Skip to main content
. 2020 Jun 12;15(6):e0234468. doi: 10.1371/journal.pone.0234468

Fig 2. Surface plasmon resonance (SPR) shows dose-dependent binding of human SUMO1 to fisetin, quercetin, and isoliquiritigenin.

Fig 2

(A-H) Candidate ligands predicted to bind to recombinant human SUMO1 from the SPR primary screen were tested for dose-dependent binding saturation in a SPR secondary screen. SPR sensograms are shown with fitted curves (insets), performed by fitting resonance units (RU) vs. concentration plots using the classical one-site hyperbola binding equation in GraphPad Prism7. (A) Fisetin, (B) Quercetin, and (C) Isoliquiritigenin exhibited binding that approached saturation with reasonable Kd values. (D) Butein, (E) Naringenin, (F) Pinoquercetin, (G) Quercetin 3-β-D-glucoside, and (H) 3’,4’,7-Trihydroxyisoflavone failed to exhibit saturation binding. (I) Binding of fisetin to human SUMO1 was characterized further using an extended range of concentrations, yielding an average Kd value of 227.8 ± 19.5 μM. (J) Fisetin failed to bind to bovine ubiquitin. The fitted curve indicates an average of six replicates. Error bars for fitted curves in (I) and (J) correspond to a 95% confidence interval.