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XP Screens: Crystal Screening with TEW - The Protein Crystal Glue

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The Anderson-Evans Polyoxotungstate [TeW6O24]6- (TEW) is a universal and flexible crystallization additive[1] that is integrated in our XP Screens. It was shown to improve crystal quality and resolution by:

  • binding to the protein surface and forming tight crystal lattice contacts[3-7]
  • acting as linker in various orientations and thereby creating either smaller (PDB: 4OUA) or larger (PDB: 4PHI) protein-protein distances[3,4]
  • heterogeneous crystallization of two different protein forms in one single crystal (PDB: 4OUA)[4]
  • inducing new crystal forms with access to the active site (PDB: 6ZDK, 6ZDL, 6ZFA)[5]
  • covalently binding and structurally adapting to fit into protein molecules (PDB: 4Z12, 4Z13)[2]
Covalent binding of W to carboxylic oxygen atoms of glutamic acid (cgAUS1, PDB code: 4Z12, 4Z13)[2]
Figure 1: Covalent binding of Tungsten to carboxylic oxygen atoms of glutamic acid (PDB: 4Z12, 4Z13).[2] Figure from [1].

TEW Properties

Chemical structure of TEW, Figure from [1]

  • Centrosymmetric, inorganic cluster
  • Disk-shaped ion [TeW6O24]6-
  • Dimensions: 9 x 9 x 3 Å3
  • MW: 1.615 g/mol (ion)
  • Highly soluble in aqueous solutions (100 mM) and stable over a wide pH range
  • 6 tungsten atoms provide strong anomalous scattering signal for phasing

Figure 2 (right): Chemical structure of TEW. Figure from [7].

Advantages of XP Screens

  • Convenient initial screening with up to 10 mM TEW
  • Tight crystal contacts
  • Improved crystal quality and resolution
  • New crystal forms (e.g to provide access to binding pockets)
  • Direct phasing
XP Screens scheme
Figure taken from [1]

The XP Screen

The XP Screen is a convenient initial screen that has successfully induced protein crystallization with low TEW concentrations such as 1 mM[5,6]. In some cases however, higher concentration of 5 or 10 mM TEW are needed.

The XP Up Screen

The XP Up Screen is an upgrade of the well-established XP Screen. It contains 96 of the most prominent screening solutions that are long-term stable in the presence of up to 10 mM TEW.

Product Cat. No. Description
XP Screen CS-350 96 screening conditions with 1 mM TEW
XP Up Screen CS-351 96 screening conditions to be upgraded with up to 10 mM TEW
Anderson-Evans polyoxotungstate (TEW) X-TEW-5 Additive for optimization

Questions or inquiries?

Christin Reuter

E-mail Christin for technical inquiries or further information: xtals@jenabioscience.com


[1] Bijelic et al. (2017) Ten Good Reasons for the Use of the Tellurium-Centered Anderson-Evans Polyoxotungstate in Protein Crystallography. Acc. Chem. Res. 50:1441.
[2] Molitor et al. (2016) In situ formation of the first proteinogenically functionalized [TeW6O24O2(Glu)]7- structure reveals unprecedented chemical and geometrical features of the Anderson-type cluster. Chem. Commun. 52:12286.
[3] Bijelic et al. (2015) Hen Egg-White Lysozyme Crystallisation: Protein Stacking and Structure Stability Enhanced by a Tellurium(VI)-Centred Polyoxotungstate. ChemBioChem 16:233.
[4] Mauracher et al. (2014) Latent and active abPPO4 mushroom tyrosinase cocrystallized with hexatungstotellurate(VI) in a single crystal. Acta Cryst. D 70:2301.
[5] Sobala et al. (2020) Structure of human endo-α-1,2-mannosidase (MANEA), an antiviral host-glycosylation target. PNAS 117 (47):29595.
[6] Ames et al. (2020) Identifying a Molecular Mechanism That Imparts Species-Specific Toxicity to YoeB Toxins. Front. Microbiol. 11:959.
[7] Mac Sweeney et al. (2018) The crystallization additive hexatungstotellurate promotes the crystallization of the HSP70 nucleotide binding domain into two different crystal forms. PLOS one 13 (6): e0199639.