Figure 2.

(A) Conjugation of SUMO to a fluorescent substrate peptide is inhibited by macrophilone analogue 4. The inhibitory activity of 4 is abolished by addition of the antioxidant NAC to the assay mixture. GA = ginkgolic acid, 30 μM (positive control). (B) Silver stained gel indicating analogue 4 induces E1−E2 cross-linking by formation of a disulfide bond between the E1 subunit Uba2 and the E2 enzyme Ubc9. This cross-linking does not occur with 100 μM 4 in the presence of 100 mM DTT. Both 1 mM H₂O₂ and 10 μM β-lapachone are included as positive controls. (C) Detection of ROS in A549 cells by fluorescence of CM-H2DCFDA.