Polyoxometalates: more than a phasing tool in protein crystallography

Abstract

Protein crystallography is the most widely used method for determining the molecular structure of proteins and obtaining structural information on protein–ligand complexes at the atomic level. As the structure determines the functions and properties of a protein, crystallography is of immense importance for nearly all research fields related to biochemistry. However, protein crystallography suffers from some major drawbacks, whereby the unpredictability of the crystallization process represents the main bottleneck. Crystallization is still more or less a ‘trial and error’ based procedure, and therefore, very time and resource consuming. Many strategies have been developed in the past decades to improve or enable the crystallization of proteins, whereby the use of so-called additives, which are mostly small molecules that make proteins more amenable to crystallization, is one of the most convenient and successful methods. Most of the commonly used additives are, however, restricted to particular crystallization conditions or groups of proteins. Therefore, a more universal additive addressing a wider range of proteins and being applicable to a broad spectrum of crystallization conditions would represent a significant advance in the field of protein crystallography. In recent years, polyoxometalates (POMs) emerged as a promising group of crystallization additives due to their unique structures and properties. In this regard, the tellurium-centered Anderson–Evans polyoxotungstate [TeW6O24]6− (TEW) showed its high potential as crystallization additive. In this lecture text, the development of POMs as tools in protein crystallography are discussed with a special focus on the so far most successful cluster TEW.Electronic supplementary materialThe online version of this article (10.1007/s40828-018-0064-1) contains supplementary material, which is available to authorized users.

Polyoxometalates in solution: speciation under spotlight

“…In rare cases where the solution chemistry is presented in literature, the solution details are often not of the main interest for the authors, and are described only in the supplementary materials. The rapidly growing number of POMs application in solution, especially their catalytic 7 and biological ones, [8][9][10][11] entails the need for a deeper understanding and analysis of the fundamental relationship between POM's structural behavior in the solid state and in solution. This is currently an acute drawback, often leading to an incorrect interpretation and erroneous determination of structure-activity relationships.…”

Size-Exclusion Mechanism Driving Host–Guest Interactions between Octahedral Rhenium Clusters and Cyclodextrins

“…Actually, some ionic species has been even identified as "superchaotrope" leading to highly stable supramolecular aggregates with organic matter such as macrocyclic hosts, 15,17,18 lipid surfaces, 19 membranes, 20 or proteins. [21][22][23][24] The control of such self-assembly process recently emerged as an innovative route to hierarchical hybrid supramolecular assemblies. 13 Octahedral rhenium cluster complexes due to their antitumoral, anti-bacterial, photoluminescent, redox and X-ray contrast properties are appealing inorganic species for applications in biology and medicine.…”

Aluminum-Substituted Keggin Germanotungstate [HAl(H2O)GeW11O39]4–: Synthesis, Characterization, and Antibacterial Activity

“…These features make them attractive materials in a wide range of fields like catalysis, 2 electrochemistry, 3 magnetochemistry, 4 and biological chemistry 5 including protein crystallography. 6 Among the variety of POMs reported to date, Keggin-type POMs represent the largest family. The incorporation of metal ions into the vacant site(s) of lacunary POMs derived from their plenary counterparts upon controlled hydrolysis of the framework is one of the most powerful synthetic approaches used to encapsulate well-defined metal sites with heteroatoms ranging from 3d transition metals over lanthanides to main-group III elements.…”