Vanadate oligomers interaction with phosphorylated myosin,
Tiago, T., Aureliano M., Duarte R. O., and Moura J. J. G.
, Inorganica Chimica Acta, Nov 15, Volume 339, p.317-321, (2002)
AbstractUsing a myosin preparation containing endogenous myosin light-chain (LC2) kinase and phosphatase and calmodulin, i.e. near physiological ones, the interaction of vanadate oligomers with phosphorylated myosin was evaluated. Decavanadate or metavanadate solutions (2-15 mM total vanadate) did not prevent the phosphorylation state of the regulatory myosin lightchain, as observed by urea-polyacrylamide gel electrophoresis. The relative order of line broadening upon protein addition, reflecting the interaction of the vanadate oligomers with phosphorylated myosin, was V10 > V-4 > V-1 = 1 whereas, no changes were observed for monomeric vanadate. In the presence of ATP, V-1 signal was shifted upfield 2 ppm and became broadened, while V4 signal became narrowed. Moreover, a significant increase in myosin ATPase inhibition (60%) was observed when decameric vanadate species were present (1.4 mM). It is concluded that, under conditions near physiological ones, decameric vanadate differs from vanadate oligomers present in metavanadate solutions due to its strong interaction with the phosphorylated enzyme and myosin ATPase inhibition. Besides, ATP decreases the affinity of myosin for tetravanadate, induces the interaction with monomeric vanadate, whereas it does not affect decameric vanadate interaction. (C) 2002 Elsevier Science B.V. All rights reserved.
Vanadium distribution, lipid peroxidation and oxidative stress markers upon decavanadate in vivo administration,
Soares, S. S., Martins H., Duarte R. O., Moura J. J., Coucelo J., Gutierrez-Merino C., and Aureliano M.
, J Inorg Biochem, Jan, Volume 101, Number 1, p.80-8, (2007)
AbstractThe contribution of decameric vanadate species to vanadate toxic effects in cardiac muscle was studied following an intravenous administration of a decavanadate solution (1mM total vanadium) in Sparus aurata. Although decameric vanadate is unstable in the assay medium, it decomposes with a half-life time of 16 allowing studying its effects not only in vitro but also in vivo. After 1, 6 and 12h upon decavanadate administration the increase of vanadium in blood plasma, red blood cells and in cardiac mitochondria and cytosol is not affected in comparison to the administration of a metavanadate solution containing labile oxovanadates. Cardiac tissue lipid peroxidation increases up to 20%, 1, 6 and 12h after metavanadate administration, whilst for decavanadate no effects were observed except 1h after treatment (+20%). Metavanadate administration clearly differs from decavanadate by enhancing, 12h after exposure, mitochondrial superoxide dismutase (SOD) activity (+115%) and not affecting catalase (CAT) activity whereas decavanadate increases SOD activity by 20% and decreases (-55%) mitochondrial CAT activity. At early times of exposure, 1 and 6h, the only effect observed upon decavanadate administration was the increase by 20% of SOD activity. In conclusion, decavanadate has a different response pattern of lipid peroxidation and oxidative stress markers, in spite of the same vanadium distribution in cardiac cells observed after decavanadate and metavanadate administration. It is suggested that once formed decameric vanadate species has a different reactivity than vanadate, thus, pointing out that the differential contribution of vanadium oligomers should be taken into account to rationalize in vivo vanadate toxicity.