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Balachandran N, Grainger RA, Rob T, Liuni P, Wilson DJ, Junop MS, Berti PJ. Role of Half-of-Sites Reactivity and Inter-Subunit Communications in DAHP Synthase Catalysis and Regulation. Biochemistry 2022; 61:2229-2240. [PMID: 36197914 DOI: 10.1021/acs.biochem.2c00465] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
α-Carboxyketose synthases, including 3-deoxy-d-arabinoheptulosonate 7-phosphate synthase (DAHPS), are long-standing targets for inhibition. They are challenging targets to create tight-binding inhibitors against, and inhibitors often display half-of-sites binding and partial inhibition. Half-of-sites inhibition demonstrates the existence of inter-subunit communication in DAHPS. We used X-ray crystallography and spatially resolved hydrogen-deuterium exchange (HDX) to reveal the structural and dynamic bases for inter-subunit communication in Escherichia coli DAHPS(Phe), the isozyme that is feedback-inhibited by phenylalanine. Crystal structures of this homotetrameric (dimer-of-dimers) enzyme are invariant over 91% of its sequence. Three variable loops make up 8% of the sequence and are all involved in inter-subunit contacts across the tight-dimer interface. The structures have pseudo-twofold symmetry indicative of inter-subunit communication across the loose-dimer interface, with the diagonal subunits B and C always having the same conformation as each other, while subunits A and D are variable. Spatially resolved HDX reveals contrasting responses to ligand binding, which, in turn, affect binding of the second substrate, erythrose-4-phosphate (E4P). The N-terminal peptide, M1-E12, and the active site loop that binds E4P, F95-K105, are key parts of the communication network. Inter-subunit communication appears to have a catalytic role in all α-carboxyketose synthase families and a regulatory role in some members.
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Affiliation(s)
| | - Ryan A Grainger
- Department of Biochemistry, Molecular Biology Lab, Western University, London, Ontario N6A 5C1, Canada
| | - Tamanna Rob
- Department of Chemistry, York University, Toronto, Ontario M3J 1P3, Canada
| | - Peter Liuni
- Department of Chemistry, York University, Toronto, Ontario M3J 1P3, Canada
| | - Derek J Wilson
- Department of Chemistry, York University, Toronto, Ontario M3J 1P3, Canada
| | - Murray S Junop
- Department of Biochemistry, Molecular Biology Lab, Western University, London, Ontario N6A 5C1, Canada
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2
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Zhu S, Liuni P, Chen T, Houy C, Wilson DJ, James DA. Epitope screening using Hydrogen/Deuterium Exchange Mass Spectrometry (HDX-MS): An accelerated workflow for evaluation of lead monoclonal antibodies. Biotechnol J 2021; 17:e2100358. [PMID: 34747565 DOI: 10.1002/biot.202100358] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2021] [Revised: 11/02/2021] [Accepted: 11/03/2021] [Indexed: 11/07/2022]
Abstract
BACKGROUND Epitope mapping is an increasingly important aspect of biotherapeutic and vaccine development. Recent advances in therapeutic antibody design and production have enabled candidate mAbs to be identified at a rapidly increasing rate, resulting in a significant bottleneck in the characterization of "structural" epitopes, that are challenging to determine using existing high throughput epitope mapping tools. Here, a Hydrogen/Deuterium Exchange Mass Spectrometry (HDX-MS) epitope screening workflow was introduced that is well suited for accelerated characterization of epitopes with a common antigen. MAIN METHODS AND MAJOR RESULTS The method is demonstrated on set of six candidate mAbs targeting Pertactin (PRN). Using this approach, five of the six epitopes were unambiguously determined using two HDX mixing timepoints in 24 h total run time, which is equivalent to the instrument time required to map a single epitope using the conventional workflow. CONCLUSION An accelerated HDX-MS epitope screening workflow was developed. The "screening" workflow successfully characterized five (out of six attempted) novel epitopes on the PRN antigen; information that can be used to support vaccine antigenicity assays.
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Affiliation(s)
- Shaolong Zhu
- Analytical Sciences, Sanofi Pasteur Ltd, Toronto, Ontario, Canada
| | - Peter Liuni
- Centre for Research in Mass Spectrometry, Department of Chemistry, York University, Toronto, Ontario, Canada
| | - Tricia Chen
- Analytical Sciences, Sanofi Pasteur Ltd, Toronto, Ontario, Canada
| | - Camille Houy
- Analytical Sciences, Sanofi Pasteur Ltd, Toronto, Ontario, Canada
| | - Derek J Wilson
- Centre for Research in Mass Spectrometry, Department of Chemistry, York University, Toronto, Ontario, Canada
| | - D Andrew James
- Analytical Sciences, Sanofi Pasteur Ltd, Toronto, Ontario, Canada
- Centre for Research in Mass Spectrometry, Department of Chemistry, York University, Toronto, Ontario, Canada
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Zhu S, Liuni P, Ettorre L, Chen T, Szeto J, Carpick B, James DA, Wilson DJ. Hydrogen-Deuterium Exchange Epitope Mapping Reveals Distinct Neutralizing Mechanisms for Two Monoclonal Antibodies against Diphtheria Toxin. Biochemistry 2019; 58:646-656. [PMID: 30560647 DOI: 10.1021/acs.biochem.8b01123] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The diphtheria toxoid (DT) antigen is one of the major components in pediatric and booster combination vaccines and is known to raise a protective humoral immune response upon vaccination. However, a structurally resolved analysis of diphtheria toxin (DTx) epitopes with underlying molecular mechanisms of antibody neutralization has not yet been reported. Using hydrogen-deuterium exchange mass spectrometry (HDX-MS) and Biolayer Interferometry (BLI) assays, we have characterized two neutralizing anti-DTx monoclonal antibodies (mAbs), 2-25 and 2-18, by identifying the specific epitopes on the diphtheria toxin responsible for antibody binding. Our results show that both epitopes are conformational, and mechanistically distinct. Monoclonal antibody 2-25 binds selectively to the B-subunit (translocation and receptor domain) of DTx, blocking the heparin-binding EGF-like growth factor (HBEGF) binding site. In contrast, mAb 2-18 binds to the A-subunit (catalytic domain), partially covering the catalytic loop region that shuttles NAD during catalysis. The results are discussed in the context of antigen neutralization mechanisms and can ultimately help to reveal the underlying factors that contribute to Diptheria vaccine efficacy.
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Affiliation(s)
- Shaolong Zhu
- Process Support and Process Analytical Technologies, Analytical Sciences , Sanofi Pasteur Ltd. , Toronto , Ontario M2R 3T4 , Canada.,Chemistry Department , York University , Toronto , Ontario M3J 1P3 , Canada.,Center for Research in Mass Spectrometry, Department of Chemistry , York University , Toronto , Ontario M3J 1P3 , Canada
| | - Peter Liuni
- Process Support and Process Analytical Technologies, Analytical Sciences , Sanofi Pasteur Ltd. , Toronto , Ontario M2R 3T4 , Canada.,Chemistry Department , York University , Toronto , Ontario M3J 1P3 , Canada.,Center for Research in Mass Spectrometry, Department of Chemistry , York University , Toronto , Ontario M3J 1P3 , Canada
| | - Luciano Ettorre
- Immunology Platform, Analytical Sciences , Sanofi Pasteur Ltd. , Toronto , Ontario M2R 3T4 , Canada
| | - Tricia Chen
- Immunology Platform, Analytical Sciences , Sanofi Pasteur Ltd. , Toronto , Ontario M2R 3T4 , Canada
| | - Jason Szeto
- Immunology Platform, Analytical Sciences , Sanofi Pasteur Ltd. , Toronto , Ontario M2R 3T4 , Canada
| | - Bruce Carpick
- Process Support and Process Analytical Technologies, Analytical Sciences , Sanofi Pasteur Ltd. , Toronto , Ontario M2R 3T4 , Canada
| | - D Andrew James
- Process Support and Process Analytical Technologies, Analytical Sciences , Sanofi Pasteur Ltd. , Toronto , Ontario M2R 3T4 , Canada.,Chemistry Department , York University , Toronto , Ontario M3J 1P3 , Canada
| | - Derek J Wilson
- Chemistry Department , York University , Toronto , Ontario M3J 1P3 , Canada.,Center for Research in Mass Spectrometry, Department of Chemistry , York University , Toronto , Ontario M3J 1P3 , Canada
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Lento C, Zhu S, Brown KA, Knox R, Liuni P, Wilson DJ. Time-resolved ElectroSpray Ionization Hydrogen-deuterium Exchange Mass Spectrometry for Studying Protein Structure and Dynamics. J Vis Exp 2017. [PMID: 28448048 DOI: 10.3791/55464] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Intrinsically disordered proteins (IDPs) have long been a challenge to structural biologists due to their lack of stable secondary structure elements. Hydrogen-Deuterium Exchange (HDX) measured at rapid time scales is uniquely suited to detect structures and hydrogen bonding networks that are briefly populated, allowing for the characterization of transient conformers in native ensembles. Coupling of HDX to mass spectrometry offers several key advantages, including high sensitivity, low sample consumption and no restriction on protein size. This technique has advanced greatly in the last several decades, including the ability to monitor HDX labeling times on the millisecond time scale. In addition, by incorporating the HDX workflow onto a microfluidic platform housing an acidic protease microreactor, we are able to localize dynamic properties at the peptide level. In this study, Time-Resolved ElectroSpray Ionization Mass Spectrometry (TRESI-MS) coupled to HDX was used to provide a detailed picture of residual structure in the tau protein, as well as the conformational shifts induced upon hyperphosphorylation.
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Affiliation(s)
| | | | | | - Ruth Knox
- Department of Chemistry, York University
| | | | - Derek J Wilson
- Department of Chemistry, York University; The Centre for Research in Mass Spectrometry, York University; The Centre for Research on Biomolecular Interactions, York University;
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Balachandran N, Heimhalt M, Liuni P, To F, Wilson DJ, Junop MS, Berti PJ. Potent Inhibition of 3-Deoxy-d-arabinoheptulosonate-7-phosphate (DAHP) Synthase by DAHP Oxime, a Phosphate Group Mimic. Biochemistry 2016; 55:6617-6629. [DOI: 10.1021/acs.biochem.6b00930] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
| | | | - Peter Liuni
- 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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Donovan KA, Zhu S, Liuni P, Peng F, Kessans SA, Wilson DJ, Dobson RCJ. Conformational Dynamics and Allostery in Pyruvate Kinase. J Biol Chem 2016; 291:9244-56. [PMID: 26879751 DOI: 10.1074/jbc.m115.676270] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2015] [Indexed: 12/17/2022] Open
Abstract
Pyruvate kinase catalyzes the final step in glycolysis and is allosterically regulated to control flux through the pathway. Two models are proposed to explain how Escherichia coli pyruvate kinase type 1 is allosterically regulated: the "domain rotation model" suggests that both the domains within the monomer and the monomers within the tetramer reorient with respect to one another; the "rigid body reorientation model" proposes only a reorientation of the monomers within the tetramer causing rigidification of the active site. To test these hypotheses and elucidate the conformational and dynamic changes that drive allostery, we performed time-resolved electrospray ionization mass spectrometry coupled to hydrogen-deuterium exchange studies followed by mutagenic analysis to test the activation mechanism. Global exchange experiments, supported by thermostability studies, demonstrate that fructose 1,6-bisphosphate binding to the allosteric domain causes a shift toward a globally more dynamic ensemble of conformations. Mapping deuterium exchange to peptides within the enzyme highlight site-specific regions with altered conformational dynamics, many of which increase in conformational flexibility. Based upon these and mutagenic studies, we propose an allosteric mechanism whereby the binding of fructose 1,6-bisphosphate destabilizes an α-helix that bridges the allosteric and active site domains within the monomeric unit. This destabilizes the β-strands within the (β/α)8-barrel domain and the linked active site loops that are responsible for substrate binding. Our data are consistent with the domain rotation model but inconsistent with the rigid body reorientation model given the increased flexibility at the interdomain interface, and we can for the first time explain how fructose 1,6-bisphosphate affects the active site.
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Affiliation(s)
- Katherine A Donovan
- From the Biomolecular Interaction Centre and School of Biological Sciences, University of Canterbury, Private Bag 4800, Christchurch 8041, New Zealand
| | - Shaolong Zhu
- Department of Chemistry, York University, Toronto, Ontario M3J 1P3, Canada
| | - Peter Liuni
- Department of Chemistry, York University, Toronto, Ontario M3J 1P3, Canada
| | - Fen Peng
- Biology and Biochemistry, University of Houston, Houston, Texas 77204
| | - Sarah A Kessans
- From the Biomolecular Interaction Centre and School of Biological Sciences, University of Canterbury, Private Bag 4800, Christchurch 8041, New Zealand
| | - Derek J Wilson
- Department of Chemistry, York University, Toronto, Ontario M3J 1P3, Canada, Centre for Research in Mass Spectrometry, Department of Chemistry, York University, 4700 Keele Street, Toronto, Ontario M3J 1P3, Canada, and
| | - Renwick C J Dobson
- From the Biomolecular Interaction Centre and School of Biological Sciences, University of Canterbury, Private Bag 4800, Christchurch 8041, New Zealand, Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, 30 Flemington Road, Parkville, Victoria 3010, Australia
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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Liuni P, Romanov V, Binette MJ, Zaknoun H, Tam M, Pilon P, Hendrikse J, Wilson DJ. Unambiguous Characterization of Analytical Markers in Complex, Seized Opiate Samples Using an Enhanced Ion Mobility Trace Detector-Mass Spectrometer. Anal Chem 2014; 86:10772-9. [DOI: 10.1021/ac502676d] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Peter Liuni
- Department
of Chemistry, York University, 4700 Keele Street, Toronto, Ontario M3J 1P3, Canada
| | - Vladimir Romanov
- Smiths Detection,
Inc., 7030 Century Avenue, Mississauga, Ontario L5N 2V8, Canada
| | - Marie-Josée Binette
- Canada Border
Services Agency, 79 Bentley Avenue, Ottawa, Ontario K2E 6T7, Canada
| | - Hafid Zaknoun
- Canada Border
Services Agency, 79 Bentley Avenue, Ottawa, Ontario K2E 6T7, Canada
| | - Maggie Tam
- Canada Border
Services Agency, 79 Bentley Avenue, Ottawa, Ontario K2E 6T7, Canada
| | - Pierre Pilon
- Canada Border
Services Agency, 79 Bentley Avenue, Ottawa, Ontario K2E 6T7, Canada
| | - Jan Hendrikse
- Smiths Detection,
Inc., 7030 Century Avenue, Mississauga, Ontario L5N 2V8, Canada
| | - Derek J. Wilson
- Department
of Chemistry, York University, 4700 Keele Street, Toronto, Ontario M3J 1P3, Canada
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Abstract
SIGNIFICANCE Analytical approaches that can provide insights into the mechanistic processes underlying protein folding and dynamics are few since the target analytes-high-energy structural intermediates-are short lived and often difficult to distinguish from coexisting structures. Folding "intermediates" can be populated at equilibrium using weakly denaturing solvents, but it is not clear that these species are identical to those that are transiently populated during folding under "native" conditions. Oxidative labeling with mass spectrometric analysis is a powerful alternative for structural characterization of proteins and transient protein species based on solvent exposure at specific sites. RECENT ADVANCES Oxidative labeling is increasingly used with exceedingly short (μs) labeling pulses, both to minimize the occurrence of artifactual structural changes due to the incorporation of label and to detect short-lived species. The recent introduction of facile photolytic approaches for producing reactive oxygen species is an important technological advance that will enable more widespread adoption of the technique. CRITICAL ISSUES The most common critique of oxidative labeling data is that even with brief labeling pulses, covalent modification of the protein may cause significant artifactual structural changes. FUTURE DIRECTIONS While the oxidative labeling with the analysis by mass spectrometry is mature enough that most basic methodological issues have been addressed, a complete systematic understanding of side chain reactivity in the context of intact proteins is an avenue for future work. Specifically, there remain issues around the impact of primary sequence and side chain interactions on the reactivity of "solvent-exposed" residues. Due to its analytical power, wide range of applications, and relative ease of implementation, oxidative labeling is an increasingly important technique in the bioanalytical toolbox.
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Affiliation(s)
- Peter Liuni
- 1 Department of Chemistry, York University , Toronto, Canada
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10
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Liuni P, Wilson DJ. Understanding and optimizing electrospray ionization techniques for proteomic analysis. Expert Rev Proteomics 2014; 8:197-209. [DOI: 10.1586/epr.10.111] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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Liuni P, Olkhov-Mitsel E, Orellana A, Wilson DJ. Measuring kinetic isotope effects in enzyme reactions using time-resolved electrospray mass spectrometry. Anal Chem 2013; 85:3758-64. [PMID: 23461634 DOI: 10.1021/ac400191t] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Kinetic isotope effect (KIE) measurements are a powerful tool for studying enzyme mechanisms; they can provide insights into microscopic catalytic processes and even structural constraints for transition states. However, KIEs have not come into widespread use in enzymology, due in large part to the requirement for prohibitively cumbersome experimental procedures and daunting analytical frameworks. In this work, we introduce time-resolved electrospray ionization mass spectrometry (TRESI-MS) as a straightforward, precise, and inexpensive method for measuring KIEs. Neither radioisotopes nor large amounts of material are needed and kinetic measurements for isotopically "labeled" and "unlabeled" species are acquired simultaneously in a single "competitive" assay. The approach is demonstrated first using a relatively large isotope effect associated with yeast alcohol dehydrogenase (YADH) catalyzed oxidation of ethanol. The measured macroscopic KIE of 2.19 ± 0.05 is consistent with comparable measurements in the literature but cannot be interpreted in a way that provides insights into isotope effects in individual microscopic steps. To demonstrate the ability of TRESI-MS to directly measure intrinsic KIEs and to characterize the precision of the technique, we measure a much smaller (12)C/(13)C KIE associated specifically with presteady state acylation of chymotrypsin during hydrolysis of an ester substrate.
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Affiliation(s)
- Peter Liuni
- Department of Chemistry, York University, Toronto, ON, Canada
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12
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Liuni P, Jeganathan A, Wilson DJ. Conformer selection and intensified dynamics during catalytic turnover in chymotrypsin. Angew Chem Int Ed Engl 2012; 51:9666-9. [PMID: 22936643 DOI: 10.1002/anie.201204903] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2012] [Revised: 07/31/2012] [Indexed: 11/06/2022]
Affiliation(s)
- Peter Liuni
- Chemistry, York University, 4700 Keele St., Toronto, ON, Canada
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13
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Liuni P, Jeganathan A, Wilson DJ. Conformer Selection and Intensified Dynamics During Catalytic Turnover in Chymotrypsin. Angew Chem Int Ed Engl 2012. [DOI: 10.1002/ange.201204903] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Rob T, Liuni P, Gill PK, Zhu S, Balachandran N, Berti PJ, Wilson DJ. Measuring dynamics in weakly structured regions of proteins using microfluidics-enabled subsecond H/D exchange mass spectrometry. Anal Chem 2012; 84:3771-9. [PMID: 22458633 DOI: 10.1021/ac300365u] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
This work introduces an integrated microfluidic device for measuring rapid H/D exchange (HDX) in proteins. By monitoring backbone amide HDX on the millisecond to low second time scale, we are able to characterize conformational dynamics in weakly structured regions, such as loops and molten globule-like domains that are inaccessible in conventional HDX experiments. The device accommodates the entire MS-based HDX workflow on a single chip with residence times sufficiently small (ca. 8 s) that back-exchange is negligible (≤5%), even without cooling. Components include an adjustable position capillary mixer providing a variable-time labeling pulse, a static mixer for HDX quenching, a proteolytic microreactor for rapid protein digestion, and on-chip electrospray ionization (ESI). In the present work, we characterize device performance using three model systems, each illustrating a different application of 'time-resolved' HDX. Ubiquitin is used to illustrate a crude, high throughput structural analysis based on a single subsecond HDX time-point. In experiments using cytochrome c, we distinguish dynamic behavior in loops, establishing a link between flexibility and interactions with the heme prosthetic group. Finally, we localize an unusually high 'burst-phase' of HDX in the large tetrameric enzyme DAHP synthase to a 'molten globule-like' region surrounding the active site.
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Affiliation(s)
- Tamanna Rob
- Department of Chemistry, York University, Toronto, Ontario, Canada
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Liuni P, Rob T, Wilson DJ. A microfluidic reactor for rapid, low-pressure proteolysis with on-chip electrospray ionization. Rapid Commun Mass Spectrom 2010; 24:315-320. [PMID: 20049884 DOI: 10.1002/rcm.4391] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
A microfluidic reactor that enables rapid digestion of proteins prior to on-line analysis by electrospray ionization mass spectrometry (ESI-MS) is introduced. The device incorporates a wide (1.5 cm), shallow (10 microm) reactor 'well' that is functionalized with pepsin-agarose, a design that facilitates low-pressure operation and high clogging resistance. Electrospray ionization is carried out directly from a short metal capillary integrated into the chip outlet. Fabrication, involving laser ablation of polymethyl methacrylate (PMMA), is exceedingly straightforward and inexpensive. High sequence coverage spectra of myoglobin (Mb), ubiquitin (Ub) and bovine serum albumin (BSA) digests were obtained after <4 s of residence time in the reactor. Stress testing showed little loss of performance over approximately 2 h continuous use at high flow rates (30 microL/min). The device provides a convenient platform for a range of applications in proteomics and structural biology, i.e. to enable high-throughput workflows or to limit back-exchange in spatially resolved hydrogen/deuterium exchange (HDX) experiments.
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Affiliation(s)
- Peter Liuni
- York University Chemistry Department, Toronto, ON, M3J 1P3, Canada
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