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Paul B, Furst EM, Lenhoff AM, Wagner NJ, Teixeira SCM. Combined Effects of Pressure and Ionic Strength on Protein-Protein Interactions: An Empirical Approach. Biomacromolecules 2024; 25:338-348. [PMID: 38117685 DOI: 10.1021/acs.biomac.3c01001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2023]
Abstract
Proteins are exposed to hydrostatic pressure (HP) in a variety of ecosystems as well as in processing steps such as freeze-thaw, cell disruption, sterilization, and homogenization, yet pressure effects on protein-protein interactions (PPIs) remain underexplored. With the goal of contributing toward the expanded use of HP as a fundamental control parameter in protein research, processing, and engineering, small-angle X-ray scattering was used to examine the effects of HP and ionic strength on ovalbumin, a model protein. Based on an extensive data set, we develop an empirical method for scaling PPIs to a master curve by combining HP and osmotic effects. We define an effective pressure parameter that has been shown to successfully apply to other model protein data available in the literature, with deviations evident for proteins that do not follow the apparent Hofmeister series. The limitations of the empirical scaling are discussed in the context of the hypothesized underlying mechanisms.
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Affiliation(s)
- Brian Paul
- Center for Neutron Science, Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, Delaware 19716, United States
- NIST Center for Neutron Research, National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, Maryland 20899, United States
| | - Eric M Furst
- Center for Neutron Science, Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, Delaware 19716, United States
| | - Abraham M Lenhoff
- Center for Neutron Science, Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, Delaware 19716, United States
| | - Norman J Wagner
- Center for Neutron Science, Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, Delaware 19716, United States
| | - Susana C M Teixeira
- Center for Neutron Science, Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, Delaware 19716, United States
- NIST Center for Neutron Research, National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, Maryland 20899, United States
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2
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Wang J, Koduru T, Harish B, McCallum SA, Larsen KP, Patel KS, Peters EV, Gillilan RE, Puglisi EV, Puglisi JD, Makhatadze G, Royer CA. Pressure pushes tRNA Lys3 into excited conformational states. Proc Natl Acad Sci U S A 2023; 120:e2215556120. [PMID: 37339210 PMCID: PMC10293818 DOI: 10.1073/pnas.2215556120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2022] [Accepted: 05/16/2023] [Indexed: 06/22/2023] Open
Abstract
Conformational dynamics play essential roles in RNA function. However, detailed structural characterization of excited states of RNA remains challenging. Here, we apply high hydrostatic pressure (HP) to populate excited conformational states of tRNALys3, and structurally characterize them using a combination of HP 2D-NMR, HP-SAXS (HP-small-angle X-ray scattering), and computational modeling. HP-NMR revealed that pressure disrupts the interactions of the imino protons of the uridine and guanosine U-A and G-C base pairs of tRNALys3. HP-SAXS profiles showed a change in shape, but no change in overall extension of the transfer RNA (tRNA) at HP. Configurations extracted from computational ensemble modeling of HP-SAXS profiles were consistent with the NMR results, exhibiting significant disruptions to the acceptor stem, the anticodon stem, and the D-stem regions at HP. We propose that initiation of reverse transcription of HIV RNA could make use of one or more of these excited states.
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Affiliation(s)
- Jinqiu Wang
- Graduate Program in Biochemistry and Biophysics, Rensselaer Polytechnic Institute, Troy, NY12180
| | - Tejaswi Koduru
- Department of Biological Sciences, Rensselaer Polytechnic Institute, Troy, NY12180
| | | | - Scott A. McCallum
- Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, NY12180
| | - Kevin P. Larsen
- Department of Structural Biology, Stanford University School of Medicine, Stanford, CA94305
| | - Karishma S. Patel
- Department of Structural Biology, Stanford University School of Medicine, Stanford, CA94305
| | - Edgar V. Peters
- Department of Chemistry and Chemical Biology, Rensselaer Polytechnic Institute, Troy, NY12180
| | | | - Elisabetta V. Puglisi
- Department of Structural Biology, Stanford University School of Medicine, Stanford, CA94305
| | - Joseph D. Puglisi
- Department of Structural Biology, Stanford University School of Medicine, Stanford, CA94305
| | - George Makhatadze
- Department of Biological Sciences, Rensselaer Polytechnic Institute, Troy, NY12180
| | - Catherine A. Royer
- Department of Biological Sciences, Rensselaer Polytechnic Institute, Troy, NY12180
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3
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Shkolnikov Lozober H, Okun Z, Parvari G, Shpigelman A. The Effect of Storage and Pasteurization (Thermal and High-Pressure) Conditions on the Stability of Phycocyanobilin and Phycobiliproteins. Antioxidants (Basel) 2023; 12:antiox12030568. [PMID: 36978816 PMCID: PMC10045346 DOI: 10.3390/antiox12030568] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2023] [Revised: 02/20/2023] [Accepted: 02/21/2023] [Indexed: 03/02/2023] Open
Abstract
The utilization of natural blue pigments in foods is difficult as they are usually unstable during processing and the commonly applied pH. The current study focuses on natural blue pigment, possessing antioxidant properties, found in Arthrospira platensis (spirulina), and phycobiliproteins (PBP). These pigments are a complex of conjugated protein and non-protein components, known as phycocyanobilin. PBP has low stability during pasteurization (high-pressure or heat treatments), resulting in protein denaturation and color deterioration that limits the application. The phycocyanobilin pigment might also be liable to oxidation during pasteurization and storage, resulting in color deterioration. Yet, the instability of the pigment phycocyanobilin during the pasteurization process and storage conditions was never studied before, limiting the comprehensive understanding of the reasons for PBP instability. In this study, the stability of phycocyanobilin under high-pressure and high-temperature conditions was compared to the stability of phycobiliproteins. We revealed that phycobiliproteins have a higher color deterioration rate at 70–80 °C than at high-pressure (300–600 MPa) whereas phycocyanobilin remained stable during high-pressure and heat processing. During storage at pH 7, phycocyanobilin was oxidized, and the oxidation rate increased with increasing pH, while at lower pH phycocyanobilin had low solubility and resulted in aggregation.
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Affiliation(s)
- Hani Shkolnikov Lozober
- Faculty of Biotechnology and Food Engineering, Technion, Israel Institute of Technology, Haifa 3200003, Israel
| | - Zoya Okun
- Faculty of Biotechnology and Food Engineering, Technion, Israel Institute of Technology, Haifa 3200003, Israel
| | - Galit Parvari
- Faculty of Chemistry, Technion, Israel Institute of Technology, Haifa 3200003, Israel
| | - Avi Shpigelman
- Faculty of Biotechnology and Food Engineering, Technion, Israel Institute of Technology, Haifa 3200003, Israel
- Correspondence:
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4
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Pressure, motion, and conformational entropy in molecular recognition by proteins. BIOPHYSICAL REPORTS 2022; 3:100098. [PMID: 36647534 PMCID: PMC9840116 DOI: 10.1016/j.bpr.2022.100098] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/10/2022] [Accepted: 12/23/2022] [Indexed: 12/29/2022]
Abstract
The thermodynamics of molecular recognition by proteins is a central determinant of complex biochemistry. For over a half-century, detailed cryogenic structures have provided deep insight into the energetic contributions to ligand binding by proteins. More recently, a dynamical proxy based on NMR-relaxation methods has revealed an unexpected richness in the contributions of conformational entropy to the thermodynamics of ligand binding. Here, we report the pressure dependence of fast internal motion within the ribonuclease barnase and its complex with the protein barstar. In what we believe is a first example, we find that protein dynamics are conserved along the pressure-binding thermodynamic cycle. The femtomolar affinity of the barnase-barstar complex exists despite a penalty by -TΔSconf of +11.7 kJ/mol at ambient pressure. At high pressure, however, the overall change in side-chain dynamics is zero, and binding occurs with no conformational entropy penalty, suggesting an important role of conformational dynamics in the adaptation of protein function to extreme environments. Distinctive clustering of the pressure sensitivity is observed in response to both pressure and binding, indicating the presence of conformational heterogeneity involving less efficiently packed alternative conformation(s). The structural segregation of dynamics observed in barnase is striking and shows how changes in both the magnitude and the sign of regional contributions of conformational entropy to the thermodynamics of protein function are possible.
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5
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Pozza A, Giraud F, Cece Q, Casiraghi M, Point E, Damian M, Le Bon C, Moncoq K, Banères JL, Lescop E, Catoire LJ. Exploration of the dynamic interplay between lipids and membrane proteins by hydrostatic pressure. Nat Commun 2022; 13:1780. [PMID: 35365643 PMCID: PMC8975810 DOI: 10.1038/s41467-022-29410-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2021] [Accepted: 03/14/2022] [Indexed: 02/06/2023] Open
Abstract
Cell membranes represent a complex and variable medium in time and space of lipids and proteins. Their physico-chemical properties are determined by lipid components which can in turn influence the biological function of membranes. Here, we used hydrostatic pressure to study the close dynamic relationships between lipids and membrane proteins. Experiments on the β–barrel OmpX and the α–helical BLT2 G Protein-Coupled Receptor in nanodiscs of different lipid compositions reveal conformational landscapes intimately linked to pressure and lipids. Pressure can modify the conformational landscape of the membrane protein per se, but also increases the gelation of lipids, both being monitored simultaneously at high atomic resolution by NMR. Our study also clearly shows that a membrane protein can modulate, at least locally, the fluidity of the bilayer. The strategy proposed herein opens new perspectives to scrutinize the dynamic interplay between membrane proteins and their surrounding lipids. Direct information on the dynamic interplay between membrane proteins and lipids is scarce. Here the authors report a detailed description of these close relationships by combining lipid nanodiscs and high-pressure NMR. They report the link between pressure and lipid compositions to the conformational landscape of the β-barrel OmpX and the α-helical BLT2 G Protein-Coupled Receptor in nanodiscs.
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Affiliation(s)
- Alexandre Pozza
- Laboratoire de Biologie Physico-Chimique des Protéines Membranaires, UMR 7099, CNRS/Université de Paris, Institut de Biologie Physico-Chimique (IBPC, FRC 550), 75005, Paris, France
| | - François Giraud
- Institut de Chimie des Substances Naturelles (ICSN), CNRS UPR 2301, Université Paris-Saclay, 91198, Gif-sur-Yvette, France
| | - Quentin Cece
- Laboratoire de Biologie Physico-Chimique des Protéines Membranaires, UMR 7099, CNRS/Université de Paris, Institut de Biologie Physico-Chimique (IBPC, FRC 550), 75005, Paris, France.,Laboratoire Cibles Thérapeutiques et Conception de Médicaments (CiTCoM), UMR 8038, CNRS/Université de Paris, Faculté de Pharmacie, 75270, Paris, Cedex 06, France
| | - Marina Casiraghi
- Laboratoire de Biologie Physico-Chimique des Protéines Membranaires, UMR 7099, CNRS/Université de Paris, Institut de Biologie Physico-Chimique (IBPC, FRC 550), 75005, Paris, France.,Department of Molecular and Cellular Physiology, Stanford University School of Medicine, 94305, Stanford, CA, USA
| | - Elodie Point
- Laboratoire de Biologie Physico-Chimique des Protéines Membranaires, UMR 7099, CNRS/Université de Paris, Institut de Biologie Physico-Chimique (IBPC, FRC 550), 75005, Paris, France
| | - Marjorie Damian
- Institut des Biomolécules Max Mousseron (IBMM), Université de Montpellier, CNRS, ENSCM, Pôle Chimie Balard Recherche, 34293, Montpellier, cedex 5, France
| | - Christel Le Bon
- Laboratoire de Biologie Physico-Chimique des Protéines Membranaires, UMR 7099, CNRS/Université de Paris, Institut de Biologie Physico-Chimique (IBPC, FRC 550), 75005, Paris, France
| | - Karine Moncoq
- Laboratoire de Biologie Physico-Chimique des Protéines Membranaires, UMR 7099, CNRS/Université de Paris, Institut de Biologie Physico-Chimique (IBPC, FRC 550), 75005, Paris, France
| | - Jean-Louis Banères
- Institut des Biomolécules Max Mousseron (IBMM), Université de Montpellier, CNRS, ENSCM, Pôle Chimie Balard Recherche, 34293, Montpellier, cedex 5, France
| | - Ewen Lescop
- Institut de Chimie des Substances Naturelles (ICSN), CNRS UPR 2301, Université Paris-Saclay, 91198, Gif-sur-Yvette, France.
| | - Laurent J Catoire
- Laboratoire de Biologie Physico-Chimique des Protéines Membranaires, UMR 7099, CNRS/Université de Paris, Institut de Biologie Physico-Chimique (IBPC, FRC 550), 75005, Paris, France.
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6
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Gillilan RE. High-pressure SAXS, deep life, and extreme biophysics. Methods Enzymol 2022; 677:323-355. [DOI: 10.1016/bs.mie.2022.08.025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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7
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Gomes DC, Teixeira SCM, Leão JB, Razinkov VI, Qi W, Rodrigues MA, Roberts CJ. In Situ Monitoring of Protein Unfolding/Structural States under Cold High-Pressure Stress. Mol Pharm 2021; 18:4415-4427. [PMID: 34699230 DOI: 10.1021/acs.molpharmaceut.1c00604] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Biopharmaceutical formulations may be compromised by freezing, which has been attributed to protein conformational changes at a low temperature, and adsorption to ice-liquid interfaces. However, direct measurements of unfolding/conformational changes in sub-0 °C environments are limited because at ambient pressure, freezing of water can occur, which limits the applicability of otherwise commonly used analytical techniques without specifically tailored instrumentation. In this report, small-angle neutron scattering (SANS) and intrinsic fluorescence (FL) were used to provide in situ analysis of protein tertiary structure/folding at temperatures as low as -15 °C utilizing a high-pressure (HP) environment (up to 3 kbar) that prevents water from freezing. The results show that the α-chymotrypsinogen A (aCgn) structure is reasonably maintained under acidic pH (and corresponding pD) for all conditions of pressure and temperature tested. On the other hand, reversible structural changes and formation of oligomeric species were detected near -10 °C via HP-SANS for ovalbumin under neutral pD conditions. This was found to be related to the proximity of the temperature of cold denaturation of ovalbumin (TCD ∼ -17 °C; calculated via isothermal chemical denaturation and Gibbs-Helmholtz extrapolation) rather than a pressure effect. Significant structural changes were also observed for a monoclonal antibody, anti-streptavidin IgG1 (AS-IgG1), under acidic conditions near -5 °C and a pressure of ∼2 kbar. The conformational perturbation detected for AS-IgG1 is proposed to be consistent with the formation of unfolding intermediates such as molten globule states. Overall, the in situ approaches described here offer a means to characterize the conformational stability of biopharmaceuticals and proteins more generally under cold-temperature stress by the assessment of structural alteration, self-association, and reversibility of each process. This offers an alternative to current ex situ methods that are based on higher temperatures and subsequent extrapolation of the data and interpretations to the cold-temperature regime.
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Affiliation(s)
- Diana C Gomes
- Centro de Química Estrutural, Departamento de Engenharia Química, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa, Portugal.,Department of Chemical and Biomolecular Engineering, University of Delaware, 590 Avenue 1743, Newark, Delaware 19713, United States
| | - Susana C M Teixeira
- Department of Chemical and Biomolecular Engineering, University of Delaware, 590 Avenue 1743, Newark, Delaware 19713, United States.,NIST Center for Neutron Research, National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, Maryland 20899, United States
| | - Juscelino B Leão
- NIST Center for Neutron Research, National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, Maryland 20899, United States
| | - Vladimir I Razinkov
- Drug Product Development, Amgen Inc., Thousand Oaks, California 91320, United States
| | - Wei Qi
- Drug Product Development, Amgen Inc., Thousand Oaks, California 91320, United States
| | - Miguel A Rodrigues
- Centro de Química Estrutural, Departamento de Engenharia Química, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa, Portugal
| | - Christopher J Roberts
- Department of Chemical and Biomolecular Engineering, University of Delaware, 590 Avenue 1743, Newark, Delaware 19713, United States
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James EI, Murphree TA, Vorauer C, Engen JR, Guttman M. Advances in Hydrogen/Deuterium Exchange Mass Spectrometry and the Pursuit of Challenging Biological Systems. Chem Rev 2021; 122:7562-7623. [PMID: 34493042 PMCID: PMC9053315 DOI: 10.1021/acs.chemrev.1c00279] [Citation(s) in RCA: 101] [Impact Index Per Article: 33.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
![]()
Solution-phase hydrogen/deuterium
exchange (HDX) coupled to mass
spectrometry (MS) is a widespread tool for structural analysis across
academia and the biopharmaceutical industry. By monitoring the exchangeability
of backbone amide protons, HDX-MS can reveal information about higher-order
structure and dynamics throughout a protein, can track protein folding
pathways, map interaction sites, and assess conformational states
of protein samples. The combination of the versatility of the hydrogen/deuterium
exchange reaction with the sensitivity of mass spectrometry has enabled
the study of extremely challenging protein systems, some of which
cannot be suitably studied using other techniques. Improvements over
the past three decades have continually increased throughput, robustness,
and expanded the limits of what is feasible for HDX-MS investigations.
To provide an overview for researchers seeking to utilize and derive
the most from HDX-MS for protein structural analysis, we summarize
the fundamental principles, basic methodology, strengths and weaknesses,
and the established applications of HDX-MS while highlighting new
developments and applications.
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Affiliation(s)
- Ellie I James
- Department of Medicinal Chemistry, University of Washington, Seattle, Washington 98195, United States
| | - Taylor A Murphree
- Department of Medicinal Chemistry, University of Washington, Seattle, Washington 98195, United States
| | - Clint Vorauer
- Department of Medicinal Chemistry, University of Washington, Seattle, Washington 98195, United States
| | - John R Engen
- Department of Chemistry & Chemical Biology, Northeastern University, Boston, Massachusetts 02115, United States
| | - Miklos Guttman
- Department of Medicinal Chemistry, University of Washington, Seattle, Washington 98195, United States
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9
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Cardone C, Caseau CM, Bardiaux B, Thureaux A, Galloux M, Bajorek M, Eléouët JF, Litaudon M, Bontems F, Sizun C. A Structural and Dynamic Analysis of the Partially Disordered Polymerase-Binding Domain in RSV Phosphoprotein. Biomolecules 2021; 11:biom11081225. [PMID: 34439894 PMCID: PMC8392014 DOI: 10.3390/biom11081225] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2021] [Revised: 08/10/2021] [Accepted: 08/13/2021] [Indexed: 12/11/2022] Open
Abstract
The phosphoprotein P of Mononegavirales (MNV) is an essential co-factor of the viral RNA polymerase L. Its prime function is to recruit L to the ribonucleocapsid composed of the viral genome encapsidated by the nucleoprotein N. MNV phosphoproteins often contain a high degree of disorder. In Pneumoviridae phosphoproteins, the only domain with well-defined structure is a small oligomerization domain (POD). We previously characterized the differential disorder in respiratory syncytial virus (RSV) phosphoprotein by NMR. We showed that outside of RSV POD, the intrinsically disordered N-and C-terminal regions displayed a structural and dynamic diversity ranging from random coil to high helical propensity. Here we provide additional insight into the dynamic behavior of PCα, a domain that is C-terminal to POD and constitutes the RSV L-binding region together with POD. By using small phosphoprotein fragments centered on or adjacent to POD, we obtained a structural picture of the POD–PCα region in solution, at the single residue level by NMR and at lower resolution by complementary biophysical methods. We probed POD–PCα inter-domain contacts and showed that small molecules were able to modify the dynamics of PCα. These structural properties are fundamental to the peculiar binding mode of RSV phosphoprotein to L, where each of the four protomers binds to L in a different way.
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Affiliation(s)
- Christophe Cardone
- Institut de Chimie des Substances Naturelles, CNRS, Université Paris Saclay, 91190 Gif-sur-Yvette, France; (C.C.); (C.-M.C.); (M.L.); (F.B.)
| | - Claire-Marie Caseau
- Institut de Chimie des Substances Naturelles, CNRS, Université Paris Saclay, 91190 Gif-sur-Yvette, France; (C.C.); (C.-M.C.); (M.L.); (F.B.)
| | - Benjamin Bardiaux
- Structural Bioinformatics Unit, Department of Structural Biology and Chemistry, Institut Pasteur, CNRS UMR3528, 78015 Paris, France;
| | | | - Marie Galloux
- Unité de Virologie et Immunologie Moléculaires, INRAE, Université Paris Saclay, 78352 Jouy-en-Josas, France; (M.G.); (M.B.); (J.-F.E.)
| | - Monika Bajorek
- Unité de Virologie et Immunologie Moléculaires, INRAE, Université Paris Saclay, 78352 Jouy-en-Josas, France; (M.G.); (M.B.); (J.-F.E.)
| | - Jean-François Eléouët
- Unité de Virologie et Immunologie Moléculaires, INRAE, Université Paris Saclay, 78352 Jouy-en-Josas, France; (M.G.); (M.B.); (J.-F.E.)
| | - Marc Litaudon
- Institut de Chimie des Substances Naturelles, CNRS, Université Paris Saclay, 91190 Gif-sur-Yvette, France; (C.C.); (C.-M.C.); (M.L.); (F.B.)
| | - François Bontems
- Institut de Chimie des Substances Naturelles, CNRS, Université Paris Saclay, 91190 Gif-sur-Yvette, France; (C.C.); (C.-M.C.); (M.L.); (F.B.)
| | - Christina Sizun
- Institut de Chimie des Substances Naturelles, CNRS, Université Paris Saclay, 91190 Gif-sur-Yvette, France; (C.C.); (C.-M.C.); (M.L.); (F.B.)
- Correspondence:
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10
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Xu J, Janahar JJ, Park HW, Balasubramaniam V, Yousef AE. Influence of water activity and acidity on Bacillus cereus spore inactivation during combined high pressure-thermal treatment. Lebensm Wiss Technol 2021. [DOI: 10.1016/j.lwt.2021.111465] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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11
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Koss H, Honig B, Shapiro L, Palmer AG. Dimerization of Cadherin-11 involves multi-site coupled unfolding and strand swapping. Structure 2021; 29:1105-1115.e6. [PMID: 34166612 DOI: 10.1016/j.str.2021.06.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2021] [Revised: 05/01/2021] [Accepted: 06/04/2021] [Indexed: 10/21/2022]
Abstract
Cadherin extracellular domain 1 (EC1) mediates homophilic dimerization in adherens junctions. Conserved Trp2 and Trp4 residues in type II cadherins anchor the EC1 A strand intermolecularly in strand-swapped dimers. Herein, NMR spectroscopy is used to elucidate the roles of Trp2 and Trp4 in Cadherin-11 dimerization. The monomeric state, with the A strand and Trp side chains packed intramolecularly, is in equilibrium with sparsely populated partially and fully A-strand-exposed states, in which Trp2 (and Trp4, respectively) side-chain packing is disrupted. Exchange kinetics between the major state and the partially (fully) A-strand-exposed state is slow-intermediate (intermediate-fast). A separate very fast process exchanges ordered and random-coil BC-loop conformations with populations dependent on A-strand exposure and dimerization status. In addition, very slow processes connect the folded A-strand-exposed conformation to partially unfolded states, which may represent additional domain-swapping intermediates. The dimerization mechanism of type II cadherins is revealed as coupled folding and strand swapping.
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Affiliation(s)
- Hans Koss
- Department of Biochemistry and Molecular Biophysics, Columbia University Irving Medical Center, 701 West 168th Street, New York, NY 10032, USA
| | - Barry Honig
- Department of Biochemistry and Molecular Biophysics, Columbia University Irving Medical Center, 701 West 168th Street, New York, NY 10032, USA; Zuckerman Institute, Columbia University, 3227 Broadway, New York, NY 10027, USA; Department of Systems Biology, Columbia University Irving Medical Center, 1130 St. Nicholas Avenue, New York, NY 10032, USA; Department of Medicine, Columbia University Irving Medical Center, 630 West 168th Street, New York, NY 10032, USA
| | - Lawrence Shapiro
- Department of Biochemistry and Molecular Biophysics, Columbia University Irving Medical Center, 701 West 168th Street, New York, NY 10032, USA; Zuckerman Institute, Columbia University, 3227 Broadway, New York, NY 10027, USA
| | - Arthur G Palmer
- Department of Biochemistry and Molecular Biophysics, Columbia University Irving Medical Center, 701 West 168th Street, New York, NY 10032, USA.
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12
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Abstract
Fifty-five years ago, Norman Good and colleagues authored a paper that fundamentally advanced wet biochemistry [Good, N. E., Winget, G. D., Winter, W., Connolly, T. N., Izawa, S., and Singh, R. M. M. (1966) Hydrogen ion buffers for biological research. Biochemistry 5, 467-477] and in doing so has amassed more than 2500 citations. They laid out the properties required for useful, biochemically relevant hydrogen-ion buffers and then synthesized and tested 10 of them. Soon after, these buffers became commercially available. Since then, most of us never gave them a second thought. We just use them. Here, I discuss some of the background regarding the genesis of "Good's buffers", make a few (disparaging) observations about the non-Good's buffer, Tris, and suggest that we synthesize new buffers by combining the ideas of Good et al. with results from the past 60 years of protein chemistry.
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Affiliation(s)
- Gary J Pielak
- Department of Chemistry, Department of Biochemistry and Biophysics, Lineberger Comprehensive Cancer Center, and Integrative Program for Biological and Genome Sciences, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
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13
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Control of distal lysine coordination in a monomeric hemoglobin: A role for heme peripheral interactions. J Inorg Biochem 2021; 219:111437. [PMID: 33892380 DOI: 10.1016/j.jinorgbio.2021.111437] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2020] [Revised: 03/20/2021] [Accepted: 03/20/2021] [Indexed: 12/25/2022]
Abstract
THB1 is a monomeric truncated hemoglobin (TrHb) found in the cytoplasm of the green alga Chlamydomonas reinhardtii. The canonical heme coordination scheme in hemoglobins is a proximal histidine ligand and an open distal site. In THB1, the latter site is occupied by Lys53, which is likely to facilitate Fe(II)/Fe(III) redox cycling but hinders dioxygen binding, two features inherent to the NO dioxygenase activity of the protein. TrHb surveys show that a lysine at a position aligning with Lys53 is an insufficient determinant of coordination, and in this study, we sought to identify factors controlling lysine affinity for the heme iron. We solved the "Lys-off" X-ray structure of THB1, represented by the cyanide adduct of the Fe(III) protein, and hypothesized that interactions that differ between the known "Lys-on" structure and the Lys-off structure participate in the control of Lys53 affinity for the heme iron. We applied an experimental approach (site-directed mutagenesis, heme modification, pH titrations in the Fe(III) and Fe(II) states) and a computational approach (MD simulations in the Fe(II) state) to assess the role of heme propionate-protein interactions, distal helix capping, and the composition of the distal pocket. All THB1 modifications resulted in a weakening of lysine affinity and affected the coupling between Lys53 proton binding and heme redox potential. The results supported the importance of specific heme peripheral interactions for the pH stability of iron coordination and the ability of the protein to undergo redox reactions.
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14
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Xu X, Gagné D, Aramini JM, Gardner KH. Volume and compressibility differences between protein conformations revealed by high-pressure NMR. Biophys J 2021; 120:924-935. [PMID: 33524371 DOI: 10.1016/j.bpj.2020.12.034] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2020] [Revised: 11/25/2020] [Accepted: 12/21/2020] [Indexed: 12/12/2022] Open
Abstract
Proteins often interconvert between different conformations in ways critical to their function. Although manipulating such equilibria for biophysical study is often challenging, the application of pressure is a potential route to achieve such control by favoring the population of lower volume states. Here, we use this feature to study the interconversion of ARNT PAS-B Y456T, which undergoes a dramatic +3 slip in the β-strand register as it switches between two stably folded conformations. Using high-pressure biomolecular NMR approaches, we obtained the first, to our knowledge, quantitative data testing two key hypotheses of this process: the slipped conformation is both smaller and less compressible than the wild-type equivalent, and the interconversion proceeds through a chiefly unfolded intermediate state. Data collected in steady-state pressure and time-resolved pressure-jump modes, including observed pressure-dependent changes in the populations of the two conformers and increased rate of interconversion between conformers, support both hypotheses. Our work exemplifies how these approaches, which can be generally applied to protein conformational switches, can provide unique information that is not easily accessible through other techniques.
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Affiliation(s)
- Xingjian Xu
- Structural Biology Initiative, CUNY Advanced Science Research Center, New York, New York; Ph.D Program in Biochemistry, The Graduate Center, CUNY, New York, New York
| | - Donald Gagné
- Structural Biology Initiative, CUNY Advanced Science Research Center, New York, New York
| | - James M Aramini
- Structural Biology Initiative, CUNY Advanced Science Research Center, New York, New York
| | - Kevin H Gardner
- Structural Biology Initiative, CUNY Advanced Science Research Center, New York, New York; Department of Chemistry and Biochemistry, City College of New York, New York, New York; Ph.D. Programs in Biochemistry, Chemistry, and Biology, The Graduate Center, CUNY, New York, New York.
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15
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Barnes CA, Shen Y, Ying J, Bax A. Modulating the Stiffness of the Myosin VI Single α-Helical Domain. Biophys J 2020; 118:1119-1128. [PMID: 32049057 DOI: 10.1016/j.bpj.2020.01.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2019] [Revised: 12/20/2019] [Accepted: 01/02/2020] [Indexed: 11/28/2022] Open
Abstract
Highly charged, single α-helical (SAH) domains contain a high percentage of Arg, Lys, and Glu residues. Their dynamic salt bridge pairing creates the exceptional stiffness of these helical rods, with a persistence length of more than 200 Å for the myosin VI SAH domain. With the aim of modulating the stiffness of the helical structure, we investigated the effect, using NMR spectroscopy, of substituting key charged Arg, Lys, Glu, and Asp residues by Gly or His. Results indicate that such mutations result in the transient breaking of the helix at the site of mutation but with noticeable impact on amide hydrogen exchange rates extending as far as ±2 helical turns, pointing to a substantial degree of cooperativity in SAH stability. Whereas a single Gly substitution caused transient breaks ∼20% of the time, two consecutive Gly substitutions break the helix ∼65% of the time. NMR relaxation measurements indicate that the exchange rate between an intact and a broken helix is fast (>300,000 s-1) and that for the wild-type sequence, the finite persistence length is dominated by thermal fluctuations of backbone torsion angles and H-bond lengths, not by transient helix breaking. The double mutation D27H/E28H causes a pH-dependent fraction of helix disruption, in which the helix breakage increases from 26% at pH 7.5 to 53% at pH 5.5. The ability to modulate helical integrity by pH may enable incorporation of externally tunable dynamic components in the design of molecular machines.
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Affiliation(s)
- C Ashley Barnes
- Laboratory of Chemical Physics, NIDDK, National Institutes of Health, Bethesda, Maryland
| | - Yang Shen
- Laboratory of Chemical Physics, NIDDK, National Institutes of Health, Bethesda, Maryland
| | - Jinfa Ying
- Laboratory of Chemical Physics, NIDDK, National Institutes of Health, Bethesda, Maryland
| | - Ad Bax
- Laboratory of Chemical Physics, NIDDK, National Institutes of Health, Bethesda, Maryland.
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16
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Shkolnikov H, Belochvostov V, Okun Z, Shpigelman A. The effect of pressure on the kinetics of polyphenolics degradation – Implications to hyperbaric storage using Epigallocatechin-gallate as a model. INNOV FOOD SCI EMERG 2020. [DOI: 10.1016/j.ifset.2019.102273] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
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17
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Abiko LA, Grahl A, Grzesiek S. High Pressure Shifts the β 1-Adrenergic Receptor to the Active Conformation in the Absence of G Protein. J Am Chem Soc 2019; 141:16663-16670. [PMID: 31564099 DOI: 10.1021/jacs.9b06042] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
G protein-coupled receptors (GPCRs) are versatile chemical sensors, which transmit the signal of an extracellular binding event across the plasma membrane to the intracellular side. This function is achieved via the modulation of highly dynamical equilibria of various conformational receptor states. Here we have probed the effect of pressure on the conformational equilibria of a functional thermostabilized β1-adrenergic GPCR (β1AR) by solution NMR. High pressure induces a large shift in the conformational equilibrium (midpoint ∼600 bar) from the preactive conformation of agonist-bound β1AR to the fully active conformation, which under normal pressure is only populated when a G protein or a G protein-mimicking nanobody (Nb) binds to the intracellular side of the β1AR·agonist complex. No such large effects are observed for an antagonist-bound β1AR or the ternary β1AR·agonist·Nb80 complex. The detected structural changes of agonist-bound β1AR around the orthosteric ligand binding pocket indicate that the fully active receptor occupies an ∼100 Å3 smaller volume than that of its preactive form. Most likely, this volume reduction is caused by the compression of empty (nonhydrated) cavities in the ligand binding pocket and the center of the receptor, which increases the ligand receptor interactions and explains the ∼100-fold affinity increase of agonists in the presence of G protein. The finding that isotropic pressure induces a directed motion from the preactive to the fully active GPCR conformation provides evidence of the high mechanical robustness of this important functional switch.
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Affiliation(s)
- Layara Akemi Abiko
- Focal Area Structural Biology and Biophysics, Biozentrum , University of Basel , CH-4056 Basel , Switzerland
| | - Anne Grahl
- Focal Area Structural Biology and Biophysics, Biozentrum , University of Basel , CH-4056 Basel , Switzerland
| | - Stephan Grzesiek
- Focal Area Structural Biology and Biophysics, Biozentrum , University of Basel , CH-4056 Basel , Switzerland
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18
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19
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Samuelsen L, Holm R, Lathuile A, Schönbeck C. Buffer solutions in drug formulation and processing: How pKa values depend on temperature, pressure and ionic strength. Int J Pharm 2019; 560:357-364. [DOI: 10.1016/j.ijpharm.2019.02.019] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2018] [Revised: 02/08/2019] [Accepted: 02/09/2019] [Indexed: 11/16/2022]
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20
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Local unfolding of the HSP27 monomer regulates chaperone activity. Nat Commun 2019; 10:1068. [PMID: 30842409 PMCID: PMC6403371 DOI: 10.1038/s41467-019-08557-8] [Citation(s) in RCA: 77] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2017] [Accepted: 12/20/2018] [Indexed: 12/21/2022] Open
Abstract
The small heat-shock protein HSP27 is a redox-sensitive molecular chaperone that is expressed throughout the human body. Here, we describe redox-induced changes to the structure, dynamics, and function of HSP27 and its conserved α-crystallin domain (ACD). While HSP27 assembles into oligomers, we show that the monomers formed upon reduction are highly active chaperones in vitro, but are susceptible to self-aggregation. By using relaxation dispersion and high-pressure nuclear magnetic resonance (NMR) spectroscopy, we observe that the pair of β-strands that mediate dimerisation partially unfold in the monomer. We note that numerous HSP27 mutations associated with inherited neuropathies cluster to this dynamic region. High levels of sequence conservation in ACDs from mammalian sHSPs suggest that the exposed, disordered interface present in free monomers or oligomeric subunits may be a general, functional feature of sHSPs. The small heat-shock protein HSP27 occurs predominantly in oligomeric forms, which makes its structural characterisation challenging. Here the authors employ CPMG and high-pressure NMR with native mass spectrometry and biophysical assays to show that the active monomeric form of HSP27 is substantially disordered and highly chaperone-active.
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21
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Caro JA, Wand AJ. Practical aspects of high-pressure NMR spectroscopy and its applications in protein biophysics and structural biology. Methods 2018; 148:67-80. [PMID: 29964175 PMCID: PMC6133745 DOI: 10.1016/j.ymeth.2018.06.012] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2018] [Revised: 06/25/2018] [Accepted: 06/26/2018] [Indexed: 01/15/2023] Open
Abstract
Pressure and temperature are the two fundamental variables of thermodynamics. Temperature and chemical perturbation are central experimental tools for the exploration of macromolecular structure and dynamics. Though it has long been recognized that hydrostatic pressure offers a complementary and often unique view of macromolecular structure, stability and dynamics, it has not been employed nearly as much. For solution NMR applications the limited use of high-pressure is undoubtedly traced to difficulties of employing pressure in the context of modern multinuclear and multidimensional NMR. Limitations in pressure tolerant NMR sample cells have been overcome and enable detailed studies of macromolecular energy landscapes, hydration, dynamics and function. Here we review the practical considerations for studies of biological macromolecules at elevated pressure, with a particular emphasis on applications in protein biophysics and structural biology.
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Affiliation(s)
- José A Caro
- Johnson Research Foundation and Department of Biochemistry and Biophysics, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104-6509, United States
| | - A Joshua Wand
- Johnson Research Foundation and Department of Biochemistry and Biophysics, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104-6509, United States.
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22
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Jenkins KA, Fossat MJ, Zhang S, Rai DK, Klein S, Gillilan R, White Z, Gerlich G, McCallum SA, Winter R, Gruner SM, Barrick D, Royer CA. The consequences of cavity creation on the folding landscape of a repeat protein depend upon context. Proc Natl Acad Sci U S A 2018; 115:E8153-E8161. [PMID: 30104366 PMCID: PMC6126725 DOI: 10.1073/pnas.1807379115] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The effect of introducing internal cavities on protein native structure and global stability has been well documented, but the consequences of these packing defects on folding free-energy landscapes have received less attention. We investigated the effects of cavity creation on the folding landscape of the leucine-rich repeat protein pp32 by high-pressure (HP) and urea-dependent NMR and high-pressure small-angle X-ray scattering (HPSAXS). Despite a modest global energetic perturbation, cavity creation in the N-terminal capping motif (N-cap) resulted in very strong deviation from two-state unfolding behavior. In contrast, introduction of a cavity in the most stable, C-terminal half of pp32 led to highly concerted unfolding, presumably because the decrease in stability by the mutations attenuated the N- to C-terminal stability gradient present in WT pp32. Interestingly, enlarging the central cavity of the protein led to the population under pressure of a distinct intermediate in which the N-cap and repeats 1-4 were nearly completely unfolded, while the fifth repeat and the C-terminal capping motif remained fully folded. Thus, despite modest effects on global stability, introducing internal cavities can have starkly distinct repercussions on the conformational landscape of a protein, depending on their structural and energetic context.
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Affiliation(s)
- Kelly A Jenkins
- Graduate Program in Biochemistry and Biophysics, Rensselaer Polytechnic Institute, Troy, NY 12180
| | - Martin J Fossat
- Department of Biological Sciences, Rensselaer Polytechnic Institute, Troy, NY 12180
| | - Siwen Zhang
- Department of Chemistry and Chemical Biology, Rensselaer Polytechnic Institute, Troy, NY 12180
| | - Durgesh K Rai
- Cornell High Energy Synchrotron Source, Cornell University, Ithaca, NY 14853
| | - Sean Klein
- T. C. Jenkins Department of Biophysics, Johns Hopkins University, Baltimore, MD 21218
| | - Richard Gillilan
- Cornell High Energy Synchrotron Source, Cornell University, Ithaca, NY 14853
| | - Zackary White
- Department of Biomedical Engineering, Rensselaer Polytechnic Institute, Troy, NY 12180
| | - Grayson Gerlich
- Department of Biomedical Engineering, Rensselaer Polytechnic Institute, Troy, NY 12180
| | - Scott A McCallum
- Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, NY 12180
| | - Roland Winter
- Department of Physical Chemistry, Technical University of Dortmund, 44227 Dortmund, Germany
| | - Sol M Gruner
- Cornell High Energy Synchrotron Source, Cornell University, Ithaca, NY 14853
- Department of Physics, Cornell University, Ithaca, NY 14853
- Kavli Institute at Cornell for Nanoscale Science, Cornell University, Ithaca, NY 14853
| | - Doug Barrick
- T. C. Jenkins Department of Biophysics, Johns Hopkins University, Baltimore, MD 21218
| | - Catherine A Royer
- Graduate Program in Biochemistry and Biophysics, Rensselaer Polytechnic Institute, Troy, NY 12180;
- Department of Biological Sciences, Rensselaer Polytechnic Institute, Troy, NY 12180
- Department of Chemistry and Chemical Biology, Rensselaer Polytechnic Institute, Troy, NY 12180
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23
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Roche J, Royer CA, Roumestand C. Monitoring protein folding through high pressure NMR spectroscopy. PROGRESS IN NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY 2017; 102-103:15-31. [PMID: 29157491 DOI: 10.1016/j.pnmrs.2017.05.003] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/20/2017] [Revised: 05/31/2017] [Accepted: 05/31/2017] [Indexed: 06/07/2023]
Abstract
High-pressure is a well-known perturbation method used to destabilize globular proteins. It is perfectly reversible, which is essential for a proper thermodynamic characterization of a protein equilibrium. In contrast to other perturbation methods such as heat or chemical denaturant that destabilize protein structures uniformly, pressure exerts local effects on regions or domains of a protein containing internal cavities. When combined with NMR spectroscopy, hydrostatic pressure offers the possibility to monitor at a residue level the structural transitions occurring upon unfolding and to determine the kinetic properties of the process. High-pressure NMR experiments can now be routinely performed, owing to the recent development of commercially available high-pressure sample cells. This review summarizes recent advances and some future directions of high-pressure NMR techniques for the characterization at atomic resolution of the energy landscape of protein folding.
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Affiliation(s)
- Julien Roche
- Roy J. Carver Department of Biochemistry, Biophysics and Molecular Biology, Iowa State University, Ames, IA 50011, USA
| | - Catherine A Royer
- Department of Biological Sciences, Rensselaer Polytechnic Institute, Troy, NY 12180, USA
| | - Christian Roumestand
- Centre de Biochimie Structural INSERM U1054, CNRS UMMR 5058, Université de Montpellier, Montpellier 34090, France.
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24
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van Nassau TJ, Lenz CA, Scherzinger AS, Vogel RF. Combination of endolysins and high pressure to inactivate Listeria monocytogenes. Food Microbiol 2017; 68:81-88. [PMID: 28800829 DOI: 10.1016/j.fm.2017.06.005] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2016] [Revised: 04/03/2017] [Accepted: 06/04/2017] [Indexed: 01/08/2023]
Abstract
Outbreaks of listeriosis are often related to the consumption of low-processed ready-to-eat food products (e.g. soft cheeses or smoked fish) contaminated with Listeria monocytogenes. Traditional preservation techniques, such as heat treatment, cannot eliminate Listeria from these products without strongly affecting the quality of the foods. We therefore investigated the use of endolysin (PlyP40, Ply511, or PlyP825) in combination with high hydrostatic pressure processing to kill L. monocytogenes in buffer. The results demonstrated a more than additive effect when both treatments were combined. For example, whereas 0.16 μg/mL PlyP825 or 300 MPa (1 min, 30 °C) applied individually reduced the cell count by 0.2 and 0.3 log cfu, respectively, a combined treatment resulted in a reduction of 5.5 log cfu. Similar results were obtained for the other endolysins combined with high pressure processing. We also showed that the synergistic inactivation of cells by endolysin and HHP is possible at a pressure level of only 200 MPa (2 min, 30 °C). Thus, the application of endolysins did not only substantially increase the bactericidal effect of high pressure, but it also enabled the inactivation of bacterial cells at much lower pressure levels. This shows the potential of using such combined processes for the inactivation of L. monocytogenes and food preservation.
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Affiliation(s)
- Tomas J van Nassau
- Lehrstuhl für Technische Mikrobiologie, Technische Universität München, Gregor-Mendel-Str. 4, D-85354 Freising, Germany
| | - Christian A Lenz
- Lehrstuhl für Technische Mikrobiologie, Technische Universität München, Gregor-Mendel-Str. 4, D-85354 Freising, Germany
| | | | - Rudi F Vogel
- Lehrstuhl für Technische Mikrobiologie, Technische Universität München, Gregor-Mendel-Str. 4, D-85354 Freising, Germany.
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25
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Fuglestad B, Stetz MA, Belnavis Z, Wand AJ. Solution NMR investigation of the response of the lactose repressor core domain dimer to hydrostatic pressure. Biophys Chem 2017; 231:39-44. [PMID: 28249763 DOI: 10.1016/j.bpc.2017.02.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2017] [Revised: 02/21/2017] [Accepted: 02/22/2017] [Indexed: 11/19/2022]
Abstract
Previous investigations of the sensitivity of the lac repressor to high-hydrostatic pressure have led to varying conclusions. Here high-pressure solution NMR spectroscopy is used to provide an atomic level view of the pressure induced structural transition of the lactose repressor regulatory domain (LacI* RD) bound to the ligand IPTG. As the pressure is raised from ambient to 3kbar the native state of the protein is converted to a partially unfolded form. Estimates of rotational correlation times using transverse optimized relaxation indicates that a monomeric state is never reached and that the predominate form of the LacI* RD is dimeric throughout this pressure change. Spectral analysis suggests that the pressure-induced transition is localized and is associated with a volume change of approximately -115mlmol-1 and an average pressure dependent change in compressibility of approximately 30mlmol-1kbar-1. In addition, a subset of resonances emerge at high-pressures indicating the presence of a non-native but folded alternate state.
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Affiliation(s)
- Brian Fuglestad
- Johnson Research Foundation, Department of Biochemistry and Biophysics, University of Pennsylvania Perelman School of Medicine, 905 Stellar-Chance Laboratories, 422 Curie Blvd, Philadelphia, PA 19104-6059, USA
| | - Matthew A Stetz
- Johnson Research Foundation, Department of Biochemistry and Biophysics, University of Pennsylvania Perelman School of Medicine, 905 Stellar-Chance Laboratories, 422 Curie Blvd, Philadelphia, PA 19104-6059, USA
| | - Zachary Belnavis
- Johnson Research Foundation, Department of Biochemistry and Biophysics, University of Pennsylvania Perelman School of Medicine, 905 Stellar-Chance Laboratories, 422 Curie Blvd, Philadelphia, PA 19104-6059, USA
| | - A Joshua Wand
- Johnson Research Foundation, Department of Biochemistry and Biophysics, University of Pennsylvania Perelman School of Medicine, 905 Stellar-Chance Laboratories, 422 Curie Blvd, Philadelphia, PA 19104-6059, USA.
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26
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Preimesberger MR, Majumdar A, Lecomte JTJ. Dynamics of Lysine as a Heme Axial Ligand: NMR Analysis of the Chlamydomonas reinhardtii Hemoglobin THB1. Biochemistry 2017; 56:551-569. [DOI: 10.1021/acs.biochem.6b00926] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Matthew R. Preimesberger
- T.
C. Jenkins Department of Biophysics, Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - Ananya Majumdar
- Biomolecular
NMR Center, Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - Juliette T. J. Lecomte
- T.
C. Jenkins Department of Biophysics, Johns Hopkins University, Baltimore, Maryland 21218, United States
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27
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Schneidereit D, Vass H, Reischl B, Allen RJ, Friedrich O. Calcium Sensitive Fluorescent Dyes Fluo-4 and Fura Red under Pressure: Behaviour of Fluorescence and Buffer Properties under Hydrostatic Pressures up to 200 MPa. PLoS One 2016; 11:e0164509. [PMID: 27764134 PMCID: PMC5072694 DOI: 10.1371/journal.pone.0164509] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2016] [Accepted: 09/26/2016] [Indexed: 11/18/2022] Open
Abstract
The fluorescent Ca2+ sensitive dyes Fura Red (ratiometric) and Fluo-4 (non-ratiometric) are widely utilized for the optical assessment of Ca2+ fluctuations in vitro as well as in situ. The fluorescent behavior of these dyes is strongly depends on temperature, pH, ionic strength and pressure. It is crucial to understand the response of these dyes to pressure when applying calcium imaging technologies in the field of high pressure bioscience. Therefore, we use an optically accessible pressure vessel to pressurize physiological Ca2+-buffered solutions at different fixed concentrations of free Ca2+ (1 nM to 25.6 μM) and a specified dye concentration (12 μM) to pressures of 200 MPa, and record dye fluorescence intensity. Our results show that Fluo-4 fluorescence intensity is reduced by 31% per 100 MPa, the intensity of Fura Red is reduced by 10% per 100 MPa. The mean reaction volume for the dissociation of calcium from the dye molecules [Formula: see text] is determined to -17.8 ml mol-1 for Fluo-4 and -21.3 ml mol-1 for Fura Red. Additionally, a model is presented that is used to correct for pressure-dependent changes in pH and binding affinity of Ca2+ to EGTA, as well as to determine the influence of these changes on dye fluorescence.
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Affiliation(s)
- D. Schneidereit
- Institute of Medical Biotechnology, Friedrich-Alexander-University Erlangen-Nuernberg, 91052 Erlangen, Bavaria, Germany
- Erlangen Graduate School in Advanced Optical Technologies (SAOT), Friedrich-Alexander-University Erlangen-Nuernberg, 91052 Erlangen, Bavaria, Germany
- * E-mail:
| | - H. Vass
- School of Physics and Astronomy, University of Edinburgh, Edinburgh EH9 3FD, Scotland, United Kingdom
| | - B. Reischl
- Institute of Medical Biotechnology, Friedrich-Alexander-University Erlangen-Nuernberg, 91052 Erlangen, Bavaria, Germany
| | - R. J. Allen
- School of Physics and Astronomy, University of Edinburgh, Edinburgh EH9 3FD, Scotland, United Kingdom
| | - O. Friedrich
- Institute of Medical Biotechnology, Friedrich-Alexander-University Erlangen-Nuernberg, 91052 Erlangen, Bavaria, Germany
- Erlangen Graduate School in Advanced Optical Technologies (SAOT), Friedrich-Alexander-University Erlangen-Nuernberg, 91052 Erlangen, Bavaria, Germany
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28
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Ramos SJ, Chiquirrín M, García S, Condón S, Pérez MD. Effect of high pressure treatment on inactivation of vegetative pathogens and on denaturation of whey proteins in different media. Lebensm Wiss Technol 2015. [DOI: 10.1016/j.lwt.2015.03.085] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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29
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Georget E, Sevenich R, Reineke K, Mathys A, Heinz V, Callanan M, Rauh C, Knorr D. Inactivation of microorganisms by high isostatic pressure processing in complex matrices: A review. INNOV FOOD SCI EMERG 2015. [DOI: 10.1016/j.ifset.2014.10.015] [Citation(s) in RCA: 87] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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30
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Abstract
Fluorescence is the most widely used technique to study the effect of pressure on biochemical systems. The use of pressure as a physical variable sheds light into volumetric characteristics of reactions. Here we focus on the effect of pressure on protein solutions using a simple unfolding example in order to illustrate the applications of the methodology. Topics covered in this review include the relationships between practical aspects and technical limitations; the effect of pressure and the study of protein cavities; the interpretation of thermodynamic and relaxation kinetics; and the study of relaxation amplitudes. Finally, we discuss the insights available from the combination of fluorescence and other methods adapted to high pressure, such as SAXS or NMR. Because of the simplicity and accessibility of high-pressure fluorescence, the technique is a starting point that complements appropriately multi-methodological approaches related to understanding protein function, disfunction, and folding from the volumetric point of view.
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31
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Effect of pressure-induced changes in the ionization equilibria of buffers on inactivation of Escherichia coli and Staphylococcus aureus by high hydrostatic pressure. Appl Environ Microbiol 2013; 79:4041-7. [PMID: 23624471 DOI: 10.1128/aem.00469-13] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Survival rates of Escherichia coli and Staphylococcus aureus after high-pressure treatment in buffers that had large or small reaction volumes (ΔV°), and which therefore underwent large or small changes in pH under pressure, were compared. At a low buffer concentration of 0.005 M, survival was, as expected, better in MOPS (morpholinepropanesulfonic acid), HEPES, and Tris, whose ΔV° values are approximately 5.0 to 7.0 cm(3) mol(-1), than in phosphate or dimethyl glutarate (DMG), whose ΔV° values are about -25 cm(3) mol(-1). However, at a concentration of 0.1 M, survival was unexpectedly better in phosphate and DMG than in MOPS, HEPES, or Tris. This was because the baroprotective effect of phosphate and DMG increased much more rapidly with increasing concentration than it did with MOPS, HEPES, or Tris. Further comparisons of survival in solutions of salts expected to cause large electrostriction effects (Na2SO4 and CaCl2) and those causing lower electrostriction (NaCl and KCl) were made. The salts with divalent ions were protective at much lower concentrations than salts with monovalent ions. Buffers and salts both protected against transient membrane disruption in E. coli, but the molar concentrations necessary for membrane protection were much lower for phosphate and Na2SO4 than for HEPES and NaCl. Possible protective mechanisms discussed include effects of electrolytes on water compressibility and kosmotropic and specific ion effects. The results of this systematic study will be of considerable practical significance in studies of pressure inactivation of microbes under defined conditions but also raise important fundamental questions regarding the mechanisms of baroprotection by ionic solutes.
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Timson MJ, Duff MR, Dickey G, Saxton AM, Reyes-De-Corcuera JI, Howell EE. Further studies on the role of water in R67 dihydrofolate reductase. Biochemistry 2013; 52:2118-27. [PMID: 23458706 DOI: 10.1021/bi301544k] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Previous osmotic pressure studies of two nonhomologous dihydrofolate reductase (DHFR) enzymes found tighter binding of the nicotinamide adenine dinucleotide phosphate cofactor upon addition of neutral osmolytes. This result is consistent with water release accompanying binding. In contrast, osmotic stress studies found weaker binding of the dihydrofolate (DHF) substrate for both type I and type II DHFRs in the presence of osmolytes; this observation can be explained if dihydrofolate interacts with osmolytes and shifts the equilibrium from the enzyme-bound state toward the unbound substrate. Nuclear magnetic resonance experiments support this hypothesis, finding that osmolytes interact with dihydrofolate. To consider binding without added osmolytes, a high-pressure approach was used. In this study, the type II enzyme, R67 DHFR, was subjected to high hydrostatic pressure (HHP). Both enzyme activity and fluorescence measurements find the protein tolerates pressures up to 200 MPa. Binding of the cofactor to R67 DHFR weakens with increasing pressure, and a positive association volume of 11.4 ± 0.5 cm(3)/mol was measured. Additionally, an activation volume of 3.3 ± 0.5 cm(3)/mol describing k(cat)/K(m(DHF)) was determined from progress curve analysis. Results from these HHP experiments suggest water release accompanies binding of both the cofactor and DHF to R67 DHFR. In an additional set of experiments, isothermal titration calorimetry studies in H2O and D2O find that water reorganization dominates the enthalpy associated with binding of DHF to R67 DHFR·NADP(+), while no obvious effects occur for cofactor binding. The combined results indicate that water plays an active role in ligand binding to R67 DHFR.
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Affiliation(s)
- Mary Jane Timson
- Department of Biochemistry and Cellular and Molecular Biology, University of Tennessee , Knoxville, Tennessee 37996-0840, United States
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Koehler J, Beck Erlach M, Crusca E, Kremer W, Munte CE, Kalbitzer HR. Pressure Dependence of 15N Chemical Shifts in Model Peptides Ac-Gly-Gly-X-Ala-NH2. MATERIALS 2012. [PMCID: PMC5449040 DOI: 10.3390/ma5101774] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
High pressure NMR spectroscopy has developed into an important tool for studying conformational equilibria of proteins in solution. We have studied the amide proton and nitrogen chemical shifts of the 20 canonical amino acids X in the random-coil model peptide Ac-Gly-Gly-X-Ala-NH2, in a pressure range from 0.1 to 200 MPa, at a proton resonance frequency of 800 MHz. The obtained data allowed the determination of first and second order pressure coefficients with high accuracy at 283 K and pH 6.7. The mean first and second order pressure coefficients <B115N> and <B215N> for nitrogen are 2.91 ppm/GPa and −2.32 ppm/GPa2, respectively. The corresponding values <B11H> and <B21H> for the amide protons are 0.52 ppm/GPa and −0.41 ppm/GPa2. Residual dependent 1J1H15N-coupling constants are shown.
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Affiliation(s)
- Joerg Koehler
- Institute of Biophysics and Physical Biochemistry and Centre of Magnetic Resonance in Chemistry and Biomedicine, University of Regensburg, Regensburg 93040, Germany; E-Mails: (J.K.); (M.B.E.); (W.K.)
| | - Markus Beck Erlach
- Institute of Biophysics and Physical Biochemistry and Centre of Magnetic Resonance in Chemistry and Biomedicine, University of Regensburg, Regensburg 93040, Germany; E-Mails: (J.K.); (M.B.E.); (W.K.)
| | - Edson Crusca
- Physics Institute of São Carlos, University of São Paulo, São Carlos 13566-590, Brazil; E-Mails: (E.C.); (C.E.M.)
| | - Werner Kremer
- Institute of Biophysics and Physical Biochemistry and Centre of Magnetic Resonance in Chemistry and Biomedicine, University of Regensburg, Regensburg 93040, Germany; E-Mails: (J.K.); (M.B.E.); (W.K.)
| | - Claudia E. Munte
- Physics Institute of São Carlos, University of São Paulo, São Carlos 13566-590, Brazil; E-Mails: (E.C.); (C.E.M.)
| | - Hans Robert Kalbitzer
- Institute of Biophysics and Physical Biochemistry and Centre of Magnetic Resonance in Chemistry and Biomedicine, University of Regensburg, Regensburg 93040, Germany; E-Mails: (J.K.); (M.B.E.); (W.K.)
- Author to whom correspondence should be addressed; E-Mail: ; Tel.: +49-941-943-2594; Fax: +49-941-943-2479
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Nisius L, Grzesiek S. Key stabilizing elements of protein structure identified through pressure and temperature perturbation of its hydrogen bond network. Nat Chem 2012; 4:711-7. [PMID: 22914191 DOI: 10.1038/nchem.1396] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2011] [Accepted: 05/29/2012] [Indexed: 11/09/2022]
Abstract
Hydrogen bonds are key constituents of biomolecular structures, and their response to external perturbations may reveal important insights about the most stable components of a structure. NMR spectroscopy can probe hydrogen bond deformations at very high resolution through hydrogen bond scalar couplings (HBCs). However, the small size of HBCs has so far prevented a comprehensive quantitative characterization of protein hydrogen bonds as a function of the basic thermodynamic parameters of pressure and temperature. Using a newly developed pressure cell, we have now mapped pressure- and temperature-dependent changes of 31 hydrogen bonds in ubiquitin by measuring HBCs with very high precision. Short-range hydrogen bonds are only moderately perturbed, but many hydrogen bonds with large sequence separations (high contact order) show greater changes. In contrast, other high-contact-order hydrogen bonds remain virtually unaffected. The specific stabilization of such topologically important connections may present a general principle with which to achieve protein stability and to preserve structural integrity during protein function.
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Affiliation(s)
- Lydia Nisius
- Division of Structural Biology, Biozentrum, University of Basel, CH-4056 Basel, Switzerland
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Rosenbaum E, Gabel F, Durá MA, Finet S, Cléry-Barraud C, Masson P, Franzetti B. Effects of hydrostatic pressure on the quaternary structure and enzymatic activity of a large peptidase complex from Pyrococcus horikoshii. Arch Biochem Biophys 2011; 517:104-10. [PMID: 21896270 DOI: 10.1016/j.abb.2011.07.017] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2011] [Accepted: 07/31/2011] [Indexed: 10/17/2022]
Abstract
While molecular adaptation to high temperature has been extensively studied, the effect of hydrostatic pressure on protein structure and enzymatic activity is still poorly understood. We have studied the influence of pressure on both the quaternary structure and enzymatic activity of the dodecameric TET3 peptidase from Pyrococcus horikoshii. Small angle X-ray scattering (SAXS) revealed a high robustness of the oligomer under high pressure of up to 300 MPa at 25°C as well as at 90°C. The enzymatic activity of TET3 was enhanced by pressure up to 180 MPa. From the pressure behavior of the different rate-constants we have determined the volume changes associated with substrate binding and catalysis. Based on these results we propose that a change in the rate-limiting step occurs around 180 MPa.
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Affiliation(s)
- Eva Rosenbaum
- Group Extremophiles and Large Molecular Assemblies (ELMA), CEA, Institut de Biologie Structurale, Grenoble, France
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Reineke K, Mathys A, Knorr D. Shift of pH-Value During Thermal Treatments in Buffer Solutions and Selected Foods. INTERNATIONAL JOURNAL OF FOOD PROPERTIES 2011. [DOI: 10.1080/10942910903456978] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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Min SK, Samaranayake CP, Sastry SK. In Situ Measurement of Reaction Volume and Calculation of pH of Weak Acid Buffer Solutions Under High Pressure. J Phys Chem B 2011; 115:6564-71. [DOI: 10.1021/jp1110295] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Stephen K. Min
- Department of Food, Agricultural, and Biological Engineering, The Ohio State University, 590 Woody Hayes Drive, Columbus, Ohio 43210, United States
| | - Chaminda P. Samaranayake
- Department of Food, Agricultural, and Biological Engineering, The Ohio State University, 590 Woody Hayes Drive, Columbus, Ohio 43210, United States
| | - Sudhir K. Sastry
- Department of Food, Agricultural, and Biological Engineering, The Ohio State University, 590 Woody Hayes Drive, Columbus, Ohio 43210, United States
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Urayama P, Frey EW, Savage SR. Fluorescent probe dyes for metabolic-ion sensing under high hydrostatic pressures. Ann N Y Acad Sci 2010; 1189:104-12. [PMID: 20233375 DOI: 10.1111/j.1749-6632.2009.05184.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Fluorescence spectroscopy and microscopy imaging are widely used at ambient pressure for analytical studies on biological systems. Before using fluorescence-based methods at high pressures, biochemical and metabolic probes need to be characterized under pressure to ensure valid quantitative results. In this review, we describe the principles behind the use of fluorescent probe dyes for ion sensing and provide models for interpreting the dye spectrum under pressure. We then review results from three studies using the excited-state emission from probe dyes sensitive to pH and calcium-ion concentration, demonstrating some ways pressure may affect probe operation.
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Affiliation(s)
- Paul Urayama
- Department of Physics, Miami University, Oxford, Ohio 45056, USA.
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Using LysoSensor Yellow/Blue DND-160 to sense acidic pH under high hydrostatic pressures. Anal Biochem 2009; 384:359-61. [DOI: 10.1016/j.ab.2008.10.007] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2008] [Revised: 10/07/2008] [Accepted: 10/08/2008] [Indexed: 11/18/2022]
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Knorr D, Mathys A. Ultrahochdrucktechnik für innovative Behandlungsverfahren von Lebensmitteln. CHEM-ING-TECH 2008. [DOI: 10.1002/cite.200800068] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Salerno M, Ajimo JJ, Dudley JA, Binzel K, Urayama P. Characterization of dual-wavelength seminaphthofluorescein and seminapthorhodafluor dyes for pH sensing under high hydrostatic pressures. Anal Biochem 2006; 362:258-67. [PMID: 17274941 DOI: 10.1016/j.ab.2006.12.042] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2006] [Accepted: 12/23/2006] [Indexed: 11/16/2022]
Abstract
Hydrostatic pressure is an important physical parameter in biology, with pressures in the few-hundred-atm range having significant effects on cellular morphology, metabolism, and viability. To ensure valid results when studying pressure effects using fluorescence spectroscopy and imaging methods, metabolic probes need to be characterized for high-pressure use. Of interest is the sensing of pH at high pressures due to the key role that pH plays in cellular function. Despite the availability of pH-sensitive dyes, only a few have been characterized for high-pressure use. Here we present the effects of pressure on the acid-base equilibria of four dual-wavelength seminaphthorhodafluor and seminaphthofluorescein dyes (pK(a)=6.6-7.8). Using phosphate buffers as high-pressure pH references, we investigate the pressure dependence of pK(a) for these dyes and determine the volume change associated with the acid-dissociation reaction. We find that if pressure-induced pK(a) changes are not accounted for during interpretation of emission spectra, systematic errors of up to 0.02 pH units per 100atm would result, comparable to previously measured pressure-induced pH changes in vivo. Results are validated by correctly sensing pH changes in Tris and acetate solutions. Methods presented here are applicable to other metabolic probes utilizing dual-wavelength ratiometric sensing modes.
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Affiliation(s)
- Michael Salerno
- Department of Physics, Miami University, Oxford, OH 45056, USA
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Bataille C, Baldacchino G, Cosson RP, Coppo M, Trehen C, Vigneron G, Renault JP, Pin S. Effect of pressure on pulse radiolysis reduction of proteins. Biochim Biophys Acta Gen Subj 2005; 1724:432-9. [PMID: 15953680 DOI: 10.1016/j.bbagen.2005.04.021] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2005] [Revised: 04/19/2005] [Accepted: 04/21/2005] [Indexed: 11/24/2022]
Abstract
Pulse radiolysis experiments were performed on proteins under pressure. Whereas many spectroscopic techniques have shown protein modifications at different pressure ranges, the present measurements performed using the water radiolysis allowed to generate radical species and to study the mechanisms implied in their reactions with proteins. This work gives the first results obtained on the effects of pressure on the rate constants of the proteins reduction by the hydrated electron at pressures up to 100 MPa. The reaction with the hydrated electron was investigated on two classes of protein: the horse myoglobin and the mussel metallothioneins. We have successively studied the influence of the pH value of metmyoglobin solutions (pH 6, 7 and 8) and the influence of the metals nature (Zn,Cu,Cd) bound to metallothioneins. For both protein, whatever the experimental conditions, the pressure does not influence the value of the reduction rate constant in the investigated range (0.1-100 MPa).
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Affiliation(s)
- Céline Bataille
- Laboratoire Claude Fréjacques (URA 331 CEA/CNRS), DSM/DRECAM/Service de Chimie Moléculaire, CEA Saclay, 91191-Gif sur Yvette cedex, France
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