An EXAFS Approach to the Study of Polyoxometalate–Protein Interactions: The Case of Decavanadate–Actin

Abstract

EXAFS and XANES experiments were used to assess decavanadate interplay with actin, in both the globular and polymerized forms, under different conditions of pH, temperature, ionic strength, and presence of ATP. This approach allowed us to simultaneously probe, for the first time, all vanadium species present in the system. It was established that decavanadate interacts with G-actin, triggering a protein conformational reorientation that induces oxidation of the cysteine core residues and oxidovanadium (V) formation. The local environment of vanadium's absorbing center in the [decavanadate-protein] adducts was determined, a V-S coordination having been verified experimentally. The variations induced in decavanadate's EXAFS profile by the presence of actin were found to be almost totally reversed by the addition of ATP, which constitutes a solid proof of decavanadate interaction with the protein at its ATP binding site. Additionally, a weak decavanadate interplay with F-actin was suggested to take place, through a mechanism different from that inferred for globular actin. These findings have important consequences for the understanding, at a molecular level, of the significant biological activities of decavanadate and similar polyoxometalates, aiming at potential pharmacological applications.

Vanadium in Biological Action: Chemical, Pharmacological Aspects, and Metabolic Implications in Diabetes Mellitus

“…At pH of 6 or below and concentrations of 0.2 mM and above, the vanadium decamer (decavanadate) is formed and it is the predominant species; however, a mixture of decavanadate, monoprotonated and diprotonated decavanadate, and small amounts of tetravanadate as well as free vanadate are present. Furthermore, the protein interplay into cell leads to decavanadate stabilization, thus suggesting that V10 interacts with specific locations within these (e.g., alkaline phosphatase, adenylate kinase, P-type ATPases, ABC ATPases, F-actin, myosin ATPase, and ribonuclease) protecting the decameric species against conversion to the structurally and functionally distinct lower oxovanadates (vanadium monomer, dimer, or tetramer) [86,87]. Unlike other vanadate oligomers, this oligomer undergoes successive protonation reactions with an increase in acidity, going from a charge of − 6 to − 3, being the − 4 and − 5 anions the predominant forms.…”

Removal Process of Structural Oxygen from Tetrahedrons in Muscovite during Acid Leaching of Vanadium-Bearing Shale

“…The shifting of these hydroxyl groups reduces the stability of the octahedrons and benefits the release of Al/V from the octahedrons. Meanwhile, the removal of the first structural water exposes the cations (Si/Al) of the tetrahedrons and provides more active sites for the attack of anions, like SO 4 2− and F − , in the acid solution. During the continuous removal of structural O and Si/Al from the tetrahedral sheets, the original stable framework of tetrahedral sheets gradually breaks.…”

“…Vanadium (V), due to its polyvalence, has been applied in various fields such as catalysis, photochemistry, material science, and medicine [1][2][3], and the toxicology of some vanadium species has also attracted extensive attention [4]. In China, vanadium extraction from black shales, a unique and significant vanadium resource, has developed into a systematic and diversified process [5,6].…”

Tuning the interactions of decavanadate with thaumatin, lysozyme, proteinase K and human serum proteins by its coordination to a pentaaquacobalt(ii) complex cation

“…36 Some artificial vanadium compounds, on the other hand, exhibit insulin mimetic properties, antitumor activity, antibacterial activity or anti-HIV activity. [35][36][37][38][39] Specifically decavanadate itself has also been studied with respect to many biological aspects, [40][41][42][43] and it was shown that V 10 binds to several proteins such as actin, 44 myosin, 45 ion pump Ca 2+ -ATPase, 46 bovine serum albumin and gelatine, 47 and microtubule-associated proteins. 48 Protein crystallography revealed the presence of V 10 in the crystal structures of acid phosphatase A (F. tularensis), 49 human activated receptor tyrosine kinase, 50 NTPDase1 (L. pneumophila), 51 NTPDase1 (R. norvegicus), 52 and human TRPM4 channel.…”