UV-VIS Spectroscopy and Its Applications

Perkampus, H.‐H.

doi:10.1007/978-3-642-77477-5

Cited by 246 publications

(184 citation statements)

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“…The increase of the half-life of decameric vanadate upon increasing the protein concentration can be rationalized in terms of a complex formation between decameric vanadate and G-actin. Considering two equilibrium reactions, one between V10 and V1 and the other between V10 and the protein, and taking into account that the first one is much slower (time scale of hours) than the second (time scale of seconds or minutes at most) we can deduce that the velocity of decomposition of decameric vanadate species is inversely proportional to the increase of the protein concentration [37][38][39]. Almost a plateau of the half-life time was reached for Gactin concentration between 4 and 8 lM, and for 10 lM of decameric vanadate species, thus suggesting that the Gactin:V10 stoichiometry is approximately one or higher, contrarily to sarcoplasmic reticulum calcium ATPase with about five decameric vanadate molecules per calcium pump (Fig.…”

Section: Stabilization Of Decameric Vanadate By G-actin Under Polymermentioning

confidence: 99%

Decavanadate interactions with actin: Inhibition of G-actin polymerization and stabilization of decameric vanadate

Ramos

Manuel

Tiago

et al. 2006

Journal of Inorganic Biochemistry

101

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Decameric vanadate species (V10) inhibit the rate and the extent of G-actin polymerization with an IC50 of 68 ± 22 lM and 17 ± 2 lM, respectively, whilst they induce F-actin depolymerization at a lower extent. On contrary, no effect on actin polymerization and depolymerization was detected for 2 mM concentration of ''metavanadate'' solution that contains ortho and metavanadate species, as observed by combining kinetic with 51 V NMR spectroscopy studies. Although at 25°C, decameric vanadate (10 lM) is unstable in the assay medium, and decomposes following a first-order kinetic, in the presence of G-actin (up to 8 lM), the half-life increases 5-fold (from 5 to 27 h). However, the addition of ATP (0.2 mM) in the medium not only prevents the inhibition of G-actin polymerization by V10 but it also decreases the half-life of decomposition of decameric vanadate species from 27 to 10 h. Decameric vanadate is also stabilized by the sarcoplasmic reticulum vesicles, which raise the half-life time from 5 to 18 h whereas no effects were observed in the presence of phosphatidylcholine liposomes, myosin or G-actin alone. It is proposed that the ''decavanadate'' interaction with G-actin, favored by the G-actin polymerization, stabilizes decameric vanadate species and induces inhibition of G-actin polymerization. Decameric vanadate stabilization by cytoskeletal and transmembrane proteins can account, at least in part, for decavanadate toxicity reported in the evaluation of vanadium (V) effects in biological systems.

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Section: Stabilization Of Decameric Vanadate By G-actin Under Polymermentioning

confidence: 99%

Decavanadate interactions with actin: Inhibition of G-actin polymerization and stabilization of decameric vanadate

Ramos

Manuel

Tiago

et al. 2006

Journal of Inorganic Biochemistry

101

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“…Derivou-se os espectros de ordem zero, pois a espectrofotometria derivativa, que tem sido utilizada na análise de fármacos, 20,21 pode eliminar sinais de substâncias interferentes, como excipientes, aumentando a seletividade do método. Os espectros da 3D e 4D apresentaram muito ruído, mesmos após a suavização, o que resulta em desvio elevado nas medidas e, portanto, são inadequados para análise quantitativa.…”

Section: Resultsunclassified

“…O estudo da estabilidade da olanzapina, em ambos os solventes, a partir do espectro de ordem zero, mostrou que até o 30º dia as soluções, protegidas da luz, à temperatura ambiente ou sob refrigeração, permanecem com absorbâncias estatisticamente iguais, de acordo com análise de variância 20 (ANOVA, p= 0,05). No entanto, as amostras que permaneceram expostas à luz apresentaram diminuição progressiva do sinal a partir do 4º dia, em etanol, para a banda em 272,5 nm e do 10° dia, em isopropanol, na banda em 273,0 nm (Figura 4).…”

Section: Estabilidadeunclassified

Determinação de olanzapina em formulações farmacêuticas por espectrofotometria: desenvolvimento e validação

Rêgo¹,

Moura²,

Moita³

2010

Quím. Nova

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Recebido em 7/3/09; aceito em 7/7/09; publicado na web em 8/1/10 SPECTROPHOTOMETRIC OLANZAPINE DETERMINATION IN PHARMACEUTICAL FORMULATIONS: METHOD DEVELOPMENT AND VALIDATION. Spectrophotometric methods of zero order, first and second derived order had been developed for olanzapine determination in tablets using ethanol and isopropanol as solvent. The two solvents revealed to be adequate. For the three methods the calibration curve coefficient of correlation had been greater than 0. , in isopropanol. The inter-day precision was inferior to 1.1 and 1.9 mg L -1 for ethanol and isopropanol, respectively. The average recoveries varied from 98 to 101%, in ethanol and 99 to 103% in isopropanol.

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“…that have been reported for the spectrophotometric determination of Th(IV). [19][20][21] The separation of Th(IV) is done either by liquid-liquid extraction or by solid-phase extraction techniques.…”

Section: Introductionmentioning

confidence: 99%

Selective Extraction, Preconcentration and Transport Studies of Thorium(IV) Using Octa-Functionalized Calix[4]resorcinarene-Hydroxamic Acid

et al. 2005

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A new calix [4]resorcinarene bearing eight hydroxamic acid groups (C4RAHA) has been synthesized and characterized by FT-IR, 1 H-NMR and elemental analysis. Its analytical properties were investigated, and showed high affinity and selectivity toward thorium(IV) in the presence of large quantities of associated metal ions. Thorium(IV) was extracted from an ethyl acetate solution of C4RAHA at pH 4.5. The λmax and molar absorptivity (ε) for thorium(IV) were 341 nm and 7120 l mol -1 cm -1 . The complexation of thorium(IV) with C4RAHA has a 4:1 metal:ligand stoichiometry, which is relatively rare. The extracts were directly aspirated in the plasma for ICP-AES measurements for thorium(IV) in the presence of a diversified matrix. The system obeyed Beer's law over the range 0.1 -6.5 µg ml -1 of thorium(IV) with a Sandell sensitivity of 0.0325 µg cm -2 . The preconcentration factor and overall stability constant evaluated at 25˚C for thorium(IV) were 133 and 15.86, respectively. The complexation was characterized by a favorable enthalpy change. A liquid-membrane transport study of thorium(IV) was carried out from the source to the receiving phase under controlled conditions, and a mechanism of transport proposed. To check the validity of the proposed method, thorium(IV) was determined in monazite sand, rare earth sand and water samples.

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UV-VIS Spectroscopy and Its Applications

Cited by 246 publications

References 0 publications

Decavanadate interactions with actin: Inhibition of G-actin polymerization and stabilization of decameric vanadate

Decavanadate interactions with actin: Inhibition of G-actin polymerization and stabilization of decameric vanadate

Determinação de olanzapina em formulações farmacêuticas por espectrofotometria: desenvolvimento e validação

Selective Extraction, Preconcentration and Transport Studies of Thorium(IV) Using Octa-Functionalized Calix[4]resorcinarene-Hydroxamic Acid

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