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Kosheleva I, Henning R, Kim I, Kim SO, Kusel M, Srajer V. Sample-minimizing co-flow cell for time-resolved pump-probe X-ray solution scattering. JOURNAL OF SYNCHROTRON RADIATION 2023; 30:490-499. [PMID: 36891863 PMCID: PMC10000795 DOI: 10.1107/s1600577522012127] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2022] [Accepted: 12/22/2022] [Indexed: 06/10/2023]
Abstract
A fundamental problem in biological sciences is understanding how macromolecular machines work and how the structural changes of a molecule are connected to its function. Time-resolved techniques are vital in this regard and essential for understanding the structural dynamics of biomolecules. Time-resolved small- and wide-angle X-ray solution scattering has the capability to provide a multitude of information about the kinetics and global structural changes of molecules under their physiological conditions. However, standard protocols for such time-resolved measurements often require significant amounts of sample, which frequently render time-resolved measurements impossible. A cytometry-type sheath co-flow cell, developed at the BioCARS 14-ID beamline at the Advanced Photon Source, USA, allows time-resolved pump-probe X-ray solution scattering measurements to be conducted with sample consumption reduced by more than ten times compared with standard sample cells and protocols. The comparative capabilities of the standard and co-flow experimental setups were demonstrated by studying time-resolved signals in photoactive yellow protein.
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Affiliation(s)
- Irina Kosheleva
- BioCARS, Center for Advanced Radiation Sources, The University of Chicago, 9700 South Cass Ave, Bld 434B, Lemont, IL 60439, USA
| | - Robert Henning
- BioCARS, Center for Advanced Radiation Sources, The University of Chicago, 9700 South Cass Ave, Bld 434B, Lemont, IL 60439, USA
| | - Insik Kim
- BioCARS, Center for Advanced Radiation Sources, The University of Chicago, 9700 South Cass Ave, Bld 434B, Lemont, IL 60439, USA
| | - Seong Ok Kim
- Department of Chemistry, Korea Advanced Institute of Science and Technology, E6-6 #513, 291 Daehak-ro, Daejeon, Yuseong-gu 34141, Republic of Korea
| | - Michael Kusel
- Kusel Design, 12 Coghlan Street, Niddrie, Wurundjeri Country 3042, Australia
| | - Vukica Srajer
- BioCARS, Center for Advanced Radiation Sources, The University of Chicago, 9700 South Cass Ave, Bld 434B, Lemont, IL 60439, USA
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2
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A comparative study: conventional and modified serpentine micromixers. CHEMICAL PRODUCT AND PROCESS MODELING 2022. [DOI: 10.1515/cppm-2022-0022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Abstract
The study of flow and mixing dynamics for conventional micromixers as well as micromixers with split and recombine (SAR) units has been carried out using laminar and transport diluted physics modules. Initially, a pilot numerical analysis was done for the basic Y-shaped curved, rectangular and triangular serpentine micromixers. Later, SAR units have been added to these basic designs and the effect of SAR units on the performance characteristics viz., mixing index, pressure drop, performance index and pumping power has been studied. In-depth qualitative analysis was also carried out to visualize the flow and mixing dynamics for the Reynolds number in the range from 0.1–50. The study results revealed that the square shaped chambers and circular obstacle based rectangular serpentine micromixer (SCCO-RSM) demonstrated better performance as compared to the other designs. The proposed micromixer is the better candidate for microfluidics applications such as Lab-On-a-Chip (LOC), Micro-Total-Analysis-Systems (µTAS) and Point of Care Testing (POCT), etc.
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3
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Liu C, Li Y, Liu BF. Micromixers and their applications in kinetic analysis of biochemical reactions. Talanta 2019; 205:120136. [DOI: 10.1016/j.talanta.2019.120136] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2019] [Revised: 07/03/2019] [Accepted: 07/08/2019] [Indexed: 01/11/2023]
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4
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Abstract
Triosephosphate isomerase (TIM) barrel proteins have not only a conserved architecture that supports a myriad of enzymatic functions, but also a conserved folding mechanism that involves on- and off-pathway intermediates. Although experiments have proven to be invaluable in defining the folding free-energy surface, they provide only a limited understanding of the structures of the partially folded states that appear during folding. Coarse-grained simulations employing native centric models are capable of sampling the entire energy landscape of TIM barrels and offer the possibility of a molecular-level understanding of the readout from sequence to structure. We have combined sequence-sensitive native centric simulations with small-angle X-ray scattering and time-resolved Förster resonance energy transfer to monitor the formation of structure in an intermediate in the Sulfolobus solfataricus indole-3-glycerol phosphate synthase TIM barrel that appears within 50 μs and must at least partially unfold to achieve productive folding. Simulations reveal the presence of a major and 2 minor folding channels not detected in experiments. Frustration in folding, i.e., backtracking in native contacts, is observed in the major channel at the initial stage of folding, as well as late in folding in a minor channel before the appearance of the native conformation. Similarities in global and pairwise dimensions of the early intermediate, the formation of structure in the central region that spreads progressively toward each terminus, and a similar rate-limiting step in the closing of the β-barrel underscore the value of combining simulation and experiment to unravel complex folding mechanisms at the molecular level.
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5
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Abstract
This Feature Article presents a view of the protein folding transition based on the hypothesis that Nature has built features within the sequences that enable a Shortcut to efficient folding. Nature's Shortcut is proposed to be the early establishment of a set of nonlocal weak contacts, constituting protein loops that significantly constrain regions of the collapsed disordered protein into a native-like low-resolution fluctuating topology of major sections of the backbone. Nature's establishment of this scaffold of nonlocal contacts is claimed to bypass what would otherwise be a nearly hopeless unaided search for the final three-dimensional structure in proteins longer than ∼100 amino acids. To support this main contention of the Feature Article, the loop hypothesis (LH) description of early folding events is experimentally tested with time-resolved Förster resonance energy transfer techniques for adenylate kinase, and the data are shown to be consistent with theoretical predictions from the sequential collapse model (SCM). The experimentally based LH and the theoretically founded SCM are argued to provide a unified picture of the role of nonlocal contacts as constituting Nature's Shortcut to protein folding. Importantly, the SCM is shown to reliably predict key nonlocal contacts utilizing only primary sequence information. This view on Nature's Shortcut is open to the protein community for further detailed assessment, including its practical consequences, by suitable application of advanced experimental and computational techniques.
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Affiliation(s)
| | - Elisha Haas
- The Goodman Faculty of Life Sciences , Bar-Ilan University , Ramat Gan 52900 , Israel
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6
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7
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Tuukkanen AT, Spilotros A, Svergun DI. Progress in small-angle scattering from biological solutions at high-brilliance synchrotrons. IUCRJ 2017; 4:518-528. [PMID: 28989709 PMCID: PMC5619845 DOI: 10.1107/s2052252517008740] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2017] [Accepted: 06/12/2017] [Indexed: 05/26/2023]
Abstract
Small-angle X-ray scattering (SAXS) is an established technique that provides low-resolution structural information on macromolecular solutions. Recent decades have witnessed significant progress in both experimental facilities and in novel data-analysis approaches, making SAXS a mainstream method for structural biology. The technique is routinely applied to directly reconstruct low-resolution shapes of proteins and to generate atomistic models of macromolecular assemblies using hybrid approaches. Very importantly, SAXS is capable of yielding structural information on systems with size and conformational polydispersity, including highly flexible objects. In addition, utilizing high-flux synchrotron facilities, time-resolved SAXS allows analysis of kinetic processes over time ranges from microseconds to hours. Dedicated bioSAXS beamlines now offer fully automated data-collection and analysis pipelines, where analysis and modelling is conducted on the fly. This enables SAXS to be employed as a high-throughput method to rapidly screen various sample conditions and additives. The growing SAXS user community is supported by developments in data and model archiving and quality criteria. This review illustrates the latest developments in SAXS, in particular highlighting time-resolved applications aimed at flexible and evolving systems.
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Affiliation(s)
- Anne T. Tuukkanen
- European Molecular Biology Laboratory, EMBL Hamburg c/o DESY, Notkestrasse 85, 22607 Hamburg, Germany
| | - Alessandro Spilotros
- European Molecular Biology Laboratory, EMBL Hamburg c/o DESY, Notkestrasse 85, 22607 Hamburg, Germany
| | - Dmitri I. Svergun
- European Molecular Biology Laboratory, EMBL Hamburg c/o DESY, Notkestrasse 85, 22607 Hamburg, Germany
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8
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Bingaman JL, Messina KJ, Bevilacqua PC. Probing fast ribozyme reactions under biological conditions with rapid quench-flow kinetics. Methods 2017; 120:125-134. [PMID: 28315484 DOI: 10.1016/j.ymeth.2017.03.011] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2016] [Revised: 02/28/2017] [Accepted: 03/10/2017] [Indexed: 11/24/2022] Open
Abstract
Reaction kinetics on the millisecond timescale pervade the protein and RNA fields. To study such reactions, investigators often perturb the system with abiological solution conditions or substrates in order to slow the rate to timescales accessible by hand mixing; however, such perturbations can change the rate-limiting step and obscure key folding and chemical steps that are found under biological conditions. Mechanical methods for collecting data on the millisecond timescale, which allow these perturbations to be avoided, have been developed over the last few decades. These methods are relatively simple and can be conducted on affordable and commercially available instruments. Here, we focus on using the rapid quench-flow technique to study the fast reaction kinetics of RNA enzymes, or ribozymes, which often react on the millisecond timescale under biological conditions. Rapid quench of ribozymes is completely parallel to the familiar hand-mixing approach, including the use of radiolabeled RNAs and fractionation of reactions on polyacrylamide gels. We provide tips on addressing and preventing common problems that can arise with the rapid-quench technique. Guidance is also offered on ensuring the ribozyme is properly folded and fast-reacting. We hope that this article will facilitate the broader use of rapid-quench instrumentation to study fast-reacting ribozymes under biological reaction conditions.
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Affiliation(s)
- Jamie L Bingaman
- Department of Chemistry and Center for RNA Molecular Biology, The Pennsylvania State University, University Park, PA 16802, United States.
| | - Kyle J Messina
- Department of Chemistry and Center for RNA Molecular Biology, The Pennsylvania State University, University Park, PA 16802, United States
| | - Philip C Bevilacqua
- Department of Chemistry and Center for RNA Molecular Biology, The Pennsylvania State University, University Park, PA 16802, United States; Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA 16802, United States.
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9
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Ghazal A, Lafleur JP, Mortensen K, Kutter JP, Arleth L, Jensen GV. Recent advances in X-ray compatible microfluidics for applications in soft materials and life sciences. LAB ON A CHIP 2016; 16:4263-4295. [PMID: 27731448 DOI: 10.1039/c6lc00888g] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
The increasingly narrow and brilliant beams at X-ray facilities reduce the requirements for both sample volume and data acquisition time. This creates new possibilities for the types and number of sample conditions that can be examined but simultaneously increases the demands in terms of sample preparation. Microfluidic-based sample preparation techniques have emerged as elegant alternatives that can be integrated directly into the experimental X-ray setup remedying several shortcomings of more traditional methods. We review the use of microfluidic devices in conjunction with X-ray measurements at synchrotron facilities in the context of 1) mapping large parameter spaces, 2) performing time resolved studies of mixing-induced kinetics, and 3) manipulating/processing samples in ways which are more demanding or not accessible on the macroscale. The review covers the past 15 years and focuses on applications where synchrotron data collection is performed in situ, i.e. directly on the microfluidic platform or on a sample jet from the microfluidic device. Considerations such as the choice of materials and microfluidic designs are addressed. The combination of microfluidic devices and measurements at large scale X-ray facilities is still emerging and far from mature, but it definitely offers an exciting array of new possibilities.
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Affiliation(s)
- Aghiad Ghazal
- Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen, Denmark.
| | - Josiane P Lafleur
- Dept. of Pharmacy, University of Copenhagen, Universitetsparken 2, DK-2100 Copenhagen, Denmark
| | - Kell Mortensen
- Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen, Denmark.
| | - Jörg P Kutter
- Dept. of Pharmacy, University of Copenhagen, Universitetsparken 2, DK-2100 Copenhagen, Denmark
| | - Lise Arleth
- Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen, Denmark.
| | - Grethe V Jensen
- Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen, Denmark.
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10
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11
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Goluguri RR, Udgaonkar JB. Microsecond Rearrangements of Hydrophobic Clusters in an Initially Collapsed Globule Prime Structure Formation during the Folding of a Small Protein. J Mol Biol 2016; 428:3102-17. [PMID: 27370109 DOI: 10.1016/j.jmb.2016.06.015] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2016] [Revised: 06/17/2016] [Accepted: 06/19/2016] [Indexed: 12/14/2022]
Abstract
Determining how polypeptide chain collapse initiates structure formation during protein folding is a long standing goal. It has been challenging to characterize experimentally the dynamics of the polypeptide chain, which lead to the formation of a compact kinetic molten globule (MG) in about a millisecond. In this study, the sub-millisecond events that occur early during the folding of monellin from the guanidine hydrochloride-unfolded state have been characterized using multiple fluorescence and fluorescence resonance energy transfer probes. The kinetic MG is shown to form in a noncooperative manner from the unfolded (U) state as a result of at least three different processes happening during the first millisecond of folding. Initial chain compaction completes within the first 37μs, and further compaction occurs only after structure formation commences at a few milliseconds of folding. The transient nonnative and native-like hydrophobic clusters with side chains of certain residues buried form during the initial chain collapse and the nonnative clusters quickly disassemble. Subsequently, partial chain desolvation occurs, leading to the formation of a kinetic MG. The initial chain compaction and subsequent chain rearrangement appear to be barrierless processes. The two structural rearrangements within the collapsed globule appear to prime the protein for the actual folding transition.
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Affiliation(s)
- Rama Reddy Goluguri
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bengaluru 560065, India
| | - Jayant B Udgaonkar
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bengaluru 560065, India.
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12
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Mortensen DN, Williams ER. Ultrafast (1 μs) Mixing and Fast Protein Folding in Nanodrops Monitored by Mass Spectrometry. J Am Chem Soc 2016; 138:3453-60. [PMID: 26902747 DOI: 10.1021/jacs.5b13081] [Citation(s) in RCA: 66] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The use of theta-glass emitters and mass spectrometry to monitor reactions that occur as fast as one μs is demonstrated. Acidified aqueous solutions containing unfolded proteins are mixed with aqueous ammonium acetate solutions to increase the solution pH and induce protein folding during nanoelectrospray ionization. Protein charge-state distributions show the extent to which folding occurs, and reaction times are obtained from known protein folding time constants. Shorter reaction times are obtained by decreasing the solution flow rate, and reaction times between 1.0 and 22 μs are obtained using flow rates between 48 and 2880 pL/s, respectively. Remarkably similar reaction times are obtained for three different proteins (Trp-cage, myoglobin, and cytochrome c) with folding time constants that differ by more than an order of magnitude (4.1, 7, and 57 μs, respectively), indicating that the reaction times obtained using rapid mixing from theta-glass emitters are independent of protein identity. A folding time constant of 2.2 μs is obtained for the formation of a β-hairpin structure of renin substrate tetradecapeptide, which is the fastest folding event measured using a rapid mixing technique. The 1.0 μs reaction time obtained here is about an order of magnitude lower than the shortest reaction time probed using a conventional mixer (8 μs). Moreover, this fast reaction time is obtained with a 48 pL/s flow rate, which is 2000-times less than the flow rate required to obtained the 8 μs reaction time using a conventional mixer. These results indicate that rapid mixing with theta-glass emitters can be used to access significantly faster reaction times while consuming substantially less sample than in conventional mixing apparatus.
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Affiliation(s)
- Daniel N Mortensen
- Department of Chemistry, University of California , Berkeley, California 94720-1460, United States
| | - Evan R Williams
- Department of Chemistry, University of California , Berkeley, California 94720-1460, United States
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13
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Quérard J, Le Saux T, Gautier A, Alcor D, Croquette V, Lemarchand A, Gosse C, Jullien L. Kinetics of Reactive Modules Adds Discriminative Dimensions for Selective Cell Imaging. Chemphyschem 2016; 17:1396-413. [PMID: 26833808 DOI: 10.1002/cphc.201500987] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2015] [Indexed: 11/07/2022]
Abstract
Living cells are chemical mixtures of exceptional interest and significance, whose investigation requires the development of powerful analytical tools fulfilling the demanding constraints resulting from their singular features. In particular, multiplexed observation of a large number of molecular targets with high spatiotemporal resolution appears highly desirable. One attractive road to address this analytical challenge relies on engaging the targets in reactions and exploiting the rich kinetic signature of the resulting reactive module, which originates from its topology and its rate constants. This review explores the various facets of this promising strategy. We first emphasize the singularity of the content of a living cell as a chemical mixture and suggest that its multiplexed observation is significant and timely. Then, we show that exploiting the kinetics of analytical processes is relevant to selectively detect a given analyte: upon perturbing the system, the kinetic window associated to response read-out has to be matched with that of the targeted reactive module. Eventually, we introduce the state-of-the-art of cell imaging exploiting protocols based on reaction kinetics and draw some promising perspectives.
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Affiliation(s)
- Jérôme Quérard
- Ecole Normale Supérieure-PSL Research University; Département de Chimie; 24, rue Lhomond F-75005 Paris France
- Sorbonne Universités; UPMC Univ Paris 06, PASTEUR; F-75005 Paris France
- CNRS, UMR 8640 PASTEUR; F-75005 Paris France
| | - Thomas Le Saux
- Ecole Normale Supérieure-PSL Research University; Département de Chimie; 24, rue Lhomond F-75005 Paris France
- Sorbonne Universités; UPMC Univ Paris 06, PASTEUR; F-75005 Paris France
- CNRS, UMR 8640 PASTEUR; F-75005 Paris France
| | - Arnaud Gautier
- Ecole Normale Supérieure-PSL Research University; Département de Chimie; 24, rue Lhomond F-75005 Paris France
- Sorbonne Universités; UPMC Univ Paris 06, PASTEUR; F-75005 Paris France
- CNRS, UMR 8640 PASTEUR; F-75005 Paris France
| | - Damien Alcor
- INSERM U1065, C3M; 151 route Saint Antoine de Ginestière, BP 2 3194 F-06204 Nice Cedex 3 France
| | - Vincent Croquette
- Ecole Normale Supérieure; Département de Physique and Département de Biologie, Laboratoire de Physique Statistique UMR CNRS-ENS 8550; 24 rue Lhomond F-75005 Paris France
| | - Annie Lemarchand
- Sorbonne Universités; UPMC Univ Paris 06, Laboratoire de Physique Théorique de la Matière Condensée; 4 place Jussieu, case courrier 121 75252 Paris cedex 05 France
- CNRS, UMR 7600 LPTMC; 75005 Paris France
| | - Charlie Gosse
- Laboratoire de Photonique et de Nanostructures, LPN-CNRS; route de Nozay 91460 Marcoussis France
| | - Ludovic Jullien
- Ecole Normale Supérieure-PSL Research University; Département de Chimie; 24, rue Lhomond F-75005 Paris France
- Sorbonne Universités; UPMC Univ Paris 06, PASTEUR; F-75005 Paris France
- CNRS, UMR 8640 PASTEUR; F-75005 Paris France
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14
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Kim H, Kim S, Jung Y, Han J, Yun JH, Chang I, Lee W. Probing the Folding-Unfolding Transition of a Thermophilic Protein, MTH1880. PLoS One 2016; 11:e0145853. [PMID: 26766214 PMCID: PMC4713090 DOI: 10.1371/journal.pone.0145853] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2015] [Accepted: 12/09/2015] [Indexed: 11/18/2022] Open
Abstract
The folding mechanism of typical proteins has been studied widely, while our understanding of the origin of the high stability of thermophilic proteins is still elusive. Of particular interest is how an atypical thermophilic protein with a novel fold maintains its structure and stability under extreme conditions. Folding-unfolding transitions of MTH1880, a thermophilic protein from Methanobacterium thermoautotrophicum, induced by heat, urea, and GdnHCl, were investigated using spectroscopic techniques including circular dichorism, fluorescence, NMR combined with molecular dynamics (MD) simulations. Our results suggest that MTH1880 undergoes a two-state N to D transition and it is extremely stable against temperature and denaturants. The reversibility of refolding was confirmed by spectroscopic methods and size exclusion chromatography. We found that the hyper-stability of the thermophilic MTH1880 protein originates from an extensive network of both electrostatic and hydrophobic interactions coordinated by the central β-sheet. Spectroscopic measurements, in combination with computational simulations, have helped to clarify the thermodynamic and structural basis for hyper-stability of the novel thermophilic protein MTH1880.
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Affiliation(s)
- Heeyoun Kim
- Department of Biochemistry, College of Life Science and Biotechnology, Yonsei University, Seoul, 120–740, Korea
| | - Sangyeol Kim
- Department of Physics, Pusan National University, Busan, 609–735, Korea
- Center for Proteome Biophysics, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu, 711–873, Korea
| | - Youngjin Jung
- Department of Biochemistry, College of Life Science and Biotechnology, Yonsei University, Seoul, 120–740, Korea
| | - Jeongmin Han
- Department of Biochemistry, College of Life Science and Biotechnology, Yonsei University, Seoul, 120–740, Korea
| | - Ji-Hye Yun
- Department of Biochemistry, College of Life Science and Biotechnology, Yonsei University, Seoul, 120–740, Korea
| | - Iksoo Chang
- Center for Proteome Biophysics, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu, 711–873, Korea
- Department of Brain and Cognitive Sciences, DGIST, Daegu, 711–873, Korea
| | - Weontae Lee
- Department of Biochemistry, College of Life Science and Biotechnology, Yonsei University, Seoul, 120–740, Korea
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Closa F, Gosse C, Jullien L, Lemarchand A. Identification of two-step chemical mechanisms using small temperature oscillations and a single tagged species. J Chem Phys 2015; 142:174108. [PMID: 25956091 DOI: 10.1063/1.4919632] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
In order to identify two-step chemical mechanisms, we propose a method based on a small temperature modulation and on the analysis of the concentration oscillations of a single tagged species involved in the first step. The thermokinetic parameters of the first reaction step are first determined. Then, we build test functions that are constant only if the chemical system actually possesses some assumed two-step mechanism. Next, if the test functions plotted using experimental data are actually even, the mechanism is attributed and the obtained constant values provide the rate constants and enthalpy of reaction of the second step. The advantage of the protocol is to use the first step as a probe reaction to reveal the dynamics of the second step, which can hence be relieved of any tagging. The protocol is anticipated to apply to many mechanisms of biological relevance. As far as ligand binding is considered, our approach can address receptor conformational changes or dimerization as well as competition with or modulation by a second partner. The method can also be used to screen libraries of untagged compounds, relying on a tracer whose concentration can be spectroscopically monitored.
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Affiliation(s)
- F Closa
- Sorbonne Universités, UPMC Univ. Paris 06, Laboratoire de Physique Théorique de la Matière Condensée, 4 place Jussieu, case courrier 121, 75252 Paris Cedex 05, France
| | - C Gosse
- Laboratoire de Photonique et de Nanostructures, LPN-CNRS, route de Nozay, 91460 Marcoussis, France
| | - L Jullien
- Department of Chemistry, Ecole Normale Supérieure - PSL Research University, 24 rue Lhomond, 75005 Paris, France
| | - A Lemarchand
- Sorbonne Universités, UPMC Univ. Paris 06, Laboratoire de Physique Théorique de la Matière Condensée, 4 place Jussieu, case courrier 121, 75252 Paris Cedex 05, France
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16
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Probing Microsecond Reactions with Microfluidic Mixers and TCSPC. SPRINGER SERIES IN CHEMICAL PHYSICS 2015. [DOI: 10.1007/978-3-319-14929-5_11] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
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17
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Mortensen DN, Williams ER. Investigating protein folding and unfolding in electrospray nanodrops upon rapid mixing using theta-glass emitters. Anal Chem 2014; 87:1281-7. [PMID: 25525976 PMCID: PMC4303338 DOI: 10.1021/ac503981c] [Citation(s) in RCA: 65] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
![]()
Theta-glass emitters are used to
rapidly mix two solutions to induce
either protein folding or unfolding during nanoelectrospray (nanoESI).
Mixing acid-denatured myoglobin with an aqueous ammonium acetate solution
to increase solution pH results in protein folding during nanoESI.
A reaction time and upper limit to the droplet lifetime of 9 ±
2 μs is obtained from the relative abundance of the folded conformer
in these rapid mixing experiments compared to that obtained from solutions
at equilibrium and a folding time constant of 7 μs. Heme reincorporation
does not occur, consistent with the short droplet lifetime and the
much longer time constant for this process. Similar mixing experiments
with acid-denatured cytochrome c and the resulting
folding during nanoESI indicate a reaction time of between 7 and 25
μs depending on the solution composition. The extent of unfolding
of holo-myoglobin upon rapid mixing with theta-glass emitters is less
than that reported previously (Fisher
et al. Anal. Chem.2014, 86, 4581−458824702054), a result
that is attributed to the much smaller, ∼1.5 μm, average
o.d. tips used here. These results indicate that the time frame during
which protein folding or unfolding can occur during nanoESI depends
both on the initial droplet size, which can be varied by changing
the emitter tip diameter, and on the solution composition. This study
demonstrates that protein folding or unfolding processes that occur
on the ∼10 μs time scale can be readily investigated
using rapid mixing with theta-glass emitters combined with mass spectrometry.
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Affiliation(s)
- Daniel N Mortensen
- Department of Chemistry, University of California , Berkeley, California 94720-1460, United States
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Mortensen D, Williams ER. Theta-glass capillaries in electrospray ionization: rapid mixing and short droplet lifetimes. Anal Chem 2014; 86:9315-21. [PMID: 25160559 PMCID: PMC4165459 DOI: 10.1021/ac502545r] [Citation(s) in RCA: 72] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2014] [Accepted: 08/26/2014] [Indexed: 02/06/2023]
Abstract
Double-barrel wire-in-a-capillary electrospray emitters prepared from theta-glass capillaries were used to mix solutions during the electrospray process. The relative flow rate of each barrel was continuously monitored with internal standards. The complexation reaction of 18-crown-6 and K(+), introduced from opposite barrels, reaches equilibrium during the electrospray process, suggesting that complete mixing also occurs. A simplified diffusion model suggests that mixing occurs in less than a millisecond, and contributions of turbulence, estimated from times of coalescing ballistic microdroplets, suggest that complete mixing occurs within a few microseconds. This mixing time is 2 orders of magnitude less than in any mixer previously coupled to a mass spectrometer. The reduction of 2,6-dichloroindophenol by l-ascorbic acid was performed using the theta-glass emitters and monitored using mass spectrometry. On the basis of the rate constant of this reaction in bulk solution, an apparent reaction time of 274 ± 60 μs was obtained. This reaction time is an upper limit to the droplet lifetime because the surface area to volume ratio and the concentration of reagents increase as the droplet evaporates and some product formation occurs in the Taylor cone prior to droplet formation. On the basis of increases in reaction rates measured by others in droplets compared to rates in bulk solution, the true droplet lifetime is likely 1-3 orders of magnitude less than the upper limit, i.e., between 27 μs and 270 ns. The rapid mixing and short droplet lifetime achieved in these experiments should enable the monitoring of many different fast reactions using mass spectrometry.
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Affiliation(s)
- Daniel
N. Mortensen
- Department
of Chemistry, University of California, Berkeley, California 94720-1460, United States
| | - Evan R. Williams
- Department
of Chemistry, University of California, Berkeley, California 94720-1460, United States
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Kirby NM, Cowieson NP. Time-resolved studies of dynamic biomolecules using small angle X-ray scattering. Curr Opin Struct Biol 2014; 28:41-6. [PMID: 25108308 DOI: 10.1016/j.sbi.2014.07.007] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2014] [Revised: 07/10/2014] [Accepted: 07/18/2014] [Indexed: 12/30/2022]
Abstract
Small angle X-ray scattering (SAXS) of biomacromolecules in solution has become a prominent technique in structural biology. Whilst the majority of current use is for static measurements, the field is also advancing for measurements where the sample at the beam position changes with time, using high throughput systems, chromatography, high speed mixing and pump-probe techniques in particular. Time resolved work is greatly aided by increasingly sophisticated software for acquiring and analysing data, together with developments in X-ray sources, beamline optics and detectors. The exploitation of spatial coherence is under development, with X-ray free electron lasers aiming to provide major advances in single molecule structure reconstruction and time resolution. Here we provide an overview of current developments advancing time resolved solution SAXS.
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Affiliation(s)
- Nigel M Kirby
- Australian Synchrotron, 800 Blackburn Road, Clayton, Victoria 3168, Australia.
| | - Nathan P Cowieson
- Australian Synchrotron, 800 Blackburn Road, Clayton, Victoria 3168, Australia
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20
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Li Y, Liu C, Feng X, Xu Y, Liu BF. Ultrafast Microfluidic Mixer for Tracking the Early Folding Kinetics of Human Telomere G-Quadruplex. Anal Chem 2014; 86:4333-9. [DOI: 10.1021/ac500112d] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Affiliation(s)
- Ying Li
- Britton Chance Center for Biomedical Photonics at Wuhan National Laboratory for Optoelectronics − Hubei Bioinformatics & Molecular Imaging Key Laboratory, Systems Biology Theme, Department of Biomedical Engineering, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Chao Liu
- Britton Chance Center for Biomedical Photonics at Wuhan National Laboratory for Optoelectronics − Hubei Bioinformatics & Molecular Imaging Key Laboratory, Systems Biology Theme, Department of Biomedical Engineering, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Xiaojun Feng
- Britton Chance Center for Biomedical Photonics at Wuhan National Laboratory for Optoelectronics − Hubei Bioinformatics & Molecular Imaging Key Laboratory, Systems Biology Theme, Department of Biomedical Engineering, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Youzhi Xu
- Britton Chance Center for Biomedical Photonics at Wuhan National Laboratory for Optoelectronics − Hubei Bioinformatics & Molecular Imaging Key Laboratory, Systems Biology Theme, Department of Biomedical Engineering, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Bi-Feng Liu
- Britton Chance Center for Biomedical Photonics at Wuhan National Laboratory for Optoelectronics − Hubei Bioinformatics & Molecular Imaging Key Laboratory, Systems Biology Theme, Department of Biomedical Engineering, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan 430074, China
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