FIG. 5.

Chemical cross-linking of SsuE and SsuD. (A) structure of the trifunctional cross-linker reagent (ProFound Label Transfer Sulfo-SBED). The reagent contains an amine reactive site, a photoreactive arylazide, a biotin label, and a cleavable disulfide bond. (B) Silver-stained SDS-PAGE (10% acrylamide) from cross-linking reactions. Lanes 1 and 6, protein markers; lane 2, SsuE and SsuD proteins; lane 3, treated SsuE; lane 4, cross-linked SsuE and SsuD; lane 5, DTT-treated cross-linked SsuE and SsuD; lane 7, native SsuE and SsuD. The samples were mixed with nondenaturing and nonreducing sample buffer except for protein markers (lanes 1 and 6) and SsuE and SsuD proteins (lane 2).