1.8.5.4 - 714310 1.8.5.4 crystal structures of the wild-type enzyme in complex with sodium selenide and gold(I) cyanide. Mechanism for the reduction of sulfides to elemental sulfur may involve nucleophilic attack of Cys356 on C4A atom of FAD or alternatively, an alternative anionic radical mechanism by direct electron transfer from Cys356 to the isoalloxazine ring of FAD 725835 1.8.5.4 crystallization in two crystal forms of hexagonal, prism shape and thin, elongated shape 714310 1.8.5.4 hanging drop vapor diffusion method, using 2.0 M ammonium sulfate and 4% (v/v) PEG 400 716746 1.8.5.4 hanging drop vapor diffusion method, using 2.2 M NH4H2PO4 and 100 mM Tris-HCl, pH 8.5 (final pH of the solution is 4.5), or 2.2 M NH4H2PO4/K2HPO4 at pH 4.5 714172 1.8.5.4 hanging drop vapor diffusion method, using 30% (w/v) PEG 600, 0.1 M bis-Tris pH 5.5, 0.1 M ammonium sulfate 713676 1.8.5.4 native or in complex with decylubiquinone, hanging drop vapor diffusion method, using 30% (w/v) polyethylene glycol 600, 0.1 M 2-[bis(2-hydroxyethyl)amino]-2-(hydroxymethyl)propane-1,3-diol (pH 5.5 or pH 6.5), 0.1 M magnesium sulfate, and 0.05% (w/v) n-dodecyl beta-D-maltoside 715911