monomeric forms.

PR_MDR (1 μM final concentration) was incubated for 16 h at 37 °C in 150 mM ammonium acetate buffer containing 100 μg · ml⁻¹ BSA with P27 at 25 μM. Following incubation, 8 μl of the PR was sampled and analysed by size-exclusion chromatography. (A) PR_MDR was detected by fluorescence by excitation at 280 nm and emission at 350 nm and (B) by MS in SIM mode for the PR_MDR-specific ion (m/z 1086, 10⁺). (C) The fluorescent emission spectra λ_em from 325–375 nm were obtained at the peak apex for each peak using reference spectra at 10.2 and 12 min. The spectra for the dimer (D) (solid line, λ_max = 346 nm) and the monomer (M) (dashed line, λ_max = 352 nm) are shown. Rel Ab, relative ion abundance; RFU, relative fluorescence units.