International Journal of Mass Spectrometry最新文献_第7页

Structural analysis of echinocandins via high-performance liquid chromatography-quadrupole/time-of-flight-tandem mass spectrometry 高效液相色谱-四极杆/飞行时间串联质谱法分析棘白菌素的结构

IF 1.6 3区化学 Q3 PHYSICS, ATOMIC, MOLECULAR & CHEMICAL

International Journal of Mass Spectrometry

Pub Date : 2025-09-01 Epub Date: 2025-06-05 DOI: 10.1016/j.ijms.2025.117475

Hanzhi Zhang , Xiakun Wang , Bin Xu , Zhenhua Tian , Yu Luo , Zhijun Tang , Wen Liu

Herein, the structures of echinocandins were analyzed by high-performance liquid chromatography-quadrupole/time-of-flight-tandem mass spectrometry (HPLC-Q/TOF-MS/MS). The echinocandin components were separated by using a Diamonsil Plus C18 column (5 μm, 4.6 mm × 250 mm), with 0.1 % formic acid in water as mobile phase A and 0.1 % formic acid in acetonitrile as mobile phase B under gradient elution. A systematic strategy for the structural characterization of echinocandin B, which is the main component of echicandins, is presented based on the accurate molecular mass and diagnostic ions obtained from both adduct ions [M+H]⁺ and [M+Na]⁺ as precursor ions. In the three fragmentation pathways obtained from the precursor ion of [M+H]⁺, echinocandins and its fragment ions produced continuous dehydrated ions ([M-nH₂O + H]⁺, n = 1, 2, 3, 4). The N-terminal fatty acyl (FA) connecting to the ornithine derivative transferred to the amino group of the proline derivative during fragmentation. Different characteristic ions, depending on the number of hydroxyls (0, 1, 2) on the ornithine derivative of different echinocandin analog. Moreover, the threonine residues underwent the neutral consecutive loss of acetaldehyde from the [M+Na]⁺ precursor ion. The [M+H]⁺ and [M+Na]⁺ echinocandin precursor ions respectively lost 1-(4-hydroxyphenyl)ethane-1,2-diol and 2-hydroxy-2-(4-hydroxyphenyl)acetaldehyde from the homotyrosine residues to generate different fragmentation ions. Thirteen echinocandin analogs were identified, including echinocandin C, echinocandin D, and echinocandin B variants with different FA and amino acid compositions.

采用高效液相色谱-四极杆/飞行时间串联质谱（HPLC-Q/TOF-MS/MS）分析棘白菌素的结构。采用Diamonsil Plus C18色谱柱（5 μm, 4.6 mm × 250 mm），以0.1%甲酸水溶液为流动相a， 0.1%甲酸乙腈为流动相B，梯度洗脱分离棘白菌素。本文基于[M+H]+和[M+Na]+加合离子作为前体离子获得准确的分子质量和诊断离子，提出了一种系统的表征棘白素B结构的策略。在由[M+H]+前体离子得到的3条破碎途径中，棘白菌素及其碎片离子产生连续的脱水离子（[M- nh2o +H]+, n = 1,2,3,4）。连接鸟氨酸衍生物的n端脂肪酰基（FA）在断裂过程中转移到脯氨酸衍生物的氨基上。不同的特征离子，取决于羟基（0、1、2）的数目对不同棘白素类似物的鸟氨酸衍生物。此外，苏氨酸残基经历了[M+Na]+前体离子乙醛的中性连续损失。[M+H]+和[M+Na]+棘白菌素前体离子分别从同型酪氨酸残基中失去1-（4-羟基苯基）乙烷-1,2-二醇和2-羟基-2-（4-羟基苯基）乙醛，生成不同的断裂离子。鉴定出13种棘白菌素类似物，包括棘白菌素C、棘白菌素D和棘白菌素B，它们具有不同的FA和氨基酸组成。

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引用次数: 0

Chirality effects on the intrinsic acidity of isomeric tripeptides containing a D/L-Cysteine on the N-terminus: CAA and dCAA 手性对n端含D/ l -半胱氨酸的异构体三肽固有酸度的影响：CAA和dCAA

IF 1.6 3区化学 Q3 PHYSICS, ATOMIC, MOLECULAR & CHEMICAL

International Journal of Mass Spectrometry

Pub Date : 2025-08-01 Epub Date: 2025-05-20 DOI: 10.1016/j.ijms.2025.117472

Shiyuan Wang, Zachary Buen, Kimberlyann R. Harvey, Yuntao Zhang, Jianhua Ren

Chirality effects on the intrinsic gas-phase acidity of oligopeptides have been studied using a pair of stereoisomeric tripeptides consisting of a D/L-cysteine (C) and two residues of alanine (A): CAA and ^dCAA, where the C-terminus is amidated. Mass spectrometry measurements through bracketing via collision-induced dissociation clearly show that CAA is a stronger gas-phase acid than ^dCAA. Quantitative values of the acidity were determined using the extended Cooks kinetic method. The resulting deprotonation enthalpy (Δ_acidH) for CAA is 326.2 kcal/mol (1364.7 kJ/mol) and for ^dCAA it is 326.8 kcal/mol (1367.6 kJ/mol). The corresponding gas-phase acidity (Δ_acidG) for CAA is 321.3 kcal/mol (1344.2 kJ/mol) and for ^dCAA it is 322.0 kcal/mol (1347.3 kJ/mol). Changing the N-terminal cysteine from the L-form to the D-form reduces the gas-phase acidity by about 0.6 kcal/mol (2.5 kJ/mol). Extensive conformational searches followed by quantum chemical calculations at the ωB97X-D/6-311+G(d,p) level of theory yielded a set of lowest energy conformations for each peptide species. Theoretical gas-phase acidities calculated using the Boltzmann averaged conformational contributions are in good agreement with the experimental data. The shift in the acidity is likely due to the conformational effect induced by D-cysteine, which increases the stability of the neutral ^dCAA, and hence reduces its acidity. A chirality change on a single amino acid can have a noticeable effect on the biochemical properties of peptides and proteins.

用一对由D/ l -半胱氨酸(C)和丙氨酸(a)的两个残基：CAA和dCAA组成的立体异构体三肽研究了手性对寡肽固有气相酸度的影响，其中C端被修饰。通过碰撞诱导解离进行的质谱测量清楚地表明，CAA是比dCAA更强的气相酸。用扩展库克斯动力学法测定了酸度的定量值。CAA的脱质子焓（ΔacidH）为326.2 kcal/mol (1364.7 kJ/mol)， dCAA的脱质子焓为326.8 kcal/mol （1367.6 kJ/mol）。相应的CAA气相酸度（ΔacidG）为321.3 kcal/mol (1344.2 kJ/mol)， dCAA气相酸度为322.0 kcal/mol （1347.3 kJ/mol）。将n端半胱氨酸从l型转变为d型，可使气相酸度降低约0.6 kcal/mol （2.5 kJ/mol）。广泛的构象搜索之后，在ωB97X-D/6-311+G（d,p）理论水平上进行量子化学计算，得出了每种肽种的一组最低能量构象。用玻尔兹曼平均构象贡献计算的理论气相酸度与实验数据吻合良好。酸度的变化可能是由于d -半胱氨酸引起的构象效应，它增加了中性dCAA的稳定性，从而降低了它的酸度。单个氨基酸的手性变化会对多肽和蛋白质的生化特性产生显著影响。

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引用次数: 0

Miniature APCI ion source using AC corona discharge in a PFA tube: its application to the analysis of low-volatility compounds coupled with heat pulse desorption mass spectrometry (HPD/MS) PFA管交流电晕放电微型APCI离子源：热脉冲解吸质谱（HPD/MS）联用在低挥发性化合物分析中的应用

IF 1.6 3区化学 Q3 PHYSICS, ATOMIC, MOLECULAR & CHEMICAL

International Journal of Mass Spectrometry

Pub Date : 2025-08-01 Epub Date: 2025-05-03 DOI: 10.1016/j.ijms.2025.117461

Stephanie Rankin-Turner , Satoshi Ninomiya , Haruo Shimada , Kazumasa Kinoshita , Kenzo Hiraoka

DC corona discharge has long been used as the APCI ion source. In 2013, Habib et al. first proposed AC corona discharge as an APCI ion source and found that it is superior to DC as an ambient ion source [1]. In this study, an ion source using AC corona enclosed in a PFA (perfluoroalkoxy) tube (i.d.: 2 mm) was developed as a miniature APCI ion source coupled with heat pulse desorption mass spectrometry (HPD-MS) and used for the desorption of low-volatility compounds. Diverse materials were introduced, demonstrating the potential to apply the miniature ion source to gas-phase analytes, liquid samples, and solid materials in their native state. The modified technique was utilized in the analysis of a range of samples, including solid and liquid pharmaceuticals, food products, plant material, insects, and human biofluids, highlighting the wide applicability of the miniature APCI ion source across diverse sample types and fields of study.

直流电晕放电长期以来一直被用作APCI离子源。2013年，Habib等人首次提出交流电晕放电作为APCI离子源，并发现其作为环境离子源[1]优于直流。本研究采用全氟烷氧基（PFA）管（直径：2mm）封装的交流电晕离子源作为微型APCI离子源，与热脉冲解吸质谱（HPD-MS）相结合，用于低挥发性化合物的解吸。介绍了多种材料，展示了将微型离子源应用于气相分析物，液体样品和天然状态下的固体材料的潜力。改进后的技术被用于分析一系列样品，包括固体和液体药物、食品、植物材料、昆虫和人类生物流体，突出了微型APCI离子源在不同样品类型和研究领域的广泛适用性。

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引用次数: 0

Impact of glucagon oxidation on fibril formation 胰高血糖素氧化对纤维形成的影响

IF 1.6 3区化学 Q3 PHYSICS, ATOMIC, MOLECULAR & CHEMICAL

International Journal of Mass Spectrometry

Pub Date : 2025-08-01 Epub Date: 2025-05-14 DOI: 10.1016/j.ijms.2025.117468

Aleksandra Antevska , Gaoyuan Lu , Emmanuel Nkyaagye , Sarah S. Hirschbeck , Connor C. Long , Lingjun Li , Thanh D. Do

Glucagon structural dynamics is crucial for its function and pathology, yet its oligomerization and fibrillization mechanisms remain unclear. The early assembly of glucagon into fibrils is a critical process that can be perturbed by oxidation at key residues. In this study, we systematically tracked the oligomer formation of native glucagon up to the decamer level, revealing that glucagon undergoes oxidation at tryptophan and methionine—residues essential to its steric zipper structure. Our findings also indicate that oxidation exerts a dual effect on glucagon fibrillation. At low concentrations, oxidation partially unfolds glucagon's α-helix, facilitating hetero-oligomer formation between oxidized and native peptides, which promotes further oligomerization and unfolding. However, at high concentrations, oxidized glucagon fails to self-assemble into fibrils and appears more susceptible to degradation. Chromatographic analysis differentiates native and oxidized glucagon, highlighting increased polarity and multiple elution peaks indicative of diverse oxidative states, while mass spectrometry confirms site-specific modifications that influence structural transitions. These results emphasize the fine balance between oxidation and self-assembly, with implications for glucagon's therapeutic stability. An understanding of oxidation-induced aggregation dynamics is essential for developing stable glucagon formulations, underscoring the importance of controlling oxidative conditions to preserve their functionality and efficacy.

胰高血糖素的结构动力学对其功能和病理至关重要，但其寡聚化和纤化机制尚不清楚。胰高血糖素早期组装成原纤维是一个关键过程，可被关键残基的氧化所干扰。在这项研究中，我们系统地追踪了天然胰高血糖素低聚物的形成，直到十聚体水平，揭示了胰高血糖素在其立体拉链结构所必需的色氨酸和蛋氨酸残基处经历氧化。我们的发现也表明氧化对胰高血糖素纤颤有双重作用。在低浓度下，氧化作用使胰高血糖素的α-螺旋部分展开，促进氧化肽和天然肽之间形成异聚物，从而促进进一步的寡聚和展开。然而，在高浓度下，氧化的胰高血糖素不能自组装成原纤维，似乎更容易降解。色谱分析区分天然胰高血糖素和氧化胰高血糖素，强调极性增加和多个洗脱峰表明不同的氧化状态，而质谱分析证实了影响结构转变的位点特异性修饰。这些结果强调氧化和自组装之间的良好平衡，与胰高血糖素的治疗稳定性的含义。了解氧化诱导的聚集动力学对于开发稳定的胰高血糖素配方至关重要，强调控制氧化条件以保持其功能和功效的重要性。

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引用次数: 0

An in situ analysis of the components of HTS vapor using a home-made high-temperature time-of-flight mass spectrometer 利用自制的高温飞行时间质谱仪对高温高温蒸汽组分进行了原位分析

IF 1.6 3区化学 Q3 PHYSICS, ATOMIC, MOLECULAR & CHEMICAL

International Journal of Mass Spectrometry

Pub Date : 2025-08-01 Epub Date: 2025-05-21 DOI: 10.1016/j.ijms.2025.117471

Zejie Fei, Min Ge, Yuan Qian, Hongtao Liu, Yuanyuan Tang

The aim of this study was to propose the decomposition mechanism of heat transfer salt (HTS or Hitec salt) using a high-temperature furnace coupled with a time-of-flight mass spectrometer (TOF-MS). The decomposition process was systematically investigated in a vacuum environment at temperatures of 45 °C, 80 °C, 150 °C, 200 °C, 220 °C and 280 °C. The thermal decomposition of HTS initiated at and above 200 °C, which was slightly higher than its melting point of 142 °C. The main products resulting from the thermochemical reactions of nitrate/nitrite were NO and N₂ respectively, followed by N₂O. These findings revealed an unconventional reaction pathways for HTS decompositions as it contradicted the common assumption that O₂ or NO₂ would be present during this process. These new evidences further support the existence of intermediate species, such as superoxide and peroxide ions, in the molten salts during the initial thermal-chemical reaction process involving nitrite/nitrate salts.

本研究的目的是利用高温炉和飞行时间质谱联用仪（TOF-MS）研究传热盐（HTS或Hitec盐）的分解机理。在45°C， 80°C, 150°C, 200°C， 220°C和280°C的真空环境下系统地研究了分解过程。HTS的热分解始于200℃及以上，略高于其熔点142℃。硝酸根/亚硝酸盐热化学反应的主要产物为NO和N2，其次为N2O。这些发现揭示了HTS分解的非常规反应途径，因为它与O2或NO2在此过程中存在的普遍假设相矛盾。这些新证据进一步支持了在亚硝酸盐/硝酸盐初始热化学反应过程中熔盐中存在超氧化物和过氧化物离子等中间物质。

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引用次数: 0

Determining β-monosaccharide head group composition with high-resolution cyclic ion mobility separations coupled to tandem mass spectrometry as a first step for unknown cerebroside analysis 高分辨率环离子迁移分离耦合串联质谱法测定β-单糖头基团组成作为未知脑苷分析的第一步

IF 1.6 3区化学 Q3 PHYSICS, ATOMIC, MOLECULAR & CHEMICAL

International Journal of Mass Spectrometry

Pub Date : 2025-08-01 Epub Date: 2025-04-25 DOI: 10.1016/j.ijms.2025.117459

Cameron N. Naylor, Gabe Nagy

Cerebrosides, a class of biologically important lipids, are comprised of a monosaccharide head group along with their ceramide tail. However, their accurate characterization is challenging because of the isomerism in both the tail, from potential double bond positioning, or in the head from monosaccharide composition and α/β anomericity. In this work, we focused on tackling the identification of the β-monosaccharide head group, as either glucose or galactose, in various cerebroside isomers as well as demonstrating how our methodology could be applied to unknowns found in a porcine extract. To achieve this, we performed collision-induced dissociation prior to cyclic ion mobility separations to generate monosaccharide fragment ions from the starting cerebroside precursor ions. With this pre-cIMS CID approach, we observed that the cIMS separations of the fragment ions were diagnostic of the β-monosaccharide head group composition (i.e., glucose versus galactose), regardless of the ceramide tail length. From there, we demonstrated an example of how this methodology could also be applied to cerebrosides found in a porcine extract and a framework for how this approach could be added to existing workflows in developing collision cross section databases. Overall, we envision that our developed pre-cIMS CID-based approach will be a complementary and orthogonal tool to existing ones in glycolipidomics workflows.

脑苷是一类生物学上重要的脂类，由单糖头部基团及其神经酰胺尾部组成。然而，它们的准确表征是具有挑战性的，因为在尾部，从潜在的双键定位，或在头部，从单糖组成和α/β异构性。在这项工作中，我们专注于在各种脑苷异构体中识别β-单糖头基团，即葡萄糖或半乳糖，并展示了我们的方法如何应用于猪提取物中发现的未知物质。为了实现这一点，我们在循环离子迁移分离之前进行了碰撞诱导解离，从起始的脑苷前体离子产生单糖片段离子。通过这种预cIMS CID方法，我们观察到片段离子的cIMS分离可诊断β-单糖头基团组成（即葡萄糖与半乳糖），而与神经酰胺尾部长度无关。从那里，我们展示了一个如何将这种方法应用于猪提取物中发现的脑苷的例子，以及如何将这种方法添加到开发碰撞截面数据库的现有工作流程中的框架。总的来说，我们设想我们开发的基于cims前cidd的方法将成为糖脂组学工作流程中现有方法的互补和正交工具。

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引用次数: 0

Emissions of volatile organic compounds from COVID-19 response hospitals using mobile proton transfer reaction mass spectrometry observations in Wuhan in 2020 2020年武汉市新型冠状病毒肺炎应对医院挥发性有机物排放动态质子转移反应质谱分析

IF 1.6 3区化学 Q3 PHYSICS, ATOMIC, MOLECULAR & CHEMICAL

International Journal of Mass Spectrometry

Pub Date : 2025-08-01 Epub Date: 2025-05-05 DOI: 10.1016/j.ijms.2025.117460

Qu Liang , Xun Bao , Chenghua Qin , Qiangling Zhang , Xue Zou , Wei Xu , Chaoqun Huang , Chengyin Shen , Yannan Chu

To curb the rapid spread of the COVID-19, Wuhan was the first in the world to implement strict lockdown measures on January 23, 2020, and rapidly established several large hospitals. The extensive disinfection operations and daily activities within these hospitals led to the release of significant amounts of volatile organic compounds (VOCs). However, the composition and concentration characteristics of VOCs around these hospitals remain unclear. This study employed a self-developed mobile proton transfer reaction mass spectrometry (M-PTR-MS) system to conduct high spatiotemporal resolution mobile monitoring of VOCs in these hospitals in Wuhan from February 29 to March 15, 2020. The study compared the temporal and spatial variations in VOC across Wuhan, focusing on the frequency and concentration of VOC increases downwind of temporary hospital (Leishenshan Hospital), designated hospitals (Wuhan Xiehe Hospital, Wuhan Jinyintan Hospital), and shelter hospitals (Wuhan Keting Shelter Hospital, Hongshan Stadium Shelter Hospital). The results indicated that during the 14 days of effective mobile monitoring, the average concentration of total VOC (TVOC) in the first seven days was 13.39 % higher than in the latter seven days. Spatially, the average concentration of TVOC in the industrial areas north of the Yangtze River was 8.89 % higher than those in the non-industrial areas south of the river. Leishenshan Hospital exhibited the most diverse VOC composition and sources, with VOCs primarily originating from the fermentation and direct incineration of medical, waste within the hospital grounds and disinfectants. Downwind of the designated hospitals, VOCs related to industrial-source, disinfectants and waste were detected. Ethanol was detected downwind of all these hospitals. Waste generated by hospitals was a significant source of VOCs downwind of both temporary and designated hospitals. This study provides valuable technology for the research on VOC characteristics, disinfection efficacy evaluation, and environmental impact analysis during public health emergencies.

为遏制新冠肺炎疫情的快速传播，武汉于2020年1月23日在全球率先实施严格的封锁措施，并迅速建立了几家大型医院。这些医院内广泛的消毒操作和日常活动导致大量挥发性有机化合物（VOCs）的释放。然而，这些医院周围VOCs的组成和浓度特征尚不清楚。本研究采用自主研发的移动质子转移反应质谱（M-PTR-MS）系统，于2020年2月29日至3月15日对武汉市上述医院的VOCs进行了高时空分辨率的移动监测。本研究比较了武汉市各地区VOC的时空变化，重点研究了临时医院（雷神山医院）、定点医院（武汉协和医院、武汉金银坛医院）和方棚医院（武汉京亭方棚医院、红山体育馆方棚医院）顺风方向VOC增加的频率和浓度。结果表明：在有效移动监测的14 d内，前7 d总挥发性有机化合物（TVOC）平均浓度比后7 d高13.39%；从空间上看，长江以北工业区的TVOC平均浓度比长江以南非工业区高8.89%；雷神山医院挥发性有机化合物的组成和来源最为多样化，挥发性有机化合物主要来自医院场地内发酵和直接焚烧的医疗废物和消毒剂。在定点医院下风方向，检测到与工业源、消毒剂、废弃物有关的VOCs。所有这些医院的下风处都检测到乙醇。医院产生的废物是临时医院和指定医院顺风处挥发性有机化合物的重要来源。本研究为突发公共卫生事件中VOC特性研究、消毒效果评价及环境影响分析提供了有价值的技术手段。

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引用次数: 0

Effect of the Tyr5 and His6 substituent groups on the zinc affinities and conformational structures of the acetyl-His1-Cys2-Gly3-Pro4-X5-X6-Cys7 heptapeptides Tyr5和His6取代基对乙酰- his1 - cys2 - gly3 - pro4 - x5 - x6 - cys7七肽的锌亲和力和构象结构的影响

IF 1.6 3区化学 Q3 PHYSICS, ATOMIC, MOLECULAR & CHEMICAL

International Journal of Mass Spectrometry

Pub Date : 2025-07-01 Epub Date: 2025-04-23 DOI: 10.1016/j.ijms.2025.117458

Richmond A. Adomako, Michael B. Owusu, Rebekah Oberdick, Kwabena N. Senyah, Perfect Asare, Laurence A. Angel

In this study, we investigate the influence of the Tyr₅ and His₆ substituent groups on the zinc-binding affinities and conformational properties of a series of acetylated heptapeptides, acetyl-His₁-Cys₂-Gly₃-Pro₄-X₅-X₆-Cys₇ focusing on the impacts where X₅-X₆ are either Tyr₅-Gly₆, Tyr₅-His₆, Gly₅-Gly₆, or Gly₅-His₆. Utilizing traveling-wave ion mobility-mass spectrometry and molecular modeling techniques we analyze the zinc binding interactions and peptide coordination behavior. The zinc binding peptides (ZBPs) relative zinc affinities were measured across pH 5 to pH 10 by monitoring the solution-phase formation of the [ZBP+Zn(II)]⁻ complex by utilizing native MS in negative ion mode to preserve the solution-phase binding of Zn(II) to the peptides. Furthermore, their relative gas-phase Zn(II) affinities were measured using competitive threshold collision-induced dissociation (TCID) of the [ZBP+Zn(II)+NTA]⁻ complex, by modeling the two competing dissociation channels: [ZBP+Zn(II)]⁻ + NTA or [Zn(II)+NTA]⁻ + ZBP, where NTA is nitrilotriacetic acid. Our examinations also tested whether there was an effect of the formation of the [ZBP+Zn(II)+NTA]⁻ complexes from solutions at different pHs, before they are electrosprayed into the gas-phase for the TCID analyses. Both solution- and gas-phase measurements predicted the heptapeptide with the Gly₅-His₆ residues had the greatest zinc affinity and that the presence of Tyr₅ and His₆ altered the zinc affinity and induced distinct conformational changes due to changes in the coordination of the zinc. This research enhances our understanding of zinc-peptide interactions, with implications for the design of peptide-based metalloproteins, which may guide the design of novel ZBPs for therapeutic, biotechnological or environmental remediation applications.

在本研究中，我们研究了Tyr5和His6取代基对一系列乙酰化七肽乙酰基- his1 - cys2 - gly3 - pro4 -X5-X6- cys7的锌结合亲和性和构象性质的影响，重点研究了X5-X6为Tyr5- gly6、Tyr5-His6、Gly5-Gly6或Gly5-His6时的影响。利用行波离子迁移质谱和分子模型技术，我们分析了锌的结合相互作用和肽的配位行为。通过使用天然质谱在负离子模式下监测[ZBP+Zn(II)] -络合物的液相形成，以保持Zn（II）与肽的液相结合，测量了锌结合肽（ZBP）在pH 5至pH 10之间的相对锌亲和力。此外，通过模拟[ZBP+Zn(II)+NTA] -络合物的两个竞争解离通道：[ZBP+Zn(II)]−+NTA或[Zn(II)+NTA]−+ ZBP，其中NTA是硝化三乙酸，利用竞争阈值碰撞诱导解离（TCID）测量了它们的相对气相Zn（II）亲和度。我们的研究还测试了不同ph值溶液中[ZBP+Zn(II)+NTA]−络合物的形成是否有影响，然后将它们电喷涂到气相进行TCID分析。溶液和气相测量均预测Gly5-His6残基的七肽具有最大的锌亲和力，并且Tyr5和His6的存在改变了锌的亲和力，并由于锌的配位改变而引起明显的构象变化。这项研究增强了我们对锌-肽相互作用的理解，对设计基于肽的金属蛋白具有重要意义，这可能指导设计用于治疗、生物技术或环境修复的新型zbp。

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引用次数: 0

Approaches with different reaction gases for the determination of iron in rare earth samples based on on-mass mode by inductively coupled plasma tandem mass spectrometer 电感耦合等离子体串联质谱计在非质量模式下测定稀土样品中铁的方法

IF 1.6 3区化学 Q3 PHYSICS, ATOMIC, MOLECULAR & CHEMICAL

International Journal of Mass Spectrometry

Pub Date : 2025-07-01 Epub Date: 2025-04-14 DOI: 10.1016/j.ijms.2025.117456

Zhe Fang , Haizhou Wang , Lei Wang , Kai Li

The determination of iron using ICP-MS-MS is complicated due to the polyatomic spectral interferences, notably the ⁴⁰Ar¹⁶O⁺ on the abundant ⁵⁶Fe isotope. In this research, the utilization of three gases—helium, hydrogen, and methane—to accurately quantify iron was proposed using the on-mass mode by inductively coupled plasma tandem mass spectrometer. The conditions of the collision/reaction cell were optimized, particularly the gas flow rate and the hexapole bias voltage, for iron analysis. Different mechanisms, including collision and reactions like charge transfer reactions, hydrogen atom transfer reactions, and proton transfer reactions, were explored. In terms of sensitivity and background equivalent concentration (BEC), the hydrogen mode exhibited the highest sensitivity and the lowest BEC. The methane mode yields a comparable BEC to that of the hydrogen mode with a threefold reduction in sensitivity. The limit of quantification (LOQ) under the hydrogen reaction mode was as low as 0.028 μg/g.The analysis results of the national standard substance GBW07159 were in excellent agreement with the certified values, and the relative standard deviation (RSD) for n = 11 was less than 5 % in the three modes. The measured values and spiked recoveries for rare earth oxides were essentially consistent between the hydrogen and methane modes. Following validation, the hydrogen and methane reaction modes have been shown to accurately analyze iron in rare earth and rare earth oxides with high accuracy and stability, surpassing the helium mode in terms of collision mechanism.

ICP-MS-MS对铁的测定由于多原子光谱干扰，特别是对丰富的56Fe同位素的40Ar16O+的干扰，使测定变得复杂。本研究提出利用氦、氢、甲烷三种气体，利用电感耦合等离子体串联质谱仪的on-mass模式对铁元素进行精确定量。对碰撞/反应池的条件进行了优化，特别是气体流速和六极偏压。不同的机制，包括碰撞和反应，如电荷转移反应，氢原子转移反应，质子转移反应，进行了探索。在灵敏度和背景等效浓度（BEC）方面，氢模式灵敏度最高，BEC最低。甲烷模式产生了与氢模式相当的BEC，灵敏度降低了三倍。氢反应模式下的定量限低至0.028 μg/g。国家标准物质GBW07159的分析结果与认证值吻合良好，在n = 11的情况下，三种模式的相对标准偏差（RSD）均小于5%。稀土氧化物的测量值和加标回收率在氢模式和甲烷模式之间基本一致。经过验证，氢气和甲烷反应模式能够准确分析稀土和稀土氧化物中的铁，具有较高的准确性和稳定性，在碰撞机理上优于氦反应模式。

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引用次数: 0

Residue-specific pathways in peptide fragmentation: The role of aromatic side chain in a3 ion formation from b3 ion 肽破碎过程中的残基特异性途径：芳香侧链在由 b3 离子形成 a3 离子中的作用

IF 1.6 3区化学 Q3 PHYSICS, ATOMIC, MOLECULAR & CHEMICAL

International Journal of Mass Spectrometry

Pub Date : 2025-07-01 Epub Date: 2025-04-14 DOI: 10.1016/j.ijms.2025.117457

A. Emin Atik , Sila Karaca , Talat Yalcin

Peptide fragmentation chemistry is essential for the sequence elucidation of proteins through tandem mass spectrometry (MS/MS). In this study, we examine the gas-phase fragmentation of b₃ ions from model tripeptides under low-energy CID conditions, focusing on the pathway leading to the stable formation of a₃ ions from b₃ ions. The study utilized C-terminal amidated model tripeptides, including YGG-NH₂, GYG-NH₂, and GGX-NH₂, where X represents D, E, H, Q, C, S, F, and Y. Our results reveal that only tripeptides with phenylalanine (F) and tyrosine (Y) as the third residue yield a₃ ions upon b₃ ion fragmentation under the applied experimental conditions, suggesting a unique stabilizing role of aromatic side chains in facilitating this pathway. Our theoretical studies indicate that the a₃ ions from GGF-NH₂ and GGY-NH₂ preferentially adopt an energetically favored linear imine-protonated isomer, which is lower in energy by 3.29 kcal/mol and 4.17 kcal/mol, respectively, compared to their 7-membered ring isomers protonated at the ring imine. The latter structure has been previously assigned for the GGG sequence as a predominant structure, supported by IR spectroscopy and DFT calculations (JACS, 2010, 132, 14,766–14779). We proposed a plausible fragmentation mechanism for the a₃ ions based on the linear imine-protonated structure. These findings provide insights into residue-specific fragmentation mechanisms and enhance our understanding of peptide ion dissociation, particularly in small peptides.

肽片段化化学是通过串联质谱（MS/MS）分析蛋白质序列的必要条件。在本研究中，我们研究了低能CID条件下模型三肽中b3离子的气相破碎，重点研究了b3离子稳定形成a3离子的途径。本研究使用了C端修饰的模型三肽，包括YGG-NH2、GYG-NH2和GGX-NH2，其中X代表D、E、H、Q、C、S、F和Y。我们的研究结果表明，在应用实验条件下，只有苯丙氨酸(F)和酪氨酸(Y)作为第三个残基的三肽在b3离子断裂时产生a3离子，这表明芳香侧链在促进这一途径中具有独特的稳定作用。我们的理论研究表明，GGF-NH2和GGY-NH2中的a3离子优先采用能量有利的线性亚胺质子化异构体，与在环亚胺上质子化的7元环异构体相比，其能量分别低3.29 kcal/mol和4.17 kcal/mol。经红外光谱和DFT计算，后一种结构被认为是GGG序列的主要结构（JACS, 2010, 32, 14766 - 14779）。我们提出了一种基于线性亚胺质子化结构的a3离子断裂机理。这些发现提供了残基特异性断裂机制的见解，并增强了我们对肽离子解离的理解，特别是在小肽中。

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