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Analysis of in vivo-derived amyloid-β polypeptides by on-line two-dimensional chromatography-mass spectrometry

ANALYTICAL BIOCHEMISTRY 2001年第1期298卷 32-39页

作者： Clarke, NJ Crow, FW Younkin, S Naylor, S Mayo Clin & Mayo Fdn Dept Chem & Mol Biol Biomed Mass Spectrometry & Funct Proteom Facil Rochester MN 55905 USA Mayo Clin & Mayo Fdn Dept Pharmacol Rochester MN 55905 USA Mayo Clin & Mayo Fdn Clin Pharmacol Unit Rochester MN 55905 USA Mayo Clin Dept Pharmacol Jacksonville FL 32224 USA

The presence of senile plaques composed of amyloid-beta (A beta) polypeptides within brain tissue is normally used as a definitive postmortem diagnosis for Alzheimer's Disease (AD). Therefore, these polypeptides have been investigated as potential biomarkers of the disease state. However, at present, there is a lack of a robust assay for the detection of such polypeptides derived from in vivo sources. Such an assay is essential for analysis of biological samples from model AD systems. To overcome this problem we have developed a new single-step assay utilizing two dimensional-chromatography in conjunction with mass spectrometry. The method consists of on-line size-exclusion chromatography (SEC) to provide initial separation of analytes from the sample (based on their molecular weight) coupled with sample preconcentration prior to analysis by microbore high-performance liquid chromatography-mass spectrometry (HPLC-MS). This provides an extremely versatile and powerful assay which can separate specific analytes from cell lysate in a single step without further sample handling. The use of mass spectrometry as the detection system yields much more structural information than can be obtained from traditional ELISA and sandwich ELISA antibody assays. Furthermore, the on-line sample cleanup protocol minimizes sample handling and facilitates assay automation. Utilizing this new assay we have been able to detect A beta 1-40 and A beta 1-42 at cellular concentration levels directly from cell lysates. Moreover, we have detected multiple peptide responses within the same analysis, some of which have been tentatively identified as other ragged C-termini A beta polypeptides derived from A beta 1-42, based on their molecular weight, as well as oxidized A beta polypeptides. (C) 2001 Academic Press.

关键词：淀粉样β蛋白/分析淀粉样β蛋白/化学合成脑/细胞学脑化学细胞培养的/化学细胞培养的/细胞学色谱法凝胶/仪器和设备色谱法高压液相/仪器和设备培养基条件性/化学质谱分析法/仪器和设备质谱分析法/方法联机系统/仪器和设备肽碎片/分析肽碎片/化学合成动物豚鼠

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Characterization of an improved electrodynamic ion funnel interface for electrospray ionization mass spectrometry

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ANALYTICAL CHEMISTRY 1999年第15期71卷 2957-2964页

作者： Shaffer, SA Tolmachev, A Prior, DC Anderson, GA Udseth, HR Smith, RD Pacific NW Lab Environm Mol Sci Lab Richland WA 99352 USA

An improved electrodynamic ion funnel for ion focusing at high pressure (>1 Torr) has been developed for a triple quadrupole mass spectrometer and its performance compared with that of an earlier prototype previously reported. The ion funnel consists of a series of ring electrodes of progressively smaller interval diameters to which rf and de electric potentials are co-applied, The new design utilizes ring electrodes possessing larger internal diameters that taper down to a relatively larger exit aperture. in the 1-10 Torr pressure range, the new design provides significant improvement in low m/z ion transmission. Additionally, the overall ion transmission range is improved by linked scanning of the ion funnel's rf voltage concomitantly with the scanning of the quadrupole mass analyzer. Transmission of a noncovalent complex through the interface demonstrated that excessive ion heating was not problematic. Computer simulations of ion transport support the ion funnel design and help explain the relative performance of both designs. Both ion simulations and experimental results are in accord and indicate close to 100% ion transmission efficiency for electrosprayed biopolymer ions through the interface and into the mass analyzer.

关键词：计算机模拟细胞色素c组/化学电磁场脑啡肽亮氨酸/化学短杆菌肽/化学马离子转运离子选择电极离子质谱分析法/仪器和设备质谱分析法/方法模型化学肌红蛋白/化学肽类/化学敏感性与特异性动物

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An integrated microfabricated device for dual microdialysis and on-line ESI ion trap mass spectrometry for analysis of complex biological samples

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ANALYTICAL CHEMISTRY 1999年第8期71卷 1485-1490页

作者： Xiang, F Lin, YH Wen, J Matson, DW Smith, RD Pacific NW Natl Lab Environm Mol Sci Lab Richland WA 99352 USA

A microfabricated dual-microdialysis device in a single integrated microfabridated platform was constructed using laser micromachining techniques for the rapid fractionation and cleanup of complex biological samples. On-line dual microdialysis and ESI-MS of biological samples was demonstrated using an ion trap mass spectrometer. The mass spectra obtained demonstrated the efficiency of dual microdialysis for removing both high-molecular-weight and low-molecular-weight species that interfere with effective ESI-MS analysis of target biopolymers. Signal-to-noise ratios were also greatly improved compared to direct sample infusion. In addition to its compactness, negligible dead volume, and robustness, the device can be used at a now rate of only 200 nL/min, an order of magnitude lower than that obtained previously. This reduced sample consumption and improved sensitivity with ESI-MS. The results suggest the potential for integration of such microfabricated devices with other sample manipulations for the rapid ESI-MS analysis of complex biological samples.

关键词：大肠杆菌/化学质谱分析法/仪器和设备微透析/仪器和设备分子量联机系统

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Integration of microfabricated devices to capillary electrophoresis-electrospray mass spectrometry using a low dead volume connection: Application to rapid analyses of proteolytic digests

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ANALYTICAL CHEMISTRY 1999年第15期71卷 3036-3045页

作者： Li, JJ Thibault, P Bings, NH Skinner, CD Wang, C Colyer, C Harrison, J Natl Res Council Canada Inst Biol Sci Ottawa ON K1A 0R6 Canada Univ Alberta Dept Chem Edmonton AB T6G 2G2 Canada

This report describes the development of a compact and versatile, micromachined chip device enabling the efficient coupling of capillary electrophoresis to electrospray mass spectrometry (CE-ESMS). On-chip separation provides a convenient means of achieving rapid sample cleanup and resolution of multicomponent samples (typically 2-5 min) prior to mass spectral analysis. A low dead volume connection facilitating the coupling of microfabricated devices to CE-ESMS was evaluated using two different interfaces. The first configuration used disposable nanoelectrospray emitters directly coupled to the chip device via this low dead volume junction, thereby providing rapid separation of complex protein digests. The performance of this interface was compared with that of more traditional configurations using a sheath now CE-ESMS arrangement where a fused-silica capillary of varying length enabled further temporal resolution of the multicomponent samples. The sensitivity and analytical characteristics of these interfaces were investigated in both negative and positive ion modes using standard peptide mixtures. The separation performance for synthetic peptides using a chip coated with amine reagent ranged from 26 000 to 58 000 theoretical plates for a sheath flow CE-ESMS interface comprising a 15-cm CE column. Replicate injections of a dilution series of peptide standards provided detection limits of 15-400 nM without the use of on-line preconcentration devices. The reproducibility of migration time ranged from 0.9 to 1.5% RSD wheras RSDs of 5-10% were observed on peak areas. The application of these devices for the analysis of protein digests was further evaluated using on-line tandem mass spectrometry.

关键词：氨基酸序列电泳毛细管/仪器和设备电泳毛细管/方法外源凝集素类/化学外源凝集素类/代谢质谱分析法/仪器和设备质谱分析法/方法分子序列数据蛋白质类/分析蛋白质类/化学蛋白质类/代谢敏感性与特异性序列分析胰蛋白酶/化学胰蛋白酶/代谢

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Sample preparation for quantitation of tritium by accelerator mass spectrometry

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ANALYTICAL CHEMISTRY 2002年第24期74卷 6285-6290页

作者： Chiarappa-Zucca, ML Dingley, KH Roberts, ML Velsko, CA Love, AH Lawrence Livermore Natl Lab Hlth & Ecol Assessment Div Biol & Biotechnol Res Program Livermore CA 94551 USA Lawrence Livermore Natl Lab Ctr Accelerator Mass Spectrometry Livermore CA 94551 USA Woods Hole Oceanog Inst Natl Ocean Sci AMS Facil Woods Hole MA 02543 USA Univ Calif Berkeley Dept Civil & Environm Engn Berkeley CA 94720 USA

The capability to prepare samples accurately and reproducibly for analysis of tritium (H-3) content by accelerator mass spectrometry (AMS) greatly facilitates isotopic tracer studies in which attomole levels of H-3 can be measured in milligram-sized samples. A method has been developed to convert the hydrogen of organic samples to a solid, titanium hydride, which can be analyzed by AMS. Using a two-step process, the sample is first oxidized to carbon dioxide and water. In the second step, the water is transferred within a heated manifold into a quartz tube, reduced to hydrogen gas using zinc, and reacted with titanium powder. The H-3/H-1 ratio of the titanium hydride is measured by AMS and normalized to standards whose ratios were determined by decay counting to calculate the amount of H-3 in the original sample. Water, organic compounds, and biological samples with H-3 activities measured by liquid scintillation counting were utilized to develop and validate the method. The H-3/H-1 ratios were quantified in samples that spanned 5 orders of magnitude, from 10(-10) to 10(-15), with a detection limit of 3.0 x 10(-15), which is equivalent to 0.02 dpm tritium/mg of material. Samples smaller than 2 mg were analyzed following addition of 2 mg of a tritium-free-hydrogen carrier. Preparation of organic standards containing both C-14 and H-3 in 2-mg organic samples demonstrated that this sample preparation methodology can also be applied to quantify both of these isotopes from a single sample.

关键词： DNA/化学氢/分析肝/化学质谱分析法/仪器和设备质谱分析法/方法有机化学品/化学粒子加速器血浆/化学蛋白质类/化学甘油三酯类/化学氚/分析尿/化学

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Obtaining more accurate Fourier transform ion cyclotron resonance mass measurements without internal standards using multiply charged ions

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JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2000年第5期11卷 416-421页

作者： Bruce, JE Anderson, GA Brands, MD Pasa-Tolic, L Smith, RD Pacific NW Natl Lab Environm & Mol Sci Lab Richland WA USA

Space-charge effects produce frequency shifts in Fourier transform ion cyclotron resonance (FTICR) mass spectrometry and correction for these shifts is necessary for obtaining accurate mass measurements. We report a novel method for obtaining accurate mass calibration to correct for space-charge induced mass shifts without the requirement for internal calibrants. The new approach is particularly well suited for electrospray ionization-FTICR mass spectra that contain multiple charge states of the same molecular species This method, deconvolution of Coulombic affected linearity (DeCAL), is described and presented with several examples demonstrating the increased mass measurement accuracy obtained. DeCAL provides the basis for more routinely obtaining higher mass accuracy measurements in conjunction with chromatographic separations for complex mixture analysis, and obviates the need for internal calibration in many applications. (C) 2000 American Society for Mass Spectrometry.

关键词：算法校准回旋加速器傅里叶分析质谱分析法/仪器和设备质谱分析法/统计学和数值数据参考标准谱学傅里叶变换红外

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High-resolution Fourier transform ion cyclotron resonance mass spectrometry of humic and fulvic acids: Improvements and comparisons

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ANALYTICAL CHEMISTRY 2002年第2期74卷 413-419页

作者： Kujawinski, EB Hatcher, PG Freitas, MA Ohio State Univ Environm Mol Sci Inst Dept Chem Columbus OH 43210 USA

Full structural characteritation of complex mixtures such as humic acid extracts has been elusive because of insufficient compound resolution with conventional techniques. Using electrospray ionization coupled with Fourier transform ion cyclotron resonance mass spectrometry, we were able to resolve individual compounds within humic and fulvic acid mixtures (mass resolving power similar to80 000 at 300 m/z). We examined two samples in detail: (1) dissolved organic matter (primarily fulvic acids) from Suwannee River, GA, and (2) a humic acid extract from a degraded wood collected on Mt. Rainier, WA. Sample conditions (such as solvent, pH, and concentration) and instrument parameters (such as source voltages, trapping potentials, and excitation parameters) were optimized to yield the highest mass resolving power with the least mass discrimination in positive ion mode. High resolving power was achieved with low ion densities combined with coadding numerous scans. The increased resolution allowed molecular-level comparisons of the two samples which in turn could be used to estimate the relative similarity of individual compound distribution as well as an indication of the dominant diagenetic processes in the two source environments.

关键词：苯吡喃类/分析环境污染物/分析腐植质类/分析质谱分析法/仪器和设备质谱分析法/方法质谱分析法/标准

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Microfabricated devices for capillary electrophoresis-electrospray mass spectrometry

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ANALYTICAL CHEMISTRY 1999年第15期71卷 3258-3264页

作者： Zhang, B Liu, H Karger, BL Foret, F Northeastern Univ Barnett Inst Boston MA 02115 USA Northeastern Univ Dept Chem Boston MA 02115 USA

Two fundamental approaches for the coupling of microfabricated devices to electrospray mass spectrometry (ESI-MS) have been developed and evaluated. The microdevices, designed for electrophoretic separation, were constructed from glass by standard photolithographic/wet chemical etching techniques. Both approaches integrated sample inlet ports, preconcentration sample loops, the separation channel, and a port for ESI coupling. In one design, a modular, reusable microdevice was coupled to an external subatmospheric electrospray interface using a liquid junction and a fused silica transfer capillary. The transfer capillary allowed the use of an independent electrospray interface as well as fiber optic UV detection. In the second design, a miniaturized pneumatic nebulizer was fabricated as an integral part of the chip, resulting in a very simple device, The on-chip pneumatic nebulizer provided control of the flow of the electrosprayed liquid and minimized the dead volume associated with droplet formation at the electrospray exit port. Thus, the microdevice substituted for a capillary electrophoresis instrument and an electrospray interface-traditionally two independent components. This type of microdevice is simple to fabricate and may thus be developed either as a part of a reusable system or as a disposable cartridge, Both devices were tested on CE separations of angiotensin peptides and a cytochrome c tryptic digest. Several electrolyte systems including a transient isotachophoretic preconcentration step were tested for separation and analysis by an ion trap mass spectrometer.

关键词：氨基酸序列血管紧张素类/分析细胞色素c组/分析电泳毛细管/仪器和设备电泳毛细管/方法设备设计质谱分析法/仪器和设备质谱分析法/方法分子序列数据肽类/分析

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Simple cylindrical ion mirror with three elements

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JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2000年第9期11卷 759-764页

作者： Zhang, J Enke, CG Univ New Mexico Dept Chem Albuquerque NM 87131 USA

A new cylindrical ion mirror has been designed to create an electric field that is non-linear or curved along the flight path axis for general-purpose time-of-flight mass spectrometers. The inclusion of one or two grids is found to improve the radial field homogeneity especially around the aperture. Only three cylindrical electrodes are used in the design. Changing the electrode dimensions and voltages affects the electric field distribution. Once the electrode dimensions are fixed, there are only two adjustable parameters for achieving optimum nonlinear electric field shape. Resolving powers of 7000 and 16100 have been achieved with kinetic energy variations of 34 and 10.5%, respectively. Simulations show that the electric field homogeneity in the radial direction enables the use of ion beam diameters up to 15 mm with only modest: loss of resolving power. Increasing the mirror diameter could further increase the practical ion beam diameter. This article details the electric field distribution within the cylindrical mirror in both axial and radial directions. The voltages of the middle and rear electrodes affect the resolving power and the kinetic energy range over which focus can be achieved. The predicted arrival time spread for a single mit value is narrower than that caused by the turn-around time of ions in a gas-phase ion source. In this case, the broad energy range over which good focus is achieved enables the use of higher extraction fields for turn-around time reduction. (C) 2000 American Society for Mass Spectrometry.

关键词：化学物理电磁场质谱分析法/仪器和设备

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Simple geometry gridless ion mirror

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JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2000年第9期11卷 765-769页

作者： Zhang, J Gardner, BD Enke, CG Univ New Mexico Dept Chem Albuquerque NM 87131 USA

A gridless variation of the cylindrical ion mirror has been designed to create an electric field that is nonlinear in the axial direction and nearly homogeneous in the radial direction. The designs may include one or two chambers that consist of truncated cones. This new design concept yields ion mirrors with improved energy focusing over conventional single-field and multiple-field mirrors. Conventionally, ion mirrors with nonlinear field gradient use multiple diaphragm electrodes to which distinct voltages are applied. In this work, optimized nonlinear field distributions are achieved through shaping only two or three electrodes and applying only one or two voltages on the electrodes. The designs presented here offer high resolving power and low ion dispersion. SIMION simulations of performance from the ion source to the detector demonstrate resolving powers of 11000 and 1750 for ions with kinetic energy variations of 7.5% and 23.6%, respectively. (C) 2000 American Society for Mass Spectrometry.

关键词：化学物理电磁场质谱分析法/仪器和设备

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