» Sign in / Register

XP Screens - Intelligent Crystal Screens

Upgraded with the Anderson−Evans polyoxotungstate [TeW6O24]6− (TEW) as universal additive, the XP Screens promote protein crystallization even for most challenging targets and improve diffraction quality of protein crystals[1]. Its potential has been shown in the new protein structures of aurone synthase from Coreopsis grandiflora[2-4] (PDB code: 4Z12, 4Z13) and mushroom tyrosinase PPO4 from Agaricus bisporus[6,7] (PDB code: 4OUA). The model protein lysozyme crystallized into a new crystal form[5] (PDB code: 4PHI).
The XP Screens are TEW-optimized JBScreen Basics: 96 of the most prominent crystallization conditions complemented with TEW as "glue" for protein molecules.


  • is highly soluble in aqueous solutions and stable over a wide pH range
  • has a high negative charge that links positively charged protein surface regions, the electrostatic spacer effect prevents steric interference between protein molecules
  • provides a valuable anomalous signal for phasing
  • can act as linker in various orientations (pictured below) and even structurally adapt to fit into the protein molecule[3]
  • is able to induce heterogeneous crystallization, e.g. two different protein forms in one single crystal[6]

Protein-protein bridging by TEW in different orientations
Image from [1], used by courtesy of Prof. Annette Rompel, University of Vienna, Austria


BIOZ Product Citations

Please click the arrow on the right to expand the citation list. Click publication title for the full text.

Selected Literature Citations of XP Screen

  • Sobala et al. (2020) Structure of human endo-α-1,2-mannosidase (MANEA), an antiviral host-glycosylation target. PNAS 117 (47):29595.
  • Ames et al. (2020) Identifying a Molecular Mechanism That Imparts Species-Specific Toxicity to YoeB Toxins. Front Microbiol 11:959.

References / Recommended Literature

[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) Aurone synthase is a catechol oxidase with hydroxylase activity and provides insights into the mechanism of plant polyphenol oxidases. Proc. Natl. Acad. Sci. 113:E1806.
[3] 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.
[4] Molitor et al. (2015) Crystallization and preliminary crystallographic analysis of latent, active and recombinantly expressed aurone synthase, a polyphenol oxidase, from Coreopsis grandiflora. Acta Cryst. F 71:746.
[5] Bijelic et al. (2015) Hen Egg-White Lysozyme Crystallisation: Protein Stacking and Structure Stability Enhanced by a Tellurium(VI)-Centred Polyoxotungstate. ChemBioChem 16:233.
[6] Mauracher et al. (2014) Latent and active abPPO4 mushroom tyrosinase cocrystallized with hexatungstotellurate(VI) in a single crystal. Acta Cryst. D 70:2301.
[7] Mauracher et al. (2014) Crystallization and preliminary X-ray crystallographic analysis of latent isoform PPO4 mushroom (Agaricus bisporus) tyrosinase. Acta Cryst. F 70:263.