长白山白眉蝮蛇蛇毒酶的基质辅助激光解吸质谱分析

用基质辅助激光解吸飞行时间质谱法对长白山眉蝮蛇蛇毒所含４种主要酶：磷脂酶Ａ２,精氨酸酯酶,纤溶酶及Ｌ－氨基酸氧化酶进行了纯度鉴定和分子量测定,结果表明ＭＡＬＤＩ－ＴＯ－ＦＭＸ具有灵敏度高,分辨能力强,分析时间短及样品用量少等优点。用ＭＡＬＤＩ－ＴＯＦＭＳ法分析蛇毒酶的纯度和分子量简捷,快速且重现性好,是ＳＤＳ聚丙烯酰胺凝胶电泳所无法比拟的。     

白眉蝮蛇蛇毒和蛇毒酶的基质辅助激光解吸电离飞行时间质谱法研究

应用基质辅激光解吸电离飞行时间质谱（ＭＡＬＤＩ－ＴＯＦ－ＭＳ）法对长白山眉蝮蛇蛇毒和纯化得到的两种蛇毒酶进行了研究,得到了它们的分子质量并验证了纯度。同时还考察了不同产地的蛇毒、蛇毒蛋白浓度以及基质对分析结果的影响,实验结果表明ＭＡＬＤＩ－ＴＯＦ－ＭＳ法是检测蛋白纯化过程和分析蛋白相对分子质量十分有效的手段。     

稀土富勒烯提取液的激光解吸飞行时间质谱研究

采用激光解吸飞行时间质谱对含镧(La)、铈(Ce)、镨(Pr)、钕(Nd)、钐(Sm)、铕(Eu)、钆(Gd).铽(Tb)、镝(Dy)、钬(Ho)、铒(Er)、铥(Tm)、镱(Yb)等13种稀土富勒烯的提取液进行了研究.考察了正负谱、激光强度、底物以及质量歧视对分析结果的影响,并由此确定了最佳分析条件.结果表明,提取液中除了空心富勒烯外,还存在较多量的稀土富勒烯.通过对它们谱峰相对强度之间的比较,探讨了不同稀土元素嵌入富勒烯球笼的结构稳定性及溶解性能的差别以及产生这种差别的可能原因.     

富勒醇的直接激光解吸飞行时间质谱分析

采用激光解吸电离飞行时间质谱对富勒醇样品进行研究,并与富勒烯标准品的质谱特征比较,以正负离子模式联合检测方法考察其特征结构。结果显示,正离子模式下,富勒醇碳笼易为规律性的碎裂峰,负离子模式下,则保留碳笼主体结构的特征峰,而富勒烯的碳笼结构在两种模式下不发生变化。表明该方法可以方便、快速地鉴别富勒醇的结构。采用该方法对富勒醇在二甲基亚砜(DMSO)中的稳定性进行分析,结果发现富勒醇可稳定存在于DMSO溶剂中,用于碱式反应条件下合成富勒醇的鉴别与条件筛选,选择反应碱的最佳浓度为1.0 g/mL。     

激光解吸电离飞行时间质谱下的银簇行为

近年来,对金属簇的研究已成为化学与物理学中最活跃的研究领域之一［１］．金属簇被认为是介于单个原子与固体之间的中间相［２］．深入地研究其结构、形成机理及物理与化学行为,对于寻找新的催化剂［３］,重新认识气相化学与凝聚相化学的关系［４］,都有非常重要的意...     

基体辅助激光解吸电离飞行时间质谱用于寡糖的分析

将基体辅助激光解吸电离飞行时间质谱这种新兴的质谱方法用于植物中寡糖的分析。比较了不同的样品制备方法和检测方法对分析结果的影响,给出各寡糖样品的分子量分布,单体和端基基团的分子量。     

稠环齐聚物结构的激光解吸电离飞行时间质谱表征

应用激光解吸电离飞行时间质谱对几种不同结构的吡嗪稠环齐聚物进行了表征.样品溶解在二甲基亚砜中,以正离子方式记录谱图,结果发现除了产生目标化合物的质子化的分子离子峰外,还产生了少量的碎片分子离子峰.结果表明激光解吸电离飞行时间质谱能有效地、快速准确地给出这类化合物的分子离子峰,为吡嗪类稠环齐聚物的研究提供了有效的表征方法.     

壳聚糖的基质辅助激光解吸电离飞行时间质谱分析

利用基质辅助激光解吸电离飞行时间质谱(MALDI-TOF-MS)分析甲壳素脱乙酰化降解产物——壳聚糖,对基质、制样方法等影响MALDI-TOF-MS测定结果的因素进行了研究。实验发现,以2,5-二羟基苯甲酸(DHB)为基质,二次结晶法制样分析壳聚糖,既获得了壳聚糖的分子量信息,又可以推断壳聚糖的脱乙酰度,对壳聚糖的制备及其质量与性能控制有着十分重要的指导意义。     

应用激光解吸质谱和十二烷基硫酸钠—聚丙烯酰胺凝胶电泳分析蛇毒？…

应用基质辅助激光解吸电离飞行时间质谱（ＭＡＬＤＩ－ＴＯＦ－ＭＳ）和ＳＤＳ－聚丙烯酰胺凝胶电流对吉林省两地市的同种白眉蝮蛇蛇毒中具有抗栓塞药效的精氨酸酯酶进行了分析了分析和比较。ＭＡＬＤＩ－ＴＯＦ－ＭＳ法具有快速、准确度高、灵敏度高的优点,两种方法结合,互为补充,取得了令人满意的结果。ＭＡＬＤＩ－ＴＯＦ－ＭＳ完全可以直接用作蛇毒成分分离过程中重要的研究手段。     

基体辅助激光解吸电离飞行时间质谱分析糖类的基体

糖类物质极性高、难挥发、热不稳定,其中多糖还具有相对分子质量分布发散的性质,其质谱表征比较困难。基体辅助激光解吸电离飞行时问质谱(matrix-assisted lazer desorption／ionization time-of-flight mass spectrometry．MALDI-TOFMS)灵敏、快速,对杂质的包容性强、分析的质量范围大,能够对糖类尤其是非衍生化糖进行直接分析。近年来,MALDI-TOFMS的发展已使糖类物质的分析达到一个新的水平。由于基体在MALDI-TOFMS分析中起着至关重要的作用,而研制开发和使用各种有效新基体也一直是MALDI-TOFMS分析的聚焦点,本文综述近10年MALDI-TOFMS分析糖类所用的基体。     

表面活性剂的基体辅助激光解吸电离/质谱分析表征

利用基体辅助激光解吸电离／质谱（MALDI－MS）技术对表面活性剂的分析表征进行了详细研究。以2，5－二羟基苯甲酸作为基体，考察MALDI样品制备方法如液滴干燥法、快速干燥法及三明治法对测定结果的影响，发现三明治方法更适合表面活性剂的分析。MALDI可以准确测定离子型表面活性剂的分子量，同时对于非离子型表面活性剂，还可以测定其平均聚合度和分子量的分布。     

金黄色葡萄球菌及其甲氧苯青霉素耐药性的MALDI-TOF MS鉴定

用MALDI－TOS MS细菌指纹图谱鉴定细菌，建立区分金黄色葡萄球菌甲氧苯青霉素耐药株和敏感株的MALDI－TOF MS分析方法，检测了76株从临床标本中分离得到的金黄色葡萄球菌，用软件进行聚类分析，以nuc(耐热核酸酶）基因和mecA(耐药）基因聚合酶链反应（PCR）检测结果为参照，74％的菌株经MALDI－TOF MS给出了正确的鉴定结果；金黄色葡萄球菌甲氧苯青霉素耐药株和敏感株的质谱图有很大差别，各自有其特征峰；经过软件聚类分析，76株实验菌株划敏感群和耐药群；与PCR检测结果对照，有7株菌PCR检测mecA基因为阴性，而经MALDI－TOF MS鉴定为耐药株，表型鉴定表明其中有5株为敏感株；利用细菌指纹图谱和数据库检索对大多数菌株实现了正确鉴定；MALDI－TOF MS分辨率高，甚至可以区分株间的差异，实现了区分金黄色葡萄球菌甲氧苯青霉素耐药株和敏感株；结果表明MALDI－TOF MS提供了一个很有前景的鉴定细菌的快速方法。     

Online Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry with In situ Mixing

Online matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) is reported with in situ matrix/analyte aerosol mixing. The analyte and matrix were dissolved in separate solvents and pneumatically atomized into particles. Continuous flows of analyte particles and matrix droplets in nitrogen were mixed in a tee. The resulting particles were sampled using a nozzle, focused into a beam with an aerodynamic lens system, and vertically deposited continuously on a movable target. The matrix/analyte mixture was desorbed/ionized using a 266 nanometers pulsed laser at an incident angle of 45°. The nascent ions were analyzed using reflectron TOF MS. The performance of online MALDI-TOF MS was evaluated by the analysis of palmityl palmitate with the lithium salt of 2, 4-dihydroxybenzoic acid as the matrix. Strong and stable MALDI signals of palmityl palmitate were obtained. The matrix solvent mixture and the analyte concentration were optimized and the results demonstrate the development of an alternative for online MALDI analysis.     

α-羟基-β-对甲苯磺酰氨基羧酸甲酯的质谱研究

氨基酸是蛋白质的基本组成单元,在有机合成及生物代谢中都是十分重要的物质。特别是α-羟基-β-氨基酸是一些重要生物活性物质的结构单元,例如著名的抗癌药紫杉醇的侧链。本文讨论5个α-羟基-β-氨基酸衍生物在EI和MALDI-TOF条件下的质谱性质。     

Do collisions inside the collision cell play a relevant role in CID‐LIFT experiments?

Collision experiments are a valid approach to characterize the ionic species generated by matrix assisted laser desorption ionization (MALDI). When a time-of-flight analyzer is employed, three different approaches are available for these experiments: the postsource decay (PSD), the LIFT and the MALDI-TOF/TOF. The last two are of particular interest because of the overcoming of the PSD problems related to mass calibration of the product ion spectra. Experiments performed by LIFT on linear or cyclic peptides, in presence or in absence of collision gas in the collision cell, gave evidence of an unexpected behavior: the two spectra were practically superimposable, and in the former case only a few new fragmentation channels were activated with low yield. These results mean that the selected ion exhibits a large amount of internal energy, capable of promoting fragmentation processes in the time window corresponding to the flight time between ion source and the acceleration electrode placed after the collision cell. Experiments performed by varying the plume density show that this internal energy uptake occurs in the expanding plume, through multiple collisions. The LIFT data have been compared with those achieved by collisions of ESI-generated [MH](+) ions of angotensin II performed under 'in-source' conditions and by triple-quadrupole experiments. The obtained results show a strong similarity among the spectra, indicating that the internal energy uptake in a MALDI source is comparable with that of 40-eV ions colliding with Ar in a triple-quadrupole instrument.     

Mass spectrometric characterization of low-molecular-mass color pI markers and their use for direct determination of pI value of proteins

The use of low-molecular-mass color pI markers for the determination of pI values of proteins in gel isoelectric focusing (IEF) in combination with mass spectrometry is described. Different types of substituted phenols of known pI values within the mass range 250-400 were used here as pI markers. The pure, synthesized pI markers were studied by MALDI-TOF/TOF MS. Fragmentation studies of the pI markers were also performed. Only stable and well-characterized pI markers were used in this work. The selected pI markers were mixed with proteins, deposited on a gel and separated in a pH gradient. Color pI markers enable supervision of progress of the focusing process and also estimation of the position of the invisible focused bands. The separated bands of the pI markers (containing separated proteins) were excised, and the pI markers were eluted from each gel piece by water/ethanol and identified by MALDI-TOF/TOF MS. From the washed gel pieces the remaining carrier ampholytes were then washed out and proteins were in-gel digested with trypsin. The obtained peptides were measured by MALDI-TOF/TOF MS and the proteins identified via a protein database search. This procedure allows avoiding time-consuming protein staining and destaining procedures, which shortens the analysis time roughly by half. For comparison, IEF gels were stained with Coomassie Brilliant Blue R 250 and proteins in the gel bands were identified according to the standard proteomic protocol. This work has confirmed that our approach can give information about the correct pI values of particular proteins and shorten significantly the time of analysis.     

Fusaricidins from Paenibacillus polymyxa M‐1, a family of lipohexapeptides of unusual complexity—a mass spectrometric study

Paenibacillus polymyxa are rhizobacteria with a high potential to produce natural compounds of biotechnological and medical interest. Main products of P . polymyxa are fusaricidins, a large family of antifungal lipopeptides with a 15‐guanidino‐3‐hydroxypentadecanoic acid (GHPD) as fatty acid side chain. We use the P . polymyxa strain M‐1 as a model organism for the exploration of the biosynthetic potential of these rhizobacteria. Using matrix‐assisted laser‐desorption/ionization time‐of‐flight mass spectrometry (MALDI‐TOF MS) about 40 new fusaricidins were detected which were fractionated by reversed‐phase (rp) HPLC. Their structure was determined by MALDI‐LIFT‐TOF/TOF fragment analysis. The dominant fragment in the product ion spectra of fusaricidins appeared at m /z 256.3, 284.3 and 312.4, respectively, indicating variations in their fatty acid part. Two new subfamilies of fusaricidins were introduced which contain guanidino‐3‐hydroxyhepta‐ and nonadecanoic acid as fatty acid constituents. Apparently, the end‐standing guanidine group is not modified as shown by direct infusion nano‐electrospray ionization mass spectrometry (nano‐ESI MS). The results of this study suggest that advanced mass spectrometry is the method of choice for investigating natural compounds of unusual diversity, like fusaricidins. Copyright © 2016 John Wiley & Sons, Ltd.     

同位素质谱和无机质谱

本文是《分析试验室》定期评述中“同位素质谱和无机质谱”的第四篇评述，评述的范围是１９９４年１１月至１９９６年１０月我国气体同位素质谱，热电离同位素质谱，加速器质谱，火花源质谱，电感耦合等离子体质谱，辉光放电质谱，同位素稀释质谱，二次离子质谱，激光共振电离子飞行时间质谱，电子探针，质子探针，激光探针和它们在地学，核科学，环境科学，材料学，计理学，医学和生命科学中的应用，引用文献１４９篇。     

MALDI-TOF质谱表征聚芳醚酮环状低聚物及其组分分布

应用介质辅助激光解吸离子化飞行时间质谱(MALDI-TOFMS),以二羟基苯甲酸为介质、N₂(337nm)为激光源,对两种聚芳醚酮环状低聚物的结构进行了确认,研究了环状低聚物不同聚合度组分的分布规律,并且与GPC质量分析法作了比较,实验结果表明,MALDI-TQF质谱是分析环状低聚物的准确、快速的工具之一.