Schematic presentation of active sites from binary structures of S. enterica MTAN (SeMTAN). The structures were determined in the presence of MT-DADMe-ImmA (A), Homoc-DADMe-ImmA (B,C), BuT-DADMe-ImmA (D) and DiEGT-DADMe-ImmA (E,F). The direct and water mediated hydrogen bonds are shown as red dotted lines, determined using a maximum donor-acceptor distance of 3.35 Å. All the other residues are involved in the hydrophobic contacts (see also Table S1). The carbons, oxygens, nitrogens and sulfurs are colored in black, red, blue and yellow, respectively. The waters are shown as red balls. The W1 water is the active site nucleophilic water. The short water trail consists of W1, W2 and W3 waters. The 5´-alkylthio moieties of Homoc-DADMe-ImmA (B,C) and DiEGT-DADMe-ImmA (E,F) have different binding modes and hydrogen bonds in the binding pockets of SeMTAN homodimer. The figure was prepared with LigPlot (Laskowski and Swindells, 2011; Wallace et al., 1995).