排序方式: 共有41条查询结果,搜索用时 31 毫秒
11.
Menadione sodium bisulfite (MSB) is a stable water-soluble derivative of Vitamin K3, which is found to be able to enhance the ECL of luminol at potential of 0.88 V in phosphate buffer solution. The conditions for the enhanced ECL, such as the selection of the type of buffer solution, applied potential mode, scanning rate, the effect of pH and concentration of luminol have been investigated in detail in this paper. Under the optimum conditions, the enhanced ECL intensity is linear with the concentration of MSB over a wide range, the detection limit for MSB is 3.0 × 10−7 mol/L. The proposed method has been applied to determine the MSB in the commercial injection samples. A possible mechanism for the enhanced ECL of luminol by MSB has also been proposed. 相似文献
12.
Sandeep Mohanty Amrendra Kumar Roy Vinay K.P. Kumar Sandeep G. Reddy Arun Chandra Karmakar 《Tetrahedron letters》2014
We describe a simple and efficient one-pot method for condensing bisulfite adducts of aromatic aldehydes directly with 2,4-thiazolidinedione catalyzed by acetic anhydride. The two main highlights of this study are the one-pot condensation of bisulfite adducts with 2,4-thiazolidinedione in non-aqueous media and the use of Design of Experiment to understand and optimize the reaction conditions. This methodology was then generalized using other active methylene compounds, such as malononitrile. 相似文献
13.
Marie G. Kissane Scott A. Frank Gregory A. RenerChristopher P. Ley Charles A. AltPaul A. Stroud Radhe K. VaidSathish K. Boini Laura A. McKeeJeffrey T. Vicenzi Gregory A. Stephenson 《Tetrahedron letters》2013
The identification and development of an aldehyde–bisulfite adduct as an isolable starting material in the synthesis of the CETP inhibitor Evacetrapib are described. The physical properties of the sodium and potassium analogs are compared, and the extension of the scope of this study to include an investigation into the solid state properties of a range of sodium and potassium bisulfite adducts of commonly encountered aldehydes is discussed. 相似文献
14.
Qing Shi Ling-Yi Shen Hong Xu Zhi-Yong Wang Xian-Jiong Yang Ya-Li Huang Carl Redshaw Qi-Long Zhang 《Molecules (Basel, Switzerland)》2021,26(11)
A novel 1-hydroxy-2,4-diformylnaphthalene-based fluorescent probe L was synthesized by a Knoevenagel reaction and exhibited excellent sensitivity and selectivity towards sulfite ions (SO32−) and bisulfite ions (HSO3−). The detection limits of the probe L were 0.24 μM using UV-Vis spectroscopy and 9.93 nM using fluorescence spectroscopy, respectively. Furthermore, the fluorescent probe L could be utilized for detection in real water samples with satisfactory recoveries in the range 99.20%~104.30% in lake water and 100.00%~104.80% in tap water by UV-Vis absorption spectrometry, and in the range 100.50%~108.60% in lake water and 102.70%~103.80% in tap water by fluorescence spectrophotometry. 相似文献
15.
Quantitative analysis of DNA methylation in the promoter region of the methylguanine‐O6‐DNA‐methyltransferase gene by COBRA and subsequent native capillary gel electrophoresis
下载免费PDF全文
![点击此处可从《Electrophoresis》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Simon Goedecke Jörg Mühlisch Georg Hempel Michael C. Frühwald Bernhard Wünsch 《Electrophoresis》2015,36(23):2939-2950
Along with histone modifications, RNA interference and delayed replication timing, DNA methylation belongs to the key processes in epigenetic regulation of gene expression. Therefore, reliable information about the methylation level of particular DNA fragments is of major interest. Herein the methylation level at two positions of the promoter region of the gene methylguanine‐O6‐DNA‐Methyltransferase (MGMT) was investigated. Previously, it was demonstrated that the epigenetic status of this DNA region correlates with response to alkylating anticancer agents. An automated CGE method with LIF detection was established to separate the six DNA fragments resulting from combined bisulfite restriction analysis of the methylated and non‐methylated MGMT promoter. In COBRA, the DNA was treated with bisulfite converting cytosine into uracil. During PCR uracil pairs with adenine, which changes the original recognition site of the restriction enzyme Taql. Artificial probes generated by mixing appropriate amounts of DNA after bisulfite treatment and PCR amplification were used for validation of the method. The methylation levels of these samples could be determined with high accuracy and precision. DNA samples prepared by mixing the corresponding clones first and then performing PCR amplification led to non‐linear correlation between the corrected peak areas and the methylation levels. This effect is explained by slightly different PCR amplification of DNA with different sequences present in the mixture. The superiority of CGE over PAGE was clearly demonstrated. Finally, the established method was used to analyze the methylation levels of human brain tumor tissue samples. 相似文献
16.
Songjun Guo Sheng Wen Guoying Sheng Jiamo Fu 《Isotopes in environmental and health studies》2013,49(4):473-482
δ13C values of gaseous acetaldehyde were measured by gas chromatograph–combustion–isotope ratio mass spectrometer (GC–C–IRMS) via sodium bisulfite (NaHSO3) adsorption and cysteamine derivatisation. Gaseous acetaldehyde was collected via NaHSO3-coated Sep-Pak® silica gel cartridge, then derivatised with cysteamine, and then the δ13C value of the acetaldehyde–cysteamine derivative was measured by GC–C–IRMS. Using two acetaldehydes with different δ13C values, derivatisation experiments were carried out to cover concentrations between 0.009×10?3 and 1.96×10?3 mg·l?1) of atmospheric acetaldehyde, and then δ13C fractionation was evaluated in the derivatisation of acetaldehyde based on stoichiometric mass balance after measuring the δ13C values of acetaldehyde, cysteamine and the acetaldehyde–cysteamine derivative. δ13C measurements in the derivertisation process showed good reproducibility (<0.5 ‰) for gaseous acetaldehyde. The differences between predicted and measured δ13C values were 0.04–0.31 ‰ for acetaldehyde–cysteamine derivative, indicating that the derivatisation introduces no isotope fractionation for gaseous acetaldehyde, and obtained δ13C values of acetaldehyde in ambient air at the two sites were distinct (?34.00 ‰ at an urban site versus?31.00 ‰ at a forest site), implying potential application of the method to study atmospheric acetaldehyde. 相似文献
17.
Freneil B. Jariwala Ryan E. Wood Upul Nishshanka Athula B. Attygalle 《Journal of mass spectrometry : JMS》2012,47(4):529-538
In the negative‐ion collision‐induced dissociation mass spectra of most organic sulfonates, the base peak is observed at m/z 80 for the sulfur trioxide radical anion (SO3–·). In contrast, the product‐ion spectra of a few sulfonates, such as cysteic acid, aminomethanesulfonate, and 2‐phenylethanesulfonate, show the base peak at m/z 81 for the bisulfite anion (HSO3–). An investigation with an extensive variety of sulfonates revealed that the presence of a hydrogen atom at the β‐position relative to the sulfur atom is a prerequisite for the formation of the bisulfite anion. The formation of HSO3– is highly favored when the atom at the β‐position is nitrogen, or the leaving neutral species is a highly conjugated molecule such as styrene or acrylic acid. Deuterium‐exchange experiments with aminomethanesulfonate demonstrated that the hydrogen for HSO3– formation is transferred from the β‐position. The presence of a peak at m/z 80 in the spectrum of 2‐sulfoacetic acid, in contrast to a peak at m/z 81 in that of 3‐sulfopropanoic acid, corroborated the proposed hydrogen transfer mechanism. For diacidic compounds, such as 4‐sulfobutanoic acid and cysteic acid, the m/z 81 ion can be formed by an alternative mechanism, in which the negative charge of the carboxylate moiety attacks the α‐carbon relative to the sulfur atom. Experiments conducted with deuterium‐exchanged and deuterium‐labeled analogs of sulfocarboxylic acids demonstrated that the formation of the bisulfite anion resulted either from a hydrogen transfer from the β‐carbon, or from a direct attack by the carboxylate moiety on the α‐carbon. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
18.
《Analytical letters》2012,45(1):40-52
AbstractA two-photon fluorescent probe has been adopted for bisulfite based on an intramolecular charge transfer (ICT) mechanism. The fluorescence intensity of the probe decreased by 837 fold following treatment with HSO3? and the detection limit was 42?nM. This probe showed excellent properties such as high photostability, good two-photon properties, and large Stokes shifts. More importantly, this approach offers a rapid, highly selective, and sensitive method to determine HSO3? in buffer solutions and real samples. Furthermore, the probe was successfully used for two-photon fluorescence visualization of trace SO2 derivatives in biological systems. 相似文献
19.
An alternative strategy for the label‐free electrochemical detection of DNA hypermethylation using a microelectrode array as an oligodinucleotide (ODN) detector is presented. It relies on the oligonucleotide dependent electrostatic affinity interaction firstly with unmethylated ODN and then follow‐up with methylated DNA. The methylated cytosine status is quantified by monitoring the relative change in the exchange current at the ODN‐detector before and after the bisulfite treated DNA samples. This novel aproach displays unique advantages such as small working volumes of the analytes, low damage to DNA samples, easy integration of oligonucleides on the detector and signal evaluation. 相似文献
20.
Hayatsu H 《Proceedings of the Japan Academy. Series B, Physical and biological sciences》2008,84(8):321-330
Methylation at position 5 of cytosine in DNA is being intensively studied in many areas of biological sciences, as the methylation is intimately associated with the control of gene functions. The principal analytical method for determining the sites of 5-methylcytosine in genome at the sequence level involves bisulfite modification of DNA. The utility of this chemical treatment is based on the property of bisulfite to selectively deaminate cytosine residues. The bisulfite-mediated cytosine deamination was discovered in 1970 by us in the University of Tokyo. At the same time, Shapiro and his coworkers in New York University found the same reaction independently. We also reported that 5-methylcytosine was deaminated by bisulfite only very slowly. These findings were later utilized by a group of Australian scientists to devise a means to analyze 5-methylcytosine in DNA; thus, a method called 'bisulfite genomic sequencing' was invented by these researchers in 1992. This review describes the author's reflection of the discovery of bisulfite reactions with pyrimidine bases. The author's recent work that has resulted in an improvement of the procedure of analysis by use of a newly devised high concentration bisulfite solution is also described. 相似文献