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Query: UMLS:C0027960 (mole)
 21,279 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The separation and determination of the vanadium(V) ternary complex formed with 4-(2-pyridylazo)resorcinol (PAR) and hydrogen peroxide using ion-interaction reversed-phase high-performance liquid chromatography on a C18 column has been investigated. The optimal mobile phase was a methanol-water solution (32:68, v/v) containing 3 mM tetrabutylammonium bromide, 5 mM acetic acid and 5 mM citrate buffer at pH 7, with absorbance detection at 540 nm. The stoichiometry of the ternary complex of vanadium at pH 6 in 10 mM acetate buffer using the mole ratio and Job's method by HPLC indicated that the mole ratio of V(V):PAR:H2O2 was 1:1:1. The optimal conditions for precolumn formation of the ternary complex were 10 mM acetate, 7 mM H2O2, 0.3 mM PAR, and pH 6. The method gave relative standard deviations of retention time, peak area and peak height for the ternary complex of 0.187, 0.45 and 0.57%, respectively. The detection limit (at a signal-to-noise ratio of 3) for V(V) was 0.09 ng/ml in the digested sample using a 100-microl injection loop (or 0.09 microg/g in the solid fertiliser sample). The method was applied to the analysis of fertilisers (phosphate rocks and nitrogen, phosphorus and potassium fertiliser). The results for vanadium obtained by the HPLC method agreed well with those from magnetic sector inductively coupled plasma MS analysis.
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PMID:Determination of vanadium as 4-(2-pyridylazo)resorcinol-hydrogen peroxide ternary complexes by ion-interaction reversed-phase liquid chromatography. 1210 54

An L-amino acid oxidase (LAO), designated as TJ-LAO, was purified to homogeneity from the venom of Trimeresurus jerdonii by Sephadex G-100 and Q Sepharose HP chromatography. The molecular weight of this enzyme was 110 kD as estimated by analytical gel filtration and was 55 kD by SDS-polyacrylamide gel electrophoresis, suggesting that the enzyme is composed of two subunits. The enzyme has an absorption spectrum characteristic of flavoproteins, containing 2 moles of FMN per mole of enzyme. The N-terminal sequence of TJ-LAO shares high homology with other viperid snake venom LAOs. Homology with elapid venom LAO is lower. TJ-LAO inhibited the growth of Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, and Bacillus megaterium. The antibacterial effect associated with LAO activity was elminated with the addition of catalase. Platelets in platelet-rich plasma aggregated upon the addition of TJ-LAO. The enzyme-induced aggregation was inhibited by catalase, suggesting formation of H2O2 was essential for TJ-LAO to induce platelet aggregation. These results showed H2O2 formation is important for the biological effects of LAO.
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PMID:L-amino acid oxidase from Trimeresurus jerdonii snake venom: purification, characterization, platelet aggregation-inducing and antibacterial effects. 1250 78

Minerals containing peroxide are limited to studtite, (UO2)O2(H2O)4, and metastudtite, (UO2)O2(H2O)2. High-temperature oxide-melt solution calorimetry and solubility measurements for studtite (standard enthalpy of formation at 298 kelvin is -2344.7 +/- 4.0 kilojoules per mole from the elements) establishes that these phases are stable in peroxide-bearing environments, even at low H2O2 concentrations. Natural radioactivity in a uranium deposit, or the radioactivity of nuclear waste, can create sufficient H2O2 by alpha radiolysis of water for studtite formation. Studtite and metastudtite may be important alteration phases of nuclear waste in a geological repository and of spent fuel under any long-term storage, possibly at the expense of the commonly expected uranyl oxide hydrates and uranyl silicates.
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PMID:Stability of peroxide-containing uranyl minerals. 1461 33

3-mercapto-5-(3,4-dihydroxyphenylazo-1')-1,2,4-triazole (METRIAP), 3-mercapto-5-(2,4-dihydroxy-3-carboxyphenylazo-1)-1,2,4-triazole (METRIAREZ-gamma) and 2-mercapto-5-(2,4-dihydroxy-5-carboxyphenylazol-)-1,3,4-thiadiazole (METIDAREZ-beta), reagents synthesized in the Department of Medicinal Chemistry of Medical University in Lublin, have been used to determine Fe(II) and Zn(II) in Materna, Centrum, H-Pantoten pharmaceutical multivitamin preparations, containing other trace elements. Zn (II) with METRIAREZ-gamma at pH=7.35, and Fe(II) with METRIAP and METIDAREZ-beta at pH=10.30 or 7.40 constitute soluble in H2O colourful chelate compound at a mole ratio of 1:2 and 1:3, respectively. Volume stability constant of Fe(II) and Zn(II) complexes is equal to log K(METRIAP-Fe(II)) = 16.46; log K(METRIAREZ-beta-Fe(II)) = 14.253; log K(METRIAREZ-gammaZn(II)) = 11.47. Fe(III) and Zn(II) solutions were obtained by wet mineralisation of Materna, Centrum and H-Pantoten preparations with concentrated H2SO4 and 30% H2O2 added. Spectrophotometric determination was carried out in an aqueous-methanolic solution environment. Statistically evaluated results were compared with the results of the AAS (atomic absorption spectrophotometry) determination method. Advantages of the Fe(II) and Zn(II) determination method are its precision RSD = 0.23%-2.09% and repeatability as well as the possibility of Fe(II) determination without the necessity of masking or separating other trace elements.
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PMID:Spectrophotometric determination of Fe(II) and Zn(II) in the pharmaceutical multivitamin preparations with microelements. 1548 Dec 41

This study evaluated the dissolution behavior of basic oxygen furnace slag (BOF slag) and the performance of H2O2 with BOF slag denoted as H2O2/BOF slag process to degrade polyethylene glycol (PEG) in the aqueous solution. The concentration of total organic carbon (TOC) was chosen as a mineralization index of the degradation of PEG by the H2O2/BOF slag process. A first-order kinetic model with respect to TOC was adopted to represent the mineralization of PEG by H2O2/BOF slag process. The experimental results in this study suggested that dosages with 3.98 x 10(-4) mole min(-1) l(-1) H2O2 and 15 g l(-1) BOF slag loading in the solution at pH 2 provided the optimal operation conditions for the mineralization of PEG yielding a 75.5% treatment efficiency at 100 min reaction time. The H2O2/Fe2+ ratio was then determined to be 13.5:1.
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PMID:Mineralization of polyethylene glycol in aqueous solution by hydrogen peroxide with basic oxygen furnace slag. 1569 Nov 96

We present a direct ab initio dynamics study on the hydrogen abstraction reaction CH2O + HO2 --> CHO + H2O2, which is predicted to have four possible reaction channels caused by different attacking orientations of HO2 radical to CH2O. The structures and frequencies at the stationary points and the points along the minimum energy paths (MEPs) of the four reaction channels are calculated at the B3LYP/cc-pVTZ level of theory. Energetic information of stationary points and the points along the MEPs is further refined by means of some single-point multilevel energy calculations (HL). The rate constants of these channels are calculated using the improved canonical variational transition-state theory with the small-curvature tunneling correction (ICVT/SCT) method. The calculated results show that, in the whole temperature range, the more favorable reaction channels are Channels 1 and 3. The total ICVT/SCT rate constants of the four channels at the HL//B3LYP/cc-pVTZ level of theory are in good agreement with the available experiment data over the measured temperature ranges, and the corresponding three-parameter expression is k(ICVT/SCT) = 3.13 x 10(-20) T(2.70) exp(-11.52/RT) cm3 mole(-1) s(-1) in the temperature range of 250-3000 K. Additionally, the flexibility of the dihedral angle of H2O2 is also discussed to explain the different experimental values.
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PMID:Direct dynamics study on the hydrogen abstraction reaction CH2O + HO2 --> CHO + H2O2. 1636 58

Apurinic/apyrimidinic endonuclease-1/redox factor-1 (APE/Ref-1) is a multifunctional protein involved in DNA base excision repair and redox regulation of many transcription factors. In different melanoma cell lines, we found that both nucleus and cytoplasm exhibited higher levels of Ref-1 compared with normal melanocytes. Similar increases of Ref-1 expression, detected by immunohistofluorescence, were also evident in nevi and malignant melanoma biopsies compared with normal skin, which were predominantly localized in the nucleus. Using recombinant adenovirus Adref-1, encoding full-length Ref-1, we transiently overexpressed APE/Ref-1 in human melanocytes, which protected these cells from UVB-induced apoptosis and increased foci formation in culture. Ref-1 overexpression also protected melanoma cells from cisplatin- or H2O2-induced apoptosis, whereas increased apoptosis was observed with Ref-1 antisense construct infection. These observations suggested that intracellular Ref-1 levels played an important role in sensitization of melanoma cells to apoptosis. Electrophoretic mobility shift assay results showed that in both cultured primary and metastatic melanomas DNA-binding activities of activator protein-1 and nuclear factor-kappaB were significantly diminished or shifted when anti-APE/Ref-1 antibody was added to deplete APE/Ref-1 from the binding complexes. Induced nuclear factor-kappaB transcriptional activities were also evident after Ref-1 overexpression. Furthermore, using three-dimensional molecular structure modeling and virtual screening, we found that resveratrol, a natural compound found in fruits and vegetables, docks into a druggable pocket of Ref-1 protein. In vitro studies revealed that resveratrol inhibited, in a dose-dependent manner, Ref-1-activated activator protein-1 DNA-binding activities as well as Ref-1 endonuclease activities and rendered melanoma cells more sensitive to dacarbazine treatment.
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PMID:Alterations in the expression of the apurinic/apyrimidinic endonuclease-1/redox factor-1 (APE/Ref-1) in human melanoma and identification of the therapeutic potential of resveratrol as an APE/Ref-1 inhibitor. 1637 7

A synthetic strategy to control the density of Mn12 clusters anchored on silicon(100) was investigated. Diluted monolayers suitable for Mn12 anchoring were prepared by Si-grafting mixtures of the methyl 10-undecylenoate precursor ligand with 1-decene spectator spacers. Different ratios of these mixtures were tested. The grafted surfaces were hydrolyzed to reveal the carboxylic groups available for the subsequent exchange with the [Mn12O12(OAc)16(H2O)4]4 H2O2 AcOH cluster. Modified surfaces were analyzed by attenuated total reflection (ATR)-FTIR spectroscopy, X-ray photoemission spectroscopy (XPS), and AFM imaging. Results of XPS and ATR-FTIR spectroscopy show that the surface mole ratio between grafted ester and decene is higher than in the source solution. The surface density of the Mn12 cluster is, in turn, strictly proportional to the ester mole fraction. Well-resolved and isolated clusters were observed by AFM, using a diluted ester/decene 1:1 solution.
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PMID:Density control of dodecamanganese clusters anchored on silicon(100). 1649 89

To search for an insect homologue of antioxidant protein 1 (ATX1), a mole cricket, Gryllotalpa orientalis, cDNA library was screened and a cDNA clone, which encodes a 73 amino acid polypeptide with a predicted molecular mass of 8.0 kDa and pI of 5.68, was isolated. The G. orientalis ATX1 (GoATX1) cDNA features both a MTCXXC copper-binding site in the N-terminus and a KTGK lysine-rich region in the C-terminus. The deduced amino acid sequence of the GoATX1 cDNA showed 63% identity to Drosophila melanogaster ATX1 and 55% to Ixodes pacificus ATX1. Northern blot analysis revealed the presence of GoATX1 transcripts in midgut, fat body, and epidermis. When H2O2 was injected into the body cavity of G. orientalis adult, GoATX1 mRNA expression was up-regulated in the fat body tissue. Fat body expression level of GoATX1 mRNA in the fat body was increased following exposure to low (4 degrees C) and high (37 degrees C) temperatures, suggesting that GoATX1 plays a protective role against oxidative stress caused by temperature shock. This is the first report about a functional role of insect ATX1 in antioxidant defense.
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PMID:Molecular cloning and characterization of ATX1 cDNA from the mole cricket, Gryllotalpa orientalis. 1655 68

Ozonation and ozone process combined with hydrogen peroxide have been identified as new technologies for direct or indirect reuse of wastewater. This study aims to establish appropriate conditions to control the formation of BrO3 and brominated organic compounds during O3/H2O2 treatment of secondary effluents of sewage. When the H2O2/O3 mole ratio of injection was above 0.5 and the DO3 concentration was below 0.1 mg/L, BrO3 was controlled as well as treatment purpose was completed. TOBr formation in O3/H2O2 treatment was also completely controlled.
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PMID:Control of bromate ion and brominated organic compounds formation during ozone/hydrogen peroxide treatment of secondary effluent. 1674 54


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