7A9M

Ni-substituted Keggin silicotungstate with covalent bond to proteinase K

Summary for 7A9M

• Entry DOI: 10.2210/pdb7a9m/pdb
• Related: 7A9F 7A9K
• Descriptor: Proteinase K, SULFATE ION, Ni-substituted Keggin silicotungstate, ... (4 entities in total)
• Functional Keywords: keggin, polyoxometalate, additive, tungstate, protein binding
• Biological source: Parengyodontium album (Tritirachium album)
• Total number of polymer chains: 1
• Total formula weight: 34520.85

Authors

Breibeck, J.,Rompel, A. (deposition date: 2020-09-02, release date: 2021-10-06, Last modification date: 2024-10-23)

Primary citation

Breibeck, J.,Tanuhadi, E.,Gumerova, N.I.,Giester, G.,Prado-Roller, A.,Rompel, A.
Speciation of Transition-Metal-Substituted Keggin-Type Silicotungstates Affected by the Co-crystallization Conditions with Proteinase K.
Inorg.Chem., 60:15096-15100, 2021

PubMed Abstract: We report on the synthesis of the tetrasubstituted sandwich-type Keggin silicotungstates as the pure Na salts Na[(A-α-SiWO){Co(OH)(HO)}]·37HO () and Na[(A-α-SiWO){Ni(OH)(HO)}]·77.5HO (), which were prepared by applying a new synthesis protocol and characterized thoroughly in the solid state by single-crystal and powder X-ray diffraction, IR spectroscopy, thermogravimetric analysis, and elemental analysis. Proteinase K was applied as a model protein and the polyoxotungstate (POT)-protein interactions of and were studied side by side with the literature-known KNa[A-α-SiWO(OH){Co(OAc)}]·28.5HO () featuring the same number of transition metals. Testing the solution behavior of applied POTs under the crystallization conditions (sodium acetate buffer, pH 5.5) by time-dependent UV/vis spectroscopy and electrospray ionization mass spectrometry speciation studies revealed an initial dissociation of the sandwich POTs to the disubstituted Keggin anions HNa[SiWCoO] and HNa[SiWNiO] (, M = Co and Ni) followed by partial rearrangement to the monosubstituted compounds ( and ) after 1 week of aging. The protein crystal structure analysis revealed monosubstituted α-Keggin POTs in two conserved binding positions for all three investigated compounds, with one of these positions featuring a covalent attachment of the POT anion to an aspartate carboxylate. Despite the presence of both mono- and disubstituted anions in a crystallization mixture, proteinase K selectively binds to monosubstituted anions because of their preferred charge density for POT-protein interaction.

PubMed: 34529407
DOI: 10.1021/acs.inorgchem.1c02005

Experimental method

X-RAY DIFFRACTION (1.62 Å)