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Li Y, Cavet G, Zare RN, Driver T. Fragment Correlation Mass Spectrometry Enables Direct Characterization of Disulfide Bond Cleavage Pathways of Therapeutic Peptides. Anal Chem 2024. [PMID: 39248333 DOI: 10.1021/acs.analchem.4c03202] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/10/2024]
Abstract
Therapeutic peptides that are connected by disulfide bonds are often difficult to analyze by traditional tandem mass spectrometry without chemical modification. Using fragment correlation mass spectrometry, we analyzed 56 pairs of fragment ions generated from an equimolar (10 μM) mixture of three cyclic peptides, achieving sequence coverage of 86%, 100%, and 75% for octreotide, desmopressin, and the structural analogue of desmopressin, respectively. In all detected fragment ion pairs, only 20% of the fragment ions are terminal ions, with most of the measured ions only detected by fragment correlation mass spectrometry. From the peak volumes in the covariance map, we calculated branching ratios of each disulfide bond fragmentation pathway, providing a direct measurement of the probability of each fragmentation without requiring alteration of the chemical structure of the analytes.
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Affiliation(s)
- Yangjie Li
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
| | - Guy Cavet
- Flatiron Bio, LLC, Palo Alto, California 94301, United States
| | - Richard N Zare
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
| | - Taran Driver
- Stanford PULSE Institute, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
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Yang X, Zhang L, Xia Y. Photochemical Disulfide-Ene Modification Enhances Protein Sequencing and Disulfide Mapping by Mass Spectrometry. Anal Chem 2021; 93:15231-15235. [PMID: 34751558 DOI: 10.1021/acs.analchem.1c04214] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
A new photochemical disulfide-ene reaction system capable of alkylating protein disulfide bonds in seconds has been established. The system is simple, containing acetone and isopropanol for disulfide reduction under 254 nm UV irradiation and norbornene as a highly efficient alkylation reagent. Enhanced characterization of disulfide-rich proteins with significantly shortened analysis time is demonstrated by coupling the reaction online with mass spectrometry.
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Affiliation(s)
- Xiaoyue Yang
- Department of Chemistry, Tsinghua University, Beijing 100084, China
| | - Longfei Zhang
- Department of Chemistry, Tsinghua University, Beijing 100084, China
| | - Yu Xia
- Department of Chemistry, Tsinghua University, Beijing 100084, China
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Li G, Delafield DG, Li L. Improved structural elucidation of peptide isomers and their receptors using advanced ion mobility-mass spectrometry. Trends Analyt Chem 2020. [DOI: 10.1016/j.trac.2019.05.048] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
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Zhuang M, Li H, Jiang J, Huang G. Reagent-free and pH-independent degradation of N-nitrosamines using electrons generated via corona discharge at ambient pressure. JOURNAL OF MASS SPECTROMETRY : JMS 2019; 54:141-147. [PMID: 30536522 DOI: 10.1002/jms.4318] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2018] [Revised: 10/30/2018] [Accepted: 11/27/2018] [Indexed: 06/09/2023]
Abstract
Traditional degradation methods for N-nitrosamines are either confined with acid solution or required for additional chemical reagents to guarantee high reaction efficiency. Herein, we demonstrate a facile and effective way for reagent-free and pH-independent degradation of N-nitrosamines, which was induced by free electrons generated via corona discharge at ambient pressure. The highly reactive free electron is produced in situ and responsible for degradation of three N-nitrosamines, which was also theoretically confirmed. N-nitrosamines were believed to be reduced by electrons and to form the radical anion, which underwent a selectively heterolytic cleavage of the N-NO bonds to form the corresponding secondary amines as the degradation products.
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Affiliation(s)
- Meihui Zhuang
- Hefei National Laboratory for Physical Sciences at the Microscale, School of Chemistry and Materials Science, University of Science and Technology of China (USTC), Hefei, 230026, PR China
| | - Hongbao Li
- Hefei National Laboratory for Physical Sciences at the Microscale, School of Chemistry and Materials Science, University of Science and Technology of China (USTC), Hefei, 230026, PR China
| | - Jun Jiang
- Hefei National Laboratory for Physical Sciences at the Microscale, School of Chemistry and Materials Science, University of Science and Technology of China (USTC), Hefei, 230026, PR China
| | - Guangming Huang
- Hefei National Laboratory for Physical Sciences at the Microscale, School of Chemistry and Materials Science, University of Science and Technology of China (USTC), Hefei, 230026, PR China
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Corona discharge electrospray ionization of formate-containing solutions enables in-source reduction of disulfide bonds. Anal Bioanal Chem 2018; 411:4729-4737. [PMID: 30397758 DOI: 10.1007/s00216-018-1447-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2018] [Revised: 10/12/2018] [Accepted: 10/22/2018] [Indexed: 01/05/2023]
Abstract
Disulfide bonds are critical linkages for maintaining protein structure and enzyme activity. These linkages, however, can limit peptide sequencing efforts by mass spectrometry (MS) and often require chemical reduction and alkylation. Under such conditions, information regarding cysteine connectivity is lost. Online partial disulfide reduction within the electrospray (ESI) source has recently been established as a means to identify complex cysteine linkage patterns in a liquid chromatography-MS experiment without the need for sample pre-treatment. Corona discharge (CD) is invoked as the causative factor of this in-source reduction (ISR); however, evidence remains largely circumstantial. In this study, we demonstrate that instrumental factors-nebulizing gas, ESI capillary material, organic solvent content, ESI spray needle-to-MS distance-all modulate the degree of reduction observed for the single disulfide in oxytocin, further implicating CD in ISR. Rigorous analysis of solution conditions, however, reveals that corona discharge alone can induce only minor disulfide reduction. We establish that CD-ESI of peptide solutions containing formic acid or its conjugate base results in a dramatic increase in disulfide reduction. It is also determined that ISR is exacerbated at low pH for complex peptides containing multiple disulfide bonds and possessing higher-order structure, as well as for a small protein. Overall, our results demonstrate that ESI of formate/formic acid-containing solutions under corona discharge conditions facilitates disulfide ISR, likely by a similar reduction pathway measured in γ-radiolysis studies nearly three decades ago.
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Li G, Zheng S, Chen Y, Hou Z, Huang G. Reliable Tracking In-Solution Protein Unfolding via Ultrafast Thermal Unfolding/Ion Mobility-Mass Spectrometry. Anal Chem 2018; 90:7997-8001. [PMID: 29894165 DOI: 10.1021/acs.analchem.8b00859] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Sequential unfolding of monomeric proteins is important for the global understanding of local conformational elements (e.g., secondary structures and domain connections) within those protein assemblies. Ion mobility-mass spectrometry (IM-MS) is an emerging and promising technique for probing gradual protein structural perturbations in the gas phase. However, it is still challenging to track sequential unfolding in the solution phase. Here, we extended IM-MS to track in-solution sequential unfolding of monomeric proteins having single and/or multidomains. The present method combines ultrafast local heating effect (LHE)-driven sequential unfolding with IM-MS identification. Protein sequential unfolding in solution is demonstrated by the rapid and controllable IM-MS data switch between native and gradually unfolded states. Our results show that LHE induces gradual protein conformational transitions associated with biological functions, where IM-MS tracks the sequential unfolding of monomeric proteins.
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Abstract
The identification of endogenous proteins as well as their binding to metal ions in living cells is determined by combining pulsed electrophoretic separations with nanoelectrospray ionization followed by mass spectrometric detection. This approach avoids problems resulting from the complicated cellular environment. In this manner, we demonstrate the rapid identification (300 ms or less) of intact proteins from living E. coli cells including the complexation of calmodulin with calcium ion. The latter showed different binding states from those observed in in vitro studies. These observations also reveal in vitro measurements do not necessarily represent the actual situation in living cells. We conclude that the attempted in situ measurement of intracellular proteins with minimal sampling processes should be preferred.
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Affiliation(s)
- Gongyu Li
- Department of Chemistry, School of Chemistry and Materials Science, University of Science and Technology of China , Hefei, Anhui 230026, P. R. China
| | - Siming Yuan
- Department of Chemistry, School of Chemistry and Materials Science, University of Science and Technology of China , Hefei, Anhui 230026, P. R. China
| | - Yang Pan
- National Synchrotron Radiation Laboratory, University of Science and Technology of China , Hefei, Anhui 230029, P. R. China
| | - Yangzhong Liu
- Department of Chemistry, School of Chemistry and Materials Science, University of Science and Technology of China , Hefei, Anhui 230026, P. R. China
| | - Guangming Huang
- Department of Chemistry, School of Chemistry and Materials Science, University of Science and Technology of China , Hefei, Anhui 230026, P. R. China
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Yin Y, Li G, Guan Y, Huang G. Sheathless interface to match flow rate of capillary electrophoresis with electrospray mass spectrometry using regular-sized capillary. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2016; 30 Suppl 1:68-72. [PMID: 27539418 DOI: 10.1002/rcm.7621] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
RATIONALE The flow rate match has been a great challenge when coupling capillary electrophoresis (CE) with electrospray ionization mass spectrometry (ESI-MS). Conventional CE-ESI-MS interfaces used liquid sheath flow, narrowed capillary or additional pressure to meet this requirement; sacrifice of either capillary inner diameter (i.d.) or separation efficiency is often inevitable. Thus, a regular-sized capillary-based sheathless interface would be attractive for flow rate match in CE-MS. METHODS The regular-sized capillary-based CE-MS interface was achieved by coupling CE with induced electrospray ionization (iESI) which was stimulated by the fact that the iESI could both achieve flow rate down to 0.2 μL/min and retain ionization efficiency. The CE-iESI-MS interface was completed with an intact separation capillary, outside the outlet end of which a metal electrode was attached for the application of alternating current (ac) high voltage (HV). RESULTS The feasibility of this CE-iESI-MS interface was demonstrated through the stable total ion chromatograms obtained by continuous CE infusion of tripropylamine with regular-sized capillaries. Tripropylamine and atenolol were separated and detected successfully in phosphate buffer solution (PBS) by CE-iESI-MS using a 50 or 75 μm i.d. capillary. Furthermore, this new interface showed a better signal-to-noise (S/N) of 3 to 7 times enhancement compared with another sheathless CE-ESI-MS interface that using one high voltage for both separation and electrospray when analyzing the mixture of tripropylamine and proline in NH4 OAc buffer. In addition, the reproducibility of this interface gave satisfactory results with relative standard deviation (RSD) in retention time in the range between 1% and 3%. CONCLUSIONS The novel sheathless CE-MS interface introduced here could match conventional electroosmotic flow (EOF) with electrospray which could also preserve the separation efficiency and sensitivity of CE-MS. This newly developed CE-iESI-MS interface was also demonstrated to be effective for different buffers, PBS and NH4 OAc, without any additives such as methanol and acetic acid. Hence, we believe that this sheathless CE-MS interface could be operated with other nonvolatile and volatile buffers. Copyright © 2016 John Wiley & Sons, Ltd.
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Affiliation(s)
- Yue Yin
- Department of Chemistry, School of Chemistry and Materials Science, University of Science and Technology of China (USTC), Hefei, 230026, China
| | - Gongyu Li
- Department of Chemistry, School of Chemistry and Materials Science, University of Science and Technology of China (USTC), Hefei, 230026, China
| | - Yafeng Guan
- Department of Instrumentation and Analytical Chemistry, Key Laboratory of Separation Science for Analytical Chemistry of CAS, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, 116023, China
| | - Guangming Huang
- Department of Chemistry, School of Chemistry and Materials Science, University of Science and Technology of China (USTC), Hefei, 230026, China
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Abstract
Ambient ionization source, thermal bursting ionization (TBI), was characterized for complex liquid sample analysis with mass spectrometry.
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Affiliation(s)
- Jiying Pei
- School of Marine Sciences
- Guangxi University
- Nanning
- P. R. China
| | - Kefu Yu
- School of Marine Sciences
- Guangxi University
- Nanning
- P. R. China
| | - Yinghui Wang
- School of Marine Sciences
- Guangxi University
- Nanning
- P. R. China
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Li G, Pei J, Yin Y, Huang G. Direct sequencing of a disulfide-linked peptide with electrospray ionization tandem mass spectrometry. Analyst 2015; 140:2623-7. [DOI: 10.1039/c5an00011d] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Enhanced corona discharge was employed for in-spray dissociation of disulfide bonds, facilitating disulfide-containing peptide sequencing with ESI-MS/MS.
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Affiliation(s)
- Gongyu Li
- Department of Chemistry
- University of Science and Technology of China
- Hefei
- P. R. China
| | - Jiying Pei
- Department of Chemistry
- University of Science and Technology of China
- Hefei
- P. R. China
| | - Yue Yin
- Department of Chemistry
- University of Science and Technology of China
- Hefei
- P. R. China
| | - Guangming Huang
- Department of Chemistry
- University of Science and Technology of China
- Hefei
- P. R. China
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