Fig. 2. Covalent binding of GluTEW resulting in a novel polyoxotungstate. (a) Left: The carboxylic oxygen atoms of Glu157 bind covalently to two tungsten atoms of hexatungstotellurate(vi) (W–O distance ∼2.35 Å), while a reduction of the coordination number of two tridentate oxygen atoms occurs. A partially 2Fo–Fc electron density map (blue mesh) contoured at 1.0σ is shown. Right: Structure comparison of TEW, GluTEW and the polyoxomolybdate [Ag₂IMo₆O₂₄]^3–.¹⁴ (b) Analysis of GluTEW–protein interactions using LigPlot⁺.¹⁵ Left: Direct TEW–cgAUS1 hydrogen interactions. Right: Water-mediated TEW–cgAUS1 hydrogen interactions. Color code: (a) ball-and-stick presentation: carbon, light-cyan; nitrogen, blue; oxygen, red; tungsten, black; tellurium, grey. Polyhedra presentation: carbon, green; nitrogen, blue; oxygen, red; tungsten, marine-blue; tellurium, light-brown; silver, gold; molybdenum, forest-green; iodine, purple. (b) Small sphere presentation: carbon, green; nitrogen, blue; oxygen, red; tungsten, black; tellurium, grey; water molecules, light-cyan.