Evaluation of Effects of Bivalent Cations on the Formation of Purine-rich Triple-Helix DNA by ESI-FT-MS

The GGA triplet repeats are widely dispersed throughout eukaryotic genomes. (GGA)n or (GGT)n oligonucleotides can interact with double-stranded DNA containing (GGA:CCT)n to form triple-stranded DNA. The effects of 8 divalent metal ions (3 alkaline-earth metals and 5 transition metals) on formation of these purine-rich triple-helix DNA were investigated by electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI-FT-MS). In the absence of metal ions, no triplex but single-strand, duplex, and purine homodimer ions were observed in mass spectra. The triple-helix DNA complexes were observed only in the presence of certain divalent ions. The effects of different divalent cations on the formation of purine-rich triplexes were compared. Transition-metal ions, especially Co2+ and Ni2+, significantly boost the formation of triple-helix DNA, whereas alkaline-earth metal ions have no positive effects on triplex formation. In addition, Ba2+ is notably beneficial to the formation of homodimer instead of triplex.

复方板蓝根颗粒水提部位的ESI-MS指纹图谱研究

Sialic acid and lysine as an internal standard substance,the ESI-MS fingerprinting of extracts of Compound Indigowoad Root Granule which from different origin was studied.The fingerprinting was obtained with better precision and reproducibility.This work can provide a reference for the quality control of Compound Indigowoad Root Granule.

ESI-MS法研究白芍炮制前后化学成分的变化

ESI-MS analytical method was employed to study extracts of unprocessed and processed Radix Paeoniae alba.The results of the experiments prove that different processed methods is making a certain different influence on the contents of chemiacl components in Radix Paeoniae alba.This method is simple and accurate.It can be used for analyse of Traditional Chinese Medicine(TCM).

乌头碱在家兔肠道内代谢产物的LC/ESI-MSn研究

采用LC/ESI-MSn的方法对家兔肠道内的乌头碱代谢产物进行研究,经与空白组比较发现,给药后家兔小肠内容物中新增加6个化合物峰(M1～M6),盲肠内容物中新增加5个化合物峰(M2～M6),粪便中新增加2个化合物峰(M3、M4). 分别测定各化合物的准分子离子及各级串联碎片离子,并与标准品的质谱断裂规律进行比较,同时参考文献,推断肠道内化合物M1为16-O-去甲基-8-O-去乙酰基乌头碱,M2为8-O-去乙酰基乌头碱,M3为16-O-去甲基乌头碱,M4为乌头碱(AC),M5为去氧乌头碱,为印乌头碱。

Bimolecular quadruplexes and their transitions to higher-order molecular structures detected by ESI-FTICR-MS

Four individual quadruplexes, which are self-assembled in ammonium acetate solution from telomeric sequences of closely related DNA strands - d(G(4)T(4)G(4)), d(G(3)T(4)G(4)), d(G(3)T(4)G(3)), and d(G(4)T(4)G(3)) - have been detected in the gas phase using electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI-FTICR-MS). The bimolecular quadruplexes associate with the same number of NH4+ in the gas phase as NMR shows that they do in solution. The quadruplex structures formed in solution are maintained in the gas phase. Furthermore, the mass spectra show that the bimolecular quadruplexes generated by the strands d(G(3)T(4)G(3)) and d(G(4)T(4)G(3)) are unstable, being converted into trimolecular and tetramolecular structures with increasing concentrations of NH4+ in the solution. Circular dichroism (CD) spectra reveal structural changes during the process of strand stoichiometric transitions, in which the relative orientation of strands in the quadruplexes changes from an antiparallel to a parallel arrangement. Such changes were observed for the strand d(G(4)T(4)G(3)), but not for the strand d(G(3)T(4)G(3)). The present work provides a significant insight into the formation of various DNA quadruplexes, especially the higher-order species.

Studies on the content variation of chemical constituents during the combination of ginseng with veratrum nigrum by ESI-MS and HPLC-ESI-MS

To study the content variation of ginsenosides and alkaloids during combination of ginseng with veratrum nigrum, the ginsenosides and alkaloids in the decoction of ginseng with veratrum nigrum were analyzed and compared by high performance liquid chromatography-electrospray ionization-mass spectrometry (HPLC-ESI-MS) and electrospray ionization-mass spectrometry (ESI-MS). In the compatible decoction, eight ginsenosides and eight alkaloids. were detected, and the contents of six ginsenosides were found to be reduced, on the contrary, the contents of six alkaloids were increased. During combination of ginseng with veratrum nigrum, the contents of ginsenosides were reduced and those of the toxic alkaloids were increased. From the chemical point of view, the traditional theory is right that ginseng and veratrum nigrum are incompatible with each other.

Characterization of linear epitope of the beta(2)-microglobulin via combination of MALDI-TOF-MS with immunoaffinity

Matrix-assisted laser desorption ionization time-of-flight mass spectrometry(MALDI-TOF-MS), in combination with immunoaffinity provided a powerful tool for determining epitope (antigenic determinant) in protein. The linear epitope of the beta(2)-microglobulin was characterized in the paper. The method as follows: at first beta(2)-microglobulin was digested by a proteolytic enzyme to produce an appropriate set of peptide fragments, then peptide fragments containing the linear epitope were selected and separated from the pool of peptide fragments by immunoprecipitation with the monoclonal antibody. The agarose beads were collected carefully after the reaction. Unbound peptides would be washed away, while the peptides containing the epitope would remain bound to the immobilized antibody after. the beads were washed several times with appropriate buffer. At last the masses of the bound peptides were identified directly by MALDI-TOF MS. Using Endoproteinase Glu-C Endoproteinase Lys-C and Trypsin in the experiment, the linear epitope of beta(2)-microglobulin was located within peptide fragment 59-69, that is, DWSFYLLYYTE.

MALDI-TOF-MS法对重组人内皮抑素蛋白分子质量测定

肿瘤的生长依赖于血管的生成,新生血管不仅为肿瘤生长提供必需的营养物质,而且为肿瘤细胞扩散提供了重要的途径[1].1997年哈佛大学的O'Reilly等[2]发现了一种内源性新血管生成抑制因子内皮抑素(Endostatin),显示出特异抑制激活的血管内皮细胞增殖和肿瘤新血管生成的生物学活性,其抗肿瘤作用具有高效、低毒、无耐药性的优点.

Comparison of biochemical effects induced by Changle between male and female rats using NMR and ICP-MS techniques

Metabolic profiles caused by rare earth complex were investigated using NMR and ICP-MS techniques. Male and female Wistar rats were treated orally with Changle (A kind of rare earth complex applied in agriculture to raise the production of crops) at dose of 2, 5 and 20 mg (.) kg(-1) body weight/day respectively for 90 d. Urine and serum samples are collected on 90 d. The relative concentrations of important endogenous metabolites in urine and serum are determined from H-1 NMR spectra and the contents of the four rare earth elements ( La, Ce, Pr and Nd) constituting Changle in the serum samples are measured by ICP-MS technique. Changle-induced renal and liver damage in rats is found based on the increase in the amounts of the amino acids, trimethylamine N-oxide, N, N-dimethyglycine, dimethylamine, succinate, aketoglutarate and ethanol as well as rare earth concentrations. The similarities and differentiations are found in the alteration patterns of metabolites and rare earth concentrations in serum.

High-sensitivity molecular mass determination of lysozyme prior to MALDI-MS

Sodium dodecyl sulfate(SDS) is a powerful solubilizing detergent which is often used during the separation of highly complex protein mixtures by one- or two-dimensional (2D) gel electrophoresis. Matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) is a widely used technique for mass spectrometric analysis of some protein molecules compared to other techniques. But the presence of SDS or some salts usually leads to signal deterioration when using MALDI-MS. A method for using nitrocellulose membrane as the solid-phase carrier combined with n-octyl-beta-D-glucopyranoside in the matrix highly enhances the sensitivity of the molecular mass determination of lysozyme. This technique has the advantage that the signal-to-noise of the molecular weight profile is improved compared with the mass spectrum and the profile is relatively easy to interpret.

Determination of rare and rare earth elements in soils and sediments by ICP-MS using Ti(OH)(4)-Fe(OH)(3) co-precipitation preconcentration

A method was developed for the determination of trace and ultratrace amounts of REE. Cd. In. Tl. Th. Nb, Ta. Zr and Hf in soils and sediments. With NaOH-Na2O2 as the flux. Ti(OH)(4)-Fe(OH)(3) co-precipitation as the preconcentration technique and inductively coupled plasma mass spectrometry (ICP-MS) for measurement, the whole procedure was concise and suitable for batch analysis of multi-element solutions. An investigation was carried out of the Ti(OH)(4)-Fe(OH)(3) co-precipitation system, and the results obtained showed that the natural situation of Ti tightly coexisting with Nb. Ta, Zr and Hf in geological samples plays a very important role in the complete co-precipitation of the four elements. The accuracy of this procedure was established using six Chinese soil and sediment certified reference materials (GSS and GSD). and the relative errors between the found and certified values were mostly below 10%.

提高MALDI-MS测量溶菌酶分子量灵敏度的研究

近 1 0年来 ,基质辅助激光解吸质谱 (MALDI- MS)作为一种新兴的“软电离”质谱技术 [1,2 ] ,已很快地应用于生物大分子特别是蛋白质研究领域 [3 ] .MALDI- MS可在 1 0 - 12 mol甚至 1 0 - 15mol的水平上 ,准确地测定分子量高达几万到几十万的生物大分子 ;还可通过改变基质、溶液条件和样品的制备方法等实现大分子蛋白质非共价复合物的质谱检测 [4 ] .MALDI- MS能够得到如此广泛的应用 ,在很大程度上要归功于基质的辅助效应 .基质的作用主要可以概括如下 [5～ 7] :(1 )削弱样品分子间的相互作用 ;(2 )与样品分子结合并使之快速结晶 ;(3 )帮助样品分子从激光脉冲中吸收能量 ,使其产生瞬间相变 ,当能量达到本体解吸临界值时便可得到离子信号 .Garozzo等 [8]曾报道了以羟基苯乙酮为基质可提高测量多种谷蛋白粘胶质分子量的灵敏度 .其中以 2 ,4,6 -三羟基苯乙酮 (2 ,4,6 - THAP)与 TFA混合作基质和 2 ,6 -二羟基苯乙酮 (2 ,6 - DHAP)与 H2 O,ACN混合作基质灵敏度最高 .表明这类基质在通过气相离子 ...

人参四逆汤成分的研究

利用ESI/MS~n、LC/MS、MALDI-TOF/MS等技术,从人参四逆汤水煎液中分析和鉴定了10种二萜生物碱:苯甲酰中乌头碱benzoylmesaconitine、苯甲酰乌头碱henzoylaconitine、苯甲酰次乌头碱benzoylhypacoitine、尼奥灵neoline、附子灵fuziline、14-乙酰基塔拉地萨敏14-acetyl-talatisamine、苯甲酰次乌头碱亚油酸酯14-benzoylhypaconine-8-linoleate、苯甲酰去氧乌头碱亚油酸酯14-benzoydeoxyaconine-8-oleate、苯甲酰次乌头碱棕榈酸酯14-benzoylhypaconine-8-palmitate、塔拉地萨敏talatisamine和人参皂甙R_(a1)、R_(a2)、R_(b1)、R_(b2)、R_(b3)、R_c、R_d、R_e、R_(g1)、R_(g2)、R_(g3)、R_f等12种人参皂甙。脂肪酸酯型生物碱和苯甲酰类生物碱的提取组分有抗失血性休克作用和弱的正性肌力作用。人参皂甙的提取组分具有明显的负性肌力作用。

Rapid identification of saponins in plant extracts by electrospray ionization multi-stage tandem mass spectrometry and liquid chromatography/tandem mass spectrometry

Electrospray ionization multi-stage tandem mass spectrometry (ESI-MSn) and liquid chromatography coupled with on-line mass spectrometry (LC/MS/MS) were applied to characterize saponins in crude extracts from Panax ginseng. The MSn data of the [M - H](-) ions of saponins can provide structural information on the sugar sequences of the saccharide chains and on the sapogins of saponins. By ESI-MSn, non-isomeric saponins and isomeric saponins with different aglycones can be determined rapidly in plant extracts. LC/MS/MS is a good complementary analytical tool for determination of isomeric saponins. These approaches constitute powerful analytical tools far rapid screening and structural assignment of saponins in plant extracts. Copyright (C) 2000 John Wiley & Sons, Ltd.