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Kuwajima K, Yagi-Utsumi M, Yanaka S, Kato K. DMSO-Quenched H/D-Exchange 2D NMR Spectroscopy and Its Applications in Protein Science. MOLECULES (BASEL, SWITZERLAND) 2022; 27:molecules27123748. [PMID: 35744871 PMCID: PMC9230524 DOI: 10.3390/molecules27123748] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/04/2022] [Revised: 06/06/2022] [Accepted: 06/07/2022] [Indexed: 11/16/2022]
Abstract
Hydrogen/deuterium (H/D) exchange combined with two-dimensional (2D) NMR spectroscopy has been widely used for studying the structure, stability, and dynamics of proteins. When we apply the H/D-exchange method to investigate non-native states of proteins such as equilibrium and kinetic folding intermediates, H/D-exchange quenching techniques are indispensable, because the exchange reaction is usually too fast to follow by 2D NMR. In this article, we will describe the dimethylsulfoxide (DMSO)-quenched H/D-exchange method and its applications in protein science. In this method, the H/D-exchange buffer is replaced by an aprotic DMSO solution, which quenches the exchange reaction. We have improved the DMSO-quenched method by using spin desalting columns, which are used for medium exchange from the H/D-exchange buffer to the DMSO solution. This improvement has allowed us to monitor the H/D exchange of proteins at a high concentration of salts or denaturants. We describe methodological details of the improved DMSO-quenched method and present a case study using the improved method on the H/D-exchange behavior of unfolded human ubiquitin in 6 M guanidinium chloride.
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Affiliation(s)
- Kunihiro Kuwajima
- Department of Physics, School of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
- Correspondence: (K.K.); (K.K.)
| | - Maho Yagi-Utsumi
- Exploratory Research Center on Life and Living Systems and Institute for Molecular Science, National Institutes of Natural Sciences, 5-1 Higashiyama, Myodaiji, Okazaki 444-8787, Aichi, Japan; (M.Y.-U.); (S.Y.)
- Department of Functional Molecular Science, School of Physical Sciences, SOKENDAI (the Graduate University for Advanced Studies), 5-1 Higashiyama, Myodaiji, Okazaki 444-8787, Aichi, Japan
- Graduate School of Pharmaceutical Sciences, Nagoya City University, 3-1 Tanabe-dori, Mizuho-ku, Nagoya 467-8603, Aichi, Japan
| | - Saeko Yanaka
- Exploratory Research Center on Life and Living Systems and Institute for Molecular Science, National Institutes of Natural Sciences, 5-1 Higashiyama, Myodaiji, Okazaki 444-8787, Aichi, Japan; (M.Y.-U.); (S.Y.)
- Department of Functional Molecular Science, School of Physical Sciences, SOKENDAI (the Graduate University for Advanced Studies), 5-1 Higashiyama, Myodaiji, Okazaki 444-8787, Aichi, Japan
| | - Koichi Kato
- Exploratory Research Center on Life and Living Systems and Institute for Molecular Science, National Institutes of Natural Sciences, 5-1 Higashiyama, Myodaiji, Okazaki 444-8787, Aichi, Japan; (M.Y.-U.); (S.Y.)
- Department of Functional Molecular Science, School of Physical Sciences, SOKENDAI (the Graduate University for Advanced Studies), 5-1 Higashiyama, Myodaiji, Okazaki 444-8787, Aichi, Japan
- Graduate School of Pharmaceutical Sciences, Nagoya City University, 3-1 Tanabe-dori, Mizuho-ku, Nagoya 467-8603, Aichi, Japan
- Correspondence: (K.K.); (K.K.)
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Lin Y, Gross ML. Mass Spectrometry-Based Structural Proteomics for Metal Ion/Protein Binding Studies. Biomolecules 2022; 12:135. [PMID: 35053283 PMCID: PMC8773722 DOI: 10.3390/biom12010135] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Revised: 01/13/2022] [Accepted: 01/13/2022] [Indexed: 01/01/2023] Open
Abstract
Metal ions are critical for the biological and physiological functions of many proteins. Mass spectrometry (MS)-based structural proteomics is an ever-growing field that has been adopted to study protein and metal ion interactions. Native MS offers information on metal binding and its stoichiometry. Footprinting approaches coupled with MS, including hydrogen/deuterium exchange (HDX), "fast photochemical oxidation of proteins" (FPOP) and targeted amino-acid labeling, identify binding sites and regions undergoing conformational changes. MS-based titration methods, including "protein-ligand interactions by mass spectrometry, titration and HD exchange" (PLIMSTEX) and "ligand titration, fast photochemical oxidation of proteins and mass spectrometry" (LITPOMS), afford binding stoichiometry, binding affinity, and binding order. These MS-based structural proteomics approaches, their applications to answer questions regarding metal ion protein interactions, their limitations, and recent and potential improvements are discussed here. This review serves as a demonstration of the capabilities of these tools and as an introduction to wider applications to solve other questions.
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Affiliation(s)
- Yanchun Lin
- Department of Chemistry, Washington University in St. Louis, St. Louis, MO 63130, USA
| | - Michael L Gross
- Department of Chemistry, Washington University in St. Louis, St. Louis, MO 63130, USA
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Lento C, Wilson DJ. Subsecond Time-Resolved Mass Spectrometry in Dynamic Structural Biology. Chem Rev 2021; 122:7624-7646. [PMID: 34324314 DOI: 10.1021/acs.chemrev.1c00222] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Life at the molecular level is a dynamic world, where the key players-proteins, oligonucleotides, lipids, and carbohydrates-are in a perpetual state of structural flux, shifting rapidly between local minima on their conformational free energy landscapes. The techniques of classical structural biology, X-ray crystallography, structural NMR, and cryo-electron microscopy (cryo-EM), while capable of extraordinary structural resolution, are innately ill-suited to characterize biomolecules in their dynamically active states. Subsecond time-resolved mass spectrometry (MS) provides a unique window into the dynamic world of biological macromolecules, offering the capacity to directly monitor biochemical processes and conformational shifts with a structural dimension provided by the electrospray charge-state distribution, ion mobility, covalent labeling, or hydrogen-deuterium exchange. Over the past two decades, this suite of techniques has provided important insights into the inherently dynamic processes that drive function and pathogenesis in biological macromolecules, including (mis)folding, complexation, aggregation, ligand binding, and enzyme catalysis, among others. This Review provides a comprehensive account of subsecond time-resolved MS and the advances it has enabled in dynamic structural biology, with an emphasis on insights into the dynamic drivers of protein function.
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Affiliation(s)
- Cristina Lento
- Department of Chemistry, York University, Toronto, Ontario M3J 1P3, Canada
| | - Derek J Wilson
- Department of Chemistry, York University, Toronto, Ontario M3J 1P3, Canada
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McKenzie-Coe A, Shortt R, Jones LM. THE MAKING OF A FOOTPRINT IN PROTEIN FOOTPRINTING: A REVIEW IN HONOR OF MICHAEL L. GROSS. MASS SPECTROMETRY REVIEWS 2021; 40:177-200. [PMID: 32400038 PMCID: PMC7849054 DOI: 10.1002/mas.21632] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/18/2020] [Revised: 04/17/2020] [Accepted: 04/23/2020] [Indexed: 06/11/2023]
Abstract
Within the past decade protein footprinting in conjunction with mass spectrometry has become a powerful and versatile means to unravel the higher order structure of proteins. Footprinting-based approaches has demonstrated the capacity to inform on interaction sites and dynamic regions that participate in conformational changes. These findings when set in a biological perspective inform on protein folding/unfolding, protein-protein interactions, and protein-ligand interactions. In this review, we will look at the contribution of Dr. Michael L. Gross to protein footprinting approaches such as hydrogen deuterium exchange mass spectrometry and hydroxyl radical protein footprinting. This review details the development of novel footprinting methods as well as their applications to study higher order protein structure. © 2020 The Authors. Mass Spectrometry Reviews published by John Wiley & Sons Ltd. Mass Spec Rev.
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Affiliation(s)
- Alan McKenzie-Coe
- Department of Pharmaceutical Sciences, University of Maryland Baltimore, Baltimore, Maryland, 21201
| | - Raquel Shortt
- Department of Pharmaceutical Sciences, University of Maryland Baltimore, Baltimore, Maryland, 21201
| | - Lisa M Jones
- Department of Pharmaceutical Sciences, University of Maryland Baltimore, Baltimore, Maryland, 21201
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Haas P, Muralidharan M, Krogan NJ, Kaake RM, Hüttenhain R. Proteomic Approaches to Study SARS-CoV-2 Biology and COVID-19 Pathology. J Proteome Res 2021; 20:1133-1152. [PMID: 33464917 PMCID: PMC7839417 DOI: 10.1021/acs.jproteome.0c00764] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Indexed: 12/17/2022]
Abstract
The novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative agent of coronavirus disease 2019 (COVID-19), was declared a pandemic infection in March 2020. As of December 2020, two COVID-19 vaccines have been authorized for emergency use by the U.S. Food and Drug Administration, but there are no effective drugs to treat COVID-19, and pandemic mitigation efforts like physical distancing have had acute social and economic consequences. In this perspective, we discuss how the proteomic research community can leverage technologies and expertise to address the pandemic by investigating four key areas of study in SARS-CoV-2 biology. Specifically, we discuss how (1) mass spectrometry-based structural techniques can overcome limitations and complement traditional structural approaches to inform the dynamic structure of SARS-CoV-2 proteins, complexes, and virions; (2) virus-host protein-protein interaction mapping can identify the cellular machinery required for SARS-CoV-2 replication; (3) global protein abundance and post-translational modification profiling can characterize signaling pathways that are rewired during infection; and (4) proteomic technologies can aid in biomarker identification, diagnostics, and drug development in order to monitor COVID-19 pathology and investigate treatment strategies. Systems-level high-throughput capabilities of proteomic technologies can yield important insights into SARS-CoV-2 biology that are urgently needed during the pandemic, and more broadly, can inform coronavirus virology and host biology.
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Affiliation(s)
- Paige Haas
- QBI COVID-19 Research Group (QCRG), San Francisco, CA 94158, USA
- Quantitative Biosciences Institute (QBI), University of California, San Francisco, San Francisco, CA 94158, USA
- J. David Gladstone Institutes, San Francisco, CA 94158, USA
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Monita Muralidharan
- QBI COVID-19 Research Group (QCRG), San Francisco, CA 94158, USA
- Quantitative Biosciences Institute (QBI), University of California, San Francisco, San Francisco, CA 94158, USA
- J. David Gladstone Institutes, San Francisco, CA 94158, USA
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Nevan J. Krogan
- QBI COVID-19 Research Group (QCRG), San Francisco, CA 94158, USA
- Quantitative Biosciences Institute (QBI), University of California, San Francisco, San Francisco, CA 94158, USA
- J. David Gladstone Institutes, San Francisco, CA 94158, USA
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, CA 94158, USA
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Robyn M. Kaake
- QBI COVID-19 Research Group (QCRG), San Francisco, CA 94158, USA
- Quantitative Biosciences Institute (QBI), University of California, San Francisco, San Francisco, CA 94158, USA
- J. David Gladstone Institutes, San Francisco, CA 94158, USA
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Ruth Hüttenhain
- QBI COVID-19 Research Group (QCRG), San Francisco, CA 94158, USA
- Quantitative Biosciences Institute (QBI), University of California, San Francisco, San Francisco, CA 94158, USA
- J. David Gladstone Institutes, San Francisco, CA 94158, USA
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, CA 94158, USA
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Zheng S, Yuan S, Hou Z, Li G, Chen Y, Pan Y, Liu Y, Huang G. Charge-dependent modulation of specific and nonspecific protein-metal ion interactions in nanoelectrospray ionization mass spectrometry. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2019; 33:1502-1511. [PMID: 31151135 DOI: 10.1002/rcm.8493] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2019] [Revised: 05/21/2019] [Accepted: 05/22/2019] [Indexed: 06/09/2023]
Abstract
RATIONALE Previous studies found that charge state could affect both specific and nonspecific binding of protein-metal ion interactions in nanoelectrospray ionization mass spectrometry (nESI-MS). However, the two kinds of interactions have been studied individually in spite of the problem that they often coexist in the same system. Thus, it is necessary to study the effects of charge state on specific and nonspecific protein-metal ion interactions in one system to reveal more accurate binding state. METHODS The HIV-1 nucleocapsid protein (NCp7(31-55)) which can bind specifically and nonspecifically to Zn2+ served as the model to show the charge-dependent protein-metal ion interactions. Hydrogen/deuterium exchange (HDX) and photodissociation (PD) were used to demonstrate that specific binding state was correlated with protein structure. In addition to NCp7(31-55), three other model proteins were used to investigate the reason for the charge-dependent nonspecific binding. RESULTS For specific binding, we proposed that protein ions with different charge states had different conformations. The HDX results showed that labile protons in the NCp7(31-55)-Zn complex were exchanged in a charge-state-dependent way. The PD experiments revealed differential fragment yields for different charge states. For nonspecific binding, higher charge states had more Zn2+ additions, but less SO4 2- additions. The effects of charge states on nonspecific binding levels were entirely the opposite for Zn2+ and SO4 2- . These results could reveal that the nonspecific binding was caused by electrostatic interaction. CONCLUSIONS For specific binding, NCp7(31-55) with lower charge states have folding and undenatured structures. The binding states of lower charge states can better reflect more native binding states. For nonspecific binding, when multiple metal ions adduct to proteins, the proteins have more net positive charges, which tend to generate higher charge ions during electrospray.
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Affiliation(s)
- Shihui Zheng
- 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
| | - Zhuanghao Hou
- Department of Chemistry, School of Chemistry and Materials Science, University of Science and Technology of China, Hefei, Anhui, 230026, P. R. China
| | - Gongyu Li
- Department of Chemistry, School of Chemistry and Materials Science, University of Science and Technology of China, Hefei, Anhui, 230026, P. R. China
| | - Yuting Chen
- 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
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, Anhui, 230029, P. R. China
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7
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Wang H, Shu Q, Rempel DL, Frieden C, Gross ML. Continuous and pulsed hydrogen-deuterium exchange and mass spectrometry characterize CsgE oligomerization. Biochemistry 2015; 54:6475-81. [PMID: 26418947 DOI: 10.1021/acs.biochem.5b00871] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
We report the use of hydrogen-deuterium amide exchange coupled to mass spectrometry (HDX-MS) to study the interfaces of and conformational changes accompanying CsgE oligomerization. This protein plays an important role in enteric bacteria biofilm formation. Biofilms provide protection for enteric bacteria from environmental extremes and raise concerns about controlling bacteria and infectious disease. Their proteinaceous components, called curli, are extracellular functional amyloids that initiate surface contact and biofilm formation. The highly regulated curli biogenesis involves a major subunit, CsgA, a minor subunit CsgB, and a series of other accessory proteins. CsgE, possibly functioning as oligomer, is a chaperonin-like protein that delivers CsgA to an outer-membrane bound oligomeric CsgG complex. No higher-order structure, or interfaces and dynamics of its oligomerization, however, are known. In this work, we determined regions involved in CsgE self-association by continuous HDX, and, on the basis of that, prepared a double mutant W48A/F79A, derived from interface alanine scan, and verified that it exists as monomer. Using pulsed HDX and MS, we suggest there is a structural rearrangement occurring during the oligomerization of CsgE.
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Affiliation(s)
- Hanliu Wang
- Department of Chemistry, Washington University , St. Louis, Missouri 63130, United States
| | - Qin Shu
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine , St. Louis, Missouri 63110, United States
| | - Don L Rempel
- Department of Chemistry, Washington University , St. Louis, Missouri 63130, United States
| | - Carl Frieden
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine , St. Louis, Missouri 63110, United States
| | - Michael L Gross
- Department of Chemistry, Washington University , St. Louis, Missouri 63130, United States
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8
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Liuni P, Deng B, Wilson DJ. Comparing equilibrium and kinetic protein unfolding using time-resolved electrospray-coupled ion mobility mass spectrometry. Analyst 2015; 140:6973-9. [DOI: 10.1039/c5an00843c] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
We apply a new hyphenated method, TRESI-IMS-MS, to compare equilibrium and kinetic unfolding intermediates of cytochrome c.
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Affiliation(s)
- Peter Liuni
- Department of Chemistry and Centre for Research in Mass Spectrometry
- York University
- Toronto
- Canada
| | - Bin Deng
- Department of Chemistry and Centre for Research in Mass Spectrometry
- York University
- Toronto
- Canada
| | - Derek J. Wilson
- Department of Chemistry and Centre for Research in Mass Spectrometry
- York University
- Toronto
- Canada
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Nonose S, Yamashita K, Okamura T, Fukase S, Kawashima M, Sudo A, Isono H. Conformations of disulfide-intact and -reduced lysozyme ions probed by proton-transfer reactions at various temperatures. J Phys Chem B 2014; 118:9651-61. [PMID: 25046209 DOI: 10.1021/jp505621f] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Proton-transfer reactions of disulfide-intact and -reduced lysozyme ions (7+ through 14+) to 2,6-dimethylpyridine were examined in the gas phase using tandem mass spectrometry with electrospray ionization. By changing temperature of a collision cell from 280 to 460 K, temperature dependence of reaction rate constants and branching fractions was measured. Absolute reaction rate constants for the protein ions of specific charge states were determined from intensities of parent and product ions in the mass spectra. Remarkable change was observed for the rate constants and distribution of product ions. The rate constants for disulfide-intact ions changed more drastically with change of charge states and temperature than those for disulfide-reduced ions. Observed branching fractions for parent and product ions were represented by calculated reaction rate constants with a scheme of sequential process. The reaction rate constants are closely related to conformation changes with change of temperature, which are profoundly influenced by amputation of disulfide bonds.
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Affiliation(s)
- Shinji Nonose
- Graduate School of Nanobioscience, Yokohama City University , Yokohama, Japan
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10
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Teo CA, Donald WA. Solution Additives for Supercharging Proteins beyond the Theoretical Maximum Proton-Transfer Limit in Electrospray Ionization Mass Spectrometry. Anal Chem 2014; 86:4455-62. [DOI: 10.1021/ac500304r] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- Chen A. Teo
- School of Chemistry, University of New South Wales, Sydney, New South Wales 2052, Australia
| | - William A. Donald
- School of Chemistry, University of New South Wales, Sydney, New South Wales 2052, Australia
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Lemaire P, Debois D, Smargiasso N, Quinton L, Gabelica V, De Pauw EA. Use of 1,5-diaminonaphthalene to combine matrix-assisted laser desorption/ionization in-source decay fragmentation with hydrogen/deuterium exchange. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2013; 27:1837-1846. [PMID: 23857929 DOI: 10.1002/rcm.6627] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2013] [Revised: 04/12/2013] [Accepted: 05/13/2013] [Indexed: 06/02/2023]
Abstract
RATIONALE In-Source Decay (ISD) in Matrix-Assisted Laser Desorption/Ionization (MALDI) mass spectrometry is a fast and easy top-down activation method. Our objective is to find a suitable matrix to locate the deuterons following in-solution hydrogen/deuterium exchange (HDX). This matrix must circumvent the commonly encountered undesired back-exchange reactions, in order to preserve the regioselective deuteration pattern. METHODS The 1,5-diaminonaphthalene (1,5-DAN) matrix is known to be suitable for MALDI-ISD fragmentation. MALDI Mass Spectrometry Imaging (MSI) was employed to compare 1,5-DAN and other commonly used MALDI matrices with respect to the extent of back-exchange and the uniformity of the H/D exchange profiles within the MALDI spots. We tested the back-exchange on the highly sensitive amyloid-beta peptide (1-40), and proved the regioselectivity on ubiquitin and β-endorphin. RESULTS MALDI-MSI results show that 1,5-DAN leads to the least back-exchange over all the spot. MALDI-ISD fragmentation combined with H/D exchange using 1,5-DAN matrix was validated by localizing deuterons in native ubiquitin. Results agree with previous data obtained by Nuclear Magnetic Resonance (NMR) and Electron Transfer Dissociation (ETD). Moreover, 1,5-DAN matrix was used to study the H/D exchange profile of the methanol-induced helical structure of β-endorphin, and the relative protection can be explained by the polarity of residues involved in hydrogen bond formation. CONCLUSIONS We found that controlling crystallization is the most important parameter when combining H/D exchange with MALDI. The 1,5-DAN matrix is characterized by a fast crystallization kinetics, and therefore gives robust and reliable H/D exchange profiles using MALDI-ISD.
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Affiliation(s)
- Pascale Lemaire
- GIGA-R, Mass Spectrometry Laboratory, Department of Chemistry, Chemistry Building B6c, University of Liège, B-4000 Liège, Belgium
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12
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Pulsed hydrogen-deuterium exchange mass spectrometry probes conformational changes in amyloid beta (Aβ) peptide aggregation. Proc Natl Acad Sci U S A 2013; 110:14604-9. [PMID: 23959898 DOI: 10.1073/pnas.1309175110] [Citation(s) in RCA: 94] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Probing the conformational changes of amyloid beta (Aβ) peptide aggregation is challenging owing to the vast heterogeneity of the resulting soluble aggregates. To investigate the formation of these aggregates in solution, we designed an MS-based biophysical approach and applied it to the formation of soluble aggregates of the Aβ42 peptide, the proposed causative agent in Alzheimer's disease. The approach incorporates pulsed hydrogen-deuterium exchange coupled with MS analysis. The combined approach provides evidence for a self-catalyzed aggregation with a lag phase, as observed previously by fluorescence methods. Unlike those approaches, pulsed hydrogen-deuterium exchange does not require modified Aβ42 (e.g., labeling with a fluorophore). Furthermore, the approach reveals that the center region of Aβ42 is first to aggregate, followed by the C and N termini. We also found that the lag phase in the aggregation of soluble species is affected by temperature and Cu(2+) ions. This MS approach has sufficient structural resolution to allow interrogation of Aβ aggregation in physiologically relevant environments. This platform should be generally useful for investigating the aggregation of other amyloid-forming proteins and neurotoxic soluble peptide aggregates.
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13
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Resetca D, Wilson DJ. Characterizing rapid, activity-linked conformational transitions in proteins via sub-second hydrogen deuterium exchange mass spectrometry. FEBS J 2013; 280:5616-25. [DOI: 10.1111/febs.12332] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2013] [Revised: 04/26/2013] [Accepted: 05/01/2013] [Indexed: 01/01/2023]
Affiliation(s)
- Diana Resetca
- Department of Chemistry; York University; Toronto Ontario Canada
| | - Derek J. Wilson
- Department of Chemistry; York University; Toronto Ontario Canada
- Center for Research in Mass Spectrometry; Department of Chemistry; York University; Toronto Ontario Canada
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Hamdy OM, Julian RR. Reflections on charge state distributions, protein structure, and the mystical mechanism of electrospray ionization. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2012; 23:1-6. [PMID: 22076632 DOI: 10.1007/s13361-011-0284-8] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/28/2011] [Revised: 10/18/2011] [Accepted: 10/19/2011] [Indexed: 05/31/2023]
Abstract
The connection between charge state distributions, protein structure, and mechanistic details of electrospray are discussed in relation to the emerging field of gas phase structural biology. Comparisons are drawn with the established area of enzymatic catalysis in organic solvents, which shares many similar challenges. Charge solvation emerges as a dominant force in both systems that must be dealt with to enable kinetic trapping of native structures in foreign environments. Potential methods for mediating unfavorable charge solvation effects are discussed and, ironically, do not include partial solvation by water. The importance of timescale in relation to the evolution of protein structure during the process of electrospray ionization is discussed. Finally several prospects for future endeavors are highlighted.
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15
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Toews J, Rogalski JC, Kast J. Accessibility governs the relative reactivity of basic residues in formaldehyde-induced protein modifications. Anal Chim Acta 2010; 676:60-7. [DOI: 10.1016/j.aca.2010.07.040] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2010] [Revised: 07/13/2010] [Accepted: 07/27/2010] [Indexed: 11/29/2022]
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16
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Yu Z, Chen LC, Erra-Balsells R, Nonami H, Hiraoka K. Real-time reaction monitoring by probe electrospray ionization mass spectrometry. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2010; 24:1507-1513. [PMID: 20486246 DOI: 10.1002/rcm.4556] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Probe electrospray ionization (PESI) is a modified version of the electrospray ionization (ESI), where the capillary for sampling and spraying is replaced by a solid needle. High tolerance to salts and direct ambient sampling are major advantages of PESI compared with conventional ESI. In this study, PESI-MS was used to monitor some biological and chemical reactions in real-time, such as acid-induced protein denaturation, hydrogen/deuterium exchange (HDX) of peptides, and Schiff base formation. By using PESI-MS, time-resolved mass spectra and ion chromatograms can be obtained reproducibly. Real-time PESI-MS monitoring can give direct and detailed information on each chemical species taking part in reactions, and this is valuable for a better understanding of the whole reaction process and for the optimization of reaction parameters. PESI-MS can be considered as a potential tool for real-time reaction monitoring due to its simplicity in instrumental setup, direct sampling with minimum sample preparation and low sample consumption.
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Affiliation(s)
- Zhan Yu
- Clean Energy Research Center, University of Yamanashi, Kofu, Japan
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17
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Enders JR, McLean JA. Chiral and structural analysis of biomolecules using mass spectrometry and ion mobility-mass spectrometry. Chirality 2010; 21 Suppl 1:E253-64. [PMID: 19927374 DOI: 10.1002/chir.20806] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
This report describes the strategies for gas-phase chiral and structural characterization of biomolecules using mass spectrometry (MS) and ion mobility-MS (IM-MS) techniques. Because both MS and IM-MS do not directly provide chiral selectivity, methodologies for adding a chiral selector are discussed in the context of (i) host-guest (H-G) associations, (ii) diastereomeric collision-induced dissociation (CID) methods, (iii) ion-molecule reactions, and (iv) the kinetic method. MS techniques for the analysis of proteins and protein complexes are briefly described. New advances in performing rapid 2D gas-phase separations on the basis of IM-MS are reviewed with a particular emphasis on the different forms of IM instrumentation and how they are used for chiral and/or structural biomolecular studies. This report is not intended to be a comprehensive review of the field, but rather to underscore the contemporary techniques that are commonly or increasingly being used to complement measurements performed by chiroptical methodologies.
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Affiliation(s)
- Jeffrey R Enders
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee, USA
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18
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Liu J, Konermann L. Irreversible thermal denaturation of cytochrome C studied by electrospray mass spectrometry. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2009; 20:819-828. [PMID: 19200750 DOI: 10.1016/j.jasms.2008.12.016] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2008] [Revised: 12/17/2008] [Accepted: 12/18/2008] [Indexed: 05/27/2023]
Abstract
This work uses electrospray ionization mass spectrometry (ESI-MS) in conjunction with hydrogen/deuterium exchange (HDX) and optical spectroscopy for characterizing the solution-phase properties of cytochrome c (cyt c) after heat exposure. Previous work demonstrated that heating results in irreversible denaturation for a subpopulation of proteins in the sample. However, that study did not investigate the physical reasons underlying this interesting effect. Here we report that the formation of oxidative modifications at elevated temperature plays a key role for the observed behavior. Tryptic digestion followed by tandem mass spectrometry is used to identify individual oxidation sites. Trp59 and Met80 are among the modified amino acids. In native cyt c both of these residues are buried deep within the protein structure, such that covalent modifications would be expected to be particularly disruptive. ESI-MS analysis after heat exposure results in a bimodal charge-state distribution. Oxidized protein appears predominantly in charge states around 11+, whereas a considerably lower degree of oxidation is observed for the 7+ and 8+ peaks. This finding confirms that different oxidation levels are associated with different solution-phase conformations. HDX measurements for different charge states are complicated by peak distortions arising from oxygen adduction. Nonetheless, comparison with simulated peak shapes clearly shows that the HDX properties are different for high- and low-charge states, confirming that interconversion between unfolded and folded conformers is blocked in solution. In addition to oxidation, partial aggregation upon heat exposure likely contributes to the formation of irreversibly denatured protein.
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Affiliation(s)
- Jiangjiang Liu
- Department of Chemistry, The University of Western Ontario, London, Ontario, Canada
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19
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Guo N, Zhang R, Song F, He J, Xia B, Abliz Z. Characterization of acid-induced protein conformational changes and noncovalent complexes in solution by using coldspray ionization mass spectrometry. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2009; 20:845-851. [PMID: 19211263 DOI: 10.1016/j.jasms.2008.12.024] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2008] [Revised: 12/23/2008] [Accepted: 12/24/2008] [Indexed: 05/27/2023]
Abstract
Coldspray ionization (CSI) mass spectrometry, a variant of electrospray ionization (ESI) operating at low temperature (20 to -80 degrees C), has been used to characterize protein conformation and noncovalent complexes. A comparison of CSI and ESI was presented for the investigation of the equilibrium acid-induced unfolding of cytochrome c, ubiquitin, myoglobin, and cyclophilin A (CypA) over a wide range of pH values in aqueous solutions. CSI and nanoelectrospray ionization (nanoESI) were also compared in their performance to characterize the conformational changes of cytochrome c and myoglobin. Significant differences were observed, with narrower charged-state distribution and a shift to lower charge state in the CSI mass spectra compared with those in ESI and nanoESI mass spectra. The results suggest that CSI is more prone to preserving folded protein conformations in solution than the ESI and nanoESI methods. Moreover, the CSI-MS data are comparable with those obtained by other established biophysical methods, which are generally acknowledged to be the suitable techniques for monitoring protein conformation in solution. Noncovalent complexes of holomyoglobin and the protein-ligand complex between CypA and cyclosporin A (CsA) were also investigated at a neutral pH using the CSI-MS method. The results of this study suggest the ability of CSI-MS in retaining of protein conformation and noncovalent interactions in solution and probing subtle protein conformational changes. Additionally, the CSI-MS method is capable of analyzing quantitatively equilibrium unfolding transitions of proteins. CSI-MS may become one of the promising techniques for investigating protein conformation and noncovalent protein-ligand interactions in solution.
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Affiliation(s)
- Na Guo
- Key Laboratory of Bioactive Substances and Resource Utilization of Chinese Herbal Medicine, Ministry of Education, Institute of Materia Medica, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
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20
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Rob T, Wilson DJ. A versatile microfluidic chip for millisecond time-scale kinetic studies by electrospray mass spectrometry. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2009; 20:124-130. [PMID: 18845447 DOI: 10.1016/j.jasms.2008.09.005] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/02/2008] [Revised: 09/01/2008] [Accepted: 09/01/2008] [Indexed: 05/26/2023]
Abstract
An electrospray coupled microfluidic reactor for the measurement of millisecond time-scale, solution phase kinetics is introduced. The device incorporates a simple two-channel design that is etched into polymethyl methacrylate (PMMA) by laser ablation. The outlet of the device is laser cut to a sharp tip, facilitating low dead volume 'on chip' electrospray. Fabrication is fast, straightforward and highly reproducible, supporting rapid prototyping and large-scale reproduction. Device performance is characterized using a cytochrome c unfolding reaction. Unfolding processes with rates in excess of 30 s(-1) are easily measured, including the appearance of a 'native-like' intermediate that is maximally populated 180 ms post reaction initiation. To extract reliable rates from the data, a theoretical framework for the analysis of kinetics acquired under square-channel laminar flow is introduced.
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Affiliation(s)
- Tamanna Rob
- Center for Research in Mass Spectrometry, Department of Chemistry, York University, Toronto, Ontario, Canada
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21
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Konermann L, Tong X, Pan Y. Protein structure and dynamics studied by mass spectrometry: H/D exchange, hydroxyl radical labeling, and related approaches. JOURNAL OF MASS SPECTROMETRY : JMS 2008; 43:1021-1036. [PMID: 18523973 DOI: 10.1002/jms.1435] [Citation(s) in RCA: 120] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Mass spectrometry (MS) plays a central role in studies on protein structure and dynamics. This review highlights some of the recent developments in this area, with focus on applications involving the use of electrospray ionization (ESI) MS. Although this technique involves the transformation of analytes into highly nonphysiological species (desolvated gas-phase ions in the vacuum), ESI-MS can provide detailed insights into the solution-phase behavior of proteins. Notably, the ionization process itself occurs in a structurally sensitive manner. An increased degree of solution-phase unfolding is correlated with a higher level of protonation. Also, ESI allows the transfer of intact noncovalent complexes into the gas phase, thereby yielding information on binding partners, stoichiometries, and even affinities. A particular focus of this article is the use of hydrogen/deuterium exchange (HDX) methods and hydroxyl radical (.OH) labeling for monitoring dynamic and structural aspect of solution-phase proteins. Conceptual similarities and differences between the two methods are discussed. We describe a simple method for the computational simulation of protein HDX patterns, a tool that can be helpful for the interpretation of isotope exchange data recorded under mixed EX1/EX2 conditions. Important aspects of .OH labeling include a striking dependence on protein concentration, and the tendency of commonly used solvent additives to act as highly effective radical scavengers. If not properly controlled, both of these factors may lead to experimental artifacts.
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Affiliation(s)
- Lars Konermann
- Department of Chemistry, The University of Western Ontario, London, Ontario, Canada.
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22
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Ly T, Liu Z, Pujanauski BG, Sarpong R, Julian RR. Surveying Ubiquitin Structure by Noncovalent Attachment of Distance Constrained Bis(crown) Ethers. Anal Chem 2008; 80:5059-64. [DOI: 10.1021/ac800177s] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Tony Ly
- Department of Chemistry, University of California, Riverside, California 92521, and College of Chemistry, University of California, Berkeley, California 94720
| | - Zhenjiu Liu
- Department of Chemistry, University of California, Riverside, California 92521, and College of Chemistry, University of California, Berkeley, California 94720
| | - Brian G. Pujanauski
- Department of Chemistry, University of California, Riverside, California 92521, and College of Chemistry, University of California, Berkeley, California 94720
| | - Richmond Sarpong
- Department of Chemistry, University of California, Riverside, California 92521, and College of Chemistry, University of California, Berkeley, California 94720
| | - Ryan R. Julian
- Department of Chemistry, University of California, Riverside, California 92521, and College of Chemistry, University of California, Berkeley, California 94720
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23
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Suchanova B, Tuma R. Folding and assembly of large macromolecular complexes monitored by hydrogen-deuterium exchange and mass spectrometry. Microb Cell Fact 2008; 7:12. [PMID: 18394161 PMCID: PMC2365927 DOI: 10.1186/1475-2859-7-12] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2008] [Accepted: 04/04/2008] [Indexed: 11/26/2022] Open
Abstract
Recent advances in protein mass spectrometry (MS) have enabled determinations of hydrogen deuterium exchange (HDX) in large macromolecular complexes. HDX-MS became a valuable tool to follow protein folding, assembly and aggregation. The methodology has a wide range of applications in biotechnology ranging from quality control for over-expressed proteins and their complexes to screening of potential ligands and inhibitors. This review provides an introduction to protein folding and assembly followed by the principles of HDX and MS detection, and concludes with selected examples of applications that might be of interest to the biotechnology community.
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24
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Konermann L, Messinger J, Hillier W. Mass Spectrometry-Based Methods for Studying Kinetics and Dynamics in Biological Systems. BIOPHYSICAL TECHNIQUES IN PHOTOSYNTHESIS 2008. [DOI: 10.1007/978-1-4020-8250-4_9] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
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25
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Abzalimov RR, Kaltashov IA. Extraction of local hydrogen exchange data from HDX CAD MS measurements by deconvolution of isotopic distributions of fragment ions. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2006; 17:1543-1551. [PMID: 16934998 DOI: 10.1016/j.jasms.2006.07.017] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2006] [Revised: 07/18/2006] [Accepted: 07/19/2006] [Indexed: 05/11/2023]
Abstract
Hydrogen/deuterium exchange (HDX) coupled to protein fragmentation either in solution (by means of proteolysis) or in the gas phase (using collisional activation of protein ions) and followed by mass spectral measurements of deuterium content of individual fragments has become one of the major experimental tools to probe protein structure and dynamics. One difficulty, which often arises in the course of interpretation of HDX MS data, is a need to separate deuterium contribution to the observed isotopic patterns from that of naturally occurring isotopes. Another frequently encountered problem, especially when HDX in solution is followed by protein ion fragmentation in the gas phase, is a need to determine the deuterium content of an internal protein segment based on the measured isotopic distributions of overlapping fragments. While several algorithms were developed in the past several years to address the first problem, the second one did not enjoy as much attention. Here we report a new algorithm based on a maximum entropy principle, which is capable of extracting local exchange data form the isotope distribution of overlapping fragments, as well as subtracting the background due to the presence of natural isotopes and residual deuterium in exchange buffers. The new method is tested with several proteins and appears to generate stable solutions even under unfavorable circumstances, e.g., when the resolving power of a mass analyzer is not sufficient to avoid signal interference or when the isotopic distributions of individual fragments are complex and cannot be approximated with simple binomial distributions. The latter feature makes the algorithm particularly useful when the exchange in solution is correlated or semicorrelated, paving the way to precise structural characterization of non-native protein states in solution.
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Affiliation(s)
- Rinat R Abzalimov
- Department of Chemistry, University of Massachusetts-Amherst, 710 North Pleasant Street, 01003, Amherst, MA, USA
| | - Igor A Kaltashov
- Department of Chemistry, University of Massachusetts-Amherst, 710 North Pleasant Street, 01003, Amherst, MA, USA.
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26
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Koeniger SL, Merenbloom SI, Sevugarajan S, Clemmer DE. Transfer of structural elements from compact to extended states in unsolvated ubiquitin. J Am Chem Soc 2006; 128:11713-9. [PMID: 16939296 PMCID: PMC2507767 DOI: 10.1021/ja062137g] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Multidimensional ion mobility spectrometry techniques (IMS-IMS and IMS-IMS-IMS) combined with mass spectrometry are used to study structural transitions of ubiquitin ions in the gas phase. It is possible to select and activate narrow distributions of compact and partially folded conformation types and examine new distributions of structures that are formed. Different compact conformations unfold, producing a range of new partially folded states and three resolvable peaks associated with elongated conformers. Under gentle activation conditions, the final populations of the three elongated forms depend on the initial structures of the selected ions. This requires that some memory of the compact state (most likely secondary structure) is preserved along the unfolding pathway. Activation of selected, partially folded intermediates (formed from specific compact states) leads to elongated state populations that are consistent with the initial selected compact form-evidence that intermediates not only retain elements of initial structure but also are capable of transmitting structure to final states.
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Affiliation(s)
- Stormy L Koeniger
- Department of Chemistry, Indiana University, Bloomington, Indiana 47405, USA
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27
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Ly T, Julian RR. Using ESI-MS to probe protein structure by site-specific noncovalent attachment of 18-crown-6. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2006; 17:1209-15. [PMID: 16766206 DOI: 10.1016/j.jasms.2006.05.007] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2006] [Revised: 05/15/2006] [Accepted: 05/17/2006] [Indexed: 05/10/2023]
Abstract
A new method for probing the equilibrium structures and folding states of proteins utilizing electrospray ionization mass spectrometry is described. Protein structure is explored as a function of side-chain availability as determined by a specific interaction between lysine and 18-crown-6 ether (18C6). Various intramolecular interactions are competitive with the lysine/18C6 interaction and can prevent noncovalent attachment of 18C6. Changes to protein structure modify these inhibiting intramolecular interactions, which leads to a change in the number of 18C6s that attach to the protein. Experiments conducted with cytochrome c, ubiquitin, and melittin reveal that the method is sensitive to changes in both tertiary and secondary structure. In addition, the structure of each charge state can be examined independently. Experiments can be performed under conditions where the pH and amount of organic cosolvent are varied. Control experiments conducted with pentalysine, which lacks structural organization, are also presented.
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Affiliation(s)
- Tony Ly
- Department of Chemistry, University of California, Riverside, California, USA
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28
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Yang F, Zhang M, Chen J, Liang Y. Structural changes of α-lactalbumin induced by low pH and oleic acid. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2006; 1764:1389-96. [PMID: 16920042 DOI: 10.1016/j.bbapap.2006.06.012] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2006] [Revised: 06/13/2006] [Accepted: 06/27/2006] [Indexed: 11/28/2022]
Abstract
The effects of low pH and oleic acid on conformation and association state of Ca2+-depleted bovine alpha-lactalbumin (apo-BLA) have been studied by electrospray ionization mass spectrometry, fluorescence spectroscopy, and circular dichroism. The experimental results demonstrate that two structurally distinct species exist in the conformational transition of apo-BLA induced by low pH. One species populates at pH 3.0 characterized as a monomeric molten globule state and the other accumulates at pH 4.0-4.5 which is a partially folded dimer. Oleic acid promotes the formation of the dimeric intermediate at pH 4.0 and 7.0, but increases the content of molten globule state remarkably at pH 3.0 compared with that in the absence of oleic acid, indicating that oleic acid at pH 3.0 plays a different role from those at pH 4.0 and 7.0. Our data provide insight into the mechanism of pH-dependent and oleic acid-dependent structural changes and oligomerization of alpha-lactalbumin, and will be helpful to the understanding of the apoptosis-inducing function of multimeric alpha-lactalbumin in which oleic acid is a necessary cofactor.
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Affiliation(s)
- Fang Yang
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan 430072, China
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29
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Abstract
For the past twenty years, the small, 76-residue protein ubiquitin has been used as a model system to study protein structure, stability, folding and dynamics. In this time, ubiquitin has become a paradigm for both the experimental and computational folding communities. The folding energy landscape is now uniquely characterised with a plethora of information available on not only the native and denatured states, but partially structured states, alternatively folded states and locally unfolded states, in addition to the transition state ensemble. This Perspective focuses on the experimental characterisation of ubiquitin using a comprehensive range of biophysical techniques.
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Affiliation(s)
- Sophie E Jackson
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, UK CB2 1EW.
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30
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Konermann L, Pan J, Wilson DJ. Protein Folding Mechanisms Studied by Time-Resolved Electrospray Mass Spectrometry. Biotechniques 2006; 40:135, 137, 139 passim. [PMID: 16526400 DOI: 10.2144/06402te01] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Affiliation(s)
- Lars Konermann
- Department of Chemistry, The University of WesternOntario, London, ON, Canada
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31
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Hoerner JK, Xiao H, Kaltashov IA. Structural and dynamic characteristics of a partially folded state of ubiquitin revealed by hydrogen exchange mass spectrometry. Biochemistry 2005; 44:11286-94. [PMID: 16101313 PMCID: PMC1473987 DOI: 10.1021/bi0509548] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Structural and dynamic properties of a partially folded conformation (A-state) of ubiquitin are studied using amide hydrogen exchange in solution (HDX) and mass spectrometric detection. A clear distinction between the native state of the protein and the A-state can be made when HDX is carried out in a semicorrelated regime. Convoluted exchange patterns are interpreted with the aid of HDX simulations in a three-state system (highly structured, partially unstructured, and fully unstructured states). The data clearly indicate a highly dynamic character of the non-native state. Furthermore, combination of HDX and protein ion fragmentation in the gas phase [by means of collision-induced dissociation (CAD)] is used to evaluate the conformational stability of various protein segments specifically in the molten globular state. Chain flexibility appears to be distributed very unevenly in this non-native conformation. The highest degree of structural disorder is displayed by the C-terminal segment (Gly(53)-Gly(76)), which was previously suggested to form a transient alpha-helix. The least dynamic segment of ubiquitin in the A-state is Thr(9)-Glu(18) (which was previously suggested to form a stable nativelike beta-strand), with the adjacent segments exhibiting somewhat diminished conformational stability. The study also demonstrates the power of mass spectrometry as a tool in providing conformer-specific information about the structure and dynamics of both native and non-native protein states coexisting in solution under equilibrium.
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Affiliation(s)
- Joshua K Hoerner
- Department of Chemistry, University of Massachusetts, Amherst, Massachusetts 01003, USA
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