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Figure 6
POM (TEW) binding site. Colour code: L-TYR, blue; A-TYR, purple; O atoms, red; Te atom, grey, W atoms, black; water molecules, cyan; hydrogen bonds, dashed black lines; positively charged coulombic surface, blue; negatively charged coulombic surface, red. (a) POM-binding (L-TYR) site B is located at the tip (start of α-helix α5) of the conical-shaped main core. The polyoxoanion lies on a twofold axis (C2) embedded by two opposing HKKE motifs (L-TYR and L-TYR C2). (b) Image of two different views of the one-sided POM-binding site B with the respective electron density indicated by a grey mesh (2mFomFc, 0.40 e Å−3, 1 r.m.s.d.) and all possible hydrogen bonds outlined. (c) Coulombic surface image of two opposing asymmetric units (heterodimer, A-TYR/L-TYR abPPO4) sharing two polyoxoanions on a twofold axis. This image illustrates how the POM acts as a conjunction linking two otherwise repulsive surfaces. (c) Image section of crystal packing displaying a sandwich-like constitution (protein layer–POM layer–protein layer).

Journal logoBIOLOGICAL
ISSN: 1399-0047
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