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Hancock JT. Are Protein Cavities and Pockets Commonly Used by Redox Active Signalling Molecules? PLANTS (BASEL, SWITZERLAND) 2023; 12:2594. [PMID: 37514209 PMCID: PMC10383989 DOI: 10.3390/plants12142594] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2023] [Revised: 06/23/2023] [Accepted: 07/05/2023] [Indexed: 07/30/2023]
Abstract
It has been well known for a long time that inert gases, such as xenon (Xe), have significant biological effects. As these atoms are extremely unlikely to partake in direct chemical reactions with biomolecules such as proteins, lipids, and nucleic acids, there must be some other mode of action to account for the effects reported. It has been shown that the topology of proteins allows for cavities and hydrophobic pockets, and it is via an interaction with such protein structures that inert gases are thought to have their action. Recently, it has been mooted that the relatively inert gas molecular hydrogen (H2) may also have its effects via such a mechanism, influencing protein structures and actions. H2 is thought to also act via interaction with redox active compounds, particularly the hydroxyl radical (·OH) and peroxynitrite (ONOO-), but not nitric oxide (NO·), superoxide anions (O2·-) or hydrogen peroxide (H2O2). However, instead of having a direct interaction with H2, is there any evidence that these redox compounds can also interact with Xe pockets and cavities in proteins, either having an independent effect on proteins or interfering with the action of inert gases? This suggestion will be explored here.
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Affiliation(s)
- John T Hancock
- School of Applied Sciences, University of the West of England, Bristol BS16 1QY, UK
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2
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Kim H, Kim JG, Muniyappan S, Kim TW, Lee SJ, Ihee H. Effect of Occluded Ligand Migration on the Kinetics and Structural Dynamics of Homodimeric Hemoglobin. J Phys Chem B 2020; 124:1550-1556. [PMID: 32027135 DOI: 10.1021/acs.jpcb.9b11749] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Small molecules such as molecular oxygen, nitric oxide, and carbon monoxide play important roles in life, and many proteins require the transport of small molecules to and from the bulk solvent for their function. Ligand migration within a protein molecule is expected to be closely related to the overall structural changes of the protein, but the detailed and quantitative connection remains elusive. For example, despite numerous studies, how occluded ligand migration affects the kinetics and structural dynamics of the R-T transition remains unclear. To shed light on this issue, we chose homodimeric hemoglobin (HbI) with the I114F mutation (I114F), which is known to interfere with ligand migration between the primary and secondary docking sites, and studied its kinetics and structural dynamics using time-resolved X-ray solution scattering. The kinetic analysis shows that I114F has three structurally distinct intermediates (I1, I2, and I3) as in the wild type (WT), but its geminate CO recombination occurs directly from I1 without the path via I2 observed in WT. Moreover, the structural transitions, which involve ligand migration (the transitions from I1 to I2 and from I3 to the initial state), are decelerated compared to WT. The structural analysis revealed that I114F involves generally smaller structural changes in all three intermediates compared to WT.
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Affiliation(s)
- Hanui Kim
- Department of Chemistry and KI for the BioCentury , KAIST , Daejeon 305-701 , Republic of Korea.,Center for Nanomaterials and Chemical Reactions , Institute for Basic Science (IBS) , Daejeon 305-701 , Republic of Korea
| | - Jong Goo Kim
- Department of Chemistry and KI for the BioCentury , KAIST , Daejeon 305-701 , Republic of Korea.,Center for Nanomaterials and Chemical Reactions , Institute for Basic Science (IBS) , Daejeon 305-701 , Republic of Korea
| | - Srinivasan Muniyappan
- Department of Chemistry and KI for the BioCentury , KAIST , Daejeon 305-701 , Republic of Korea.,Center for Nanomaterials and Chemical Reactions , Institute for Basic Science (IBS) , Daejeon 305-701 , Republic of Korea
| | - Tae Wu Kim
- Department of Chemistry and KI for the BioCentury , KAIST , Daejeon 305-701 , Republic of Korea.,Center for Nanomaterials and Chemical Reactions , Institute for Basic Science (IBS) , Daejeon 305-701 , Republic of Korea
| | - Sang Jin Lee
- Department of Chemistry and KI for the BioCentury , KAIST , Daejeon 305-701 , Republic of Korea.,Center for Nanomaterials and Chemical Reactions , Institute for Basic Science (IBS) , Daejeon 305-701 , Republic of Korea
| | - Hyotcherl Ihee
- Department of Chemistry and KI for the BioCentury , KAIST , Daejeon 305-701 , Republic of Korea.,Center for Nanomaterials and Chemical Reactions , Institute for Basic Science (IBS) , Daejeon 305-701 , Republic of Korea
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3
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Ardiccioni C, Arcovito A, Della Longa S, van der Linden P, Bourgeois D, Weik M, Montemiglio LC, Savino C, Avella G, Exertier C, Carpentier P, Prangé T, Brunori M, Colloc’h N, Vallone B. Ligand pathways in neuroglobin revealed by low-temperature photodissociation and docking experiments. IUCRJ 2019; 6:832-842. [PMID: 31576217 PMCID: PMC6760443 DOI: 10.1107/s2052252519008157] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/22/2019] [Accepted: 06/06/2019] [Indexed: 06/10/2023]
Abstract
A combined biophysical approach was applied to map gas-docking sites within murine neuroglobin (Ngb), revealing snapshots of events that might govern activity and dynamics in this unique hexacoordinate globin, which is most likely to be involved in gas-sensing in the central nervous system and for which a precise mechanism of action remains to be elucidated. The application of UV-visible microspectroscopy in crystallo, solution X-ray absorption near-edge spectroscopy and X-ray diffraction experiments at 15-40 K provided the structural characterization of an Ngb photolytic intermediate by cryo-trapping and allowed direct observation of the relocation of carbon monoxide within the distal heme pocket after photodissociation. Moreover, X-ray diffraction at 100 K under a high pressure of dioxygen, a physiological ligand of Ngb, unravelled the existence of a storage site for O2 in Ngb which coincides with Xe-III, a previously described docking site for xenon or krypton. Notably, no other secondary sites were observed under our experimental conditions.
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Affiliation(s)
- Chiara Ardiccioni
- Department of Life and Environmental Sciences, New York–Marche Structural Biology Center (NY-MaSBiC), Polytechnic University of Marche, Ancona, Italy
| | - Alessandro Arcovito
- Istituto di Biochimica e Biochimica Clinica, Universitá Cattolica del Sacro Cuore, Largo Francesco Vito 1, 00168 Rome, Italy
- Fondazione Policlinico Universitario Agostino Gemelli–IRCCS, Largo Francesco Vito 1, 00168 Rome, Italy
| | - Stefano Della Longa
- Department of Life, Health and Environmental Sciences, University of L’Aquila, 67100 L’Aquila, Italy
| | - Peter van der Linden
- European Synchrotron Radiation Facility (ESRF), 38043 Grenoble, France
- Partnership for Soft Condensed Matter (PSCM), 38043 Grenoble, France
| | | | - Martin Weik
- Université Grenoble Alpes, CEA, CNRS, IBS, 38000 Grenoble, France
| | - Linda Celeste Montemiglio
- Department of Biochemical Sciences ‘A. Rossi Fanelli’, University of Rome Sapienza, Piazzale Aldo Moro 5, 00185 Rome, Italy
- Institute of Molecular Biology and Pathology, National Research Council, Piazzale Aldo Moro 5, 00185 Rome, Italy
- Istituto Pasteur–Fondazione Cenci Bolognetti, Department of Biochemical Sciences ‘A. Rossi Fanelli’, University of Rome Sapienza, Piazzale Aldo Moro 5, 00185 Rome, Italy
| | - Carmelinda Savino
- Institute of Molecular Biology and Pathology, National Research Council, Piazzale Aldo Moro 5, 00185 Rome, Italy
| | - Giovanna Avella
- Department of Biochemical Sciences ‘A. Rossi Fanelli’, University of Rome Sapienza, Piazzale Aldo Moro 5, 00185 Rome, Italy
- Chemistry Department, Merck Serono S.p.A., Via Casilina 125, 00176 Rome, Italy
| | - Cécile Exertier
- Department of Biochemical Sciences ‘A. Rossi Fanelli’, University of Rome Sapienza, Piazzale Aldo Moro 5, 00185 Rome, Italy
| | - Philippe Carpentier
- European Synchrotron Radiation Facility (ESRF), 38043 Grenoble, France
- CEA/DRF/BIG/CBM/BioCat LCBM CNRS UMR 5249, Université Grenoble Alpes, 38000 Grenoble, France
| | - Thierry Prangé
- CiTeCoM UMR 8038 CNRS, Université Paris Descartes, Paris, France
| | - Maurizio Brunori
- Department of Biochemical Sciences ‘A. Rossi Fanelli’, University of Rome Sapienza, Piazzale Aldo Moro 5, 00185 Rome, Italy
| | - Nathalie Colloc’h
- ISTCT UMR 6030 CNRS Université de Caen Normandie CEA, CERVOxy Team, Centre Cyceron, Caen, France
| | - Beatrice Vallone
- Department of Biochemical Sciences ‘A. Rossi Fanelli’, University of Rome Sapienza, Piazzale Aldo Moro 5, 00185 Rome, Italy
- Institute of Molecular Biology and Pathology, National Research Council, Piazzale Aldo Moro 5, 00185 Rome, Italy
- Istituto Pasteur–Fondazione Cenci Bolognetti, Department of Biochemical Sciences ‘A. Rossi Fanelli’, University of Rome Sapienza, Piazzale Aldo Moro 5, 00185 Rome, Italy
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4
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Boubeta FM, Bieza SA, Bringas M, Estrin DA, Boechi L, Bari SE. Mechanism of Sulfide Binding by Ferric Hemeproteins. Inorg Chem 2018; 57:7591-7600. [DOI: 10.1021/acs.inorgchem.8b00478] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Fernando M. Boubeta
- Instituto de Química Física de los Materiales, Medio Ambiente y Energía (INQUIMAE), CONICET and Universidad de Buenos Aires, Buenos Aires 1053, Argentina
| | - Silvina A. Bieza
- Instituto de Química Física de los Materiales, Medio Ambiente y Energía (INQUIMAE), CONICET and Universidad de Buenos Aires, Buenos Aires 1053, Argentina
| | - Mauro Bringas
- Instituto de Química Física de los Materiales, Medio Ambiente y Energía (INQUIMAE), CONICET and Universidad de Buenos Aires, Buenos Aires 1053, Argentina
| | - Darío A. Estrin
- Instituto de Química Física de los Materiales, Medio Ambiente y Energía (INQUIMAE), CONICET and Universidad de Buenos Aires, Buenos Aires 1053, Argentina
| | | | - Sara E. Bari
- Instituto de Química Física de los Materiales, Medio Ambiente y Energía (INQUIMAE), CONICET and Universidad de Buenos Aires, Buenos Aires 1053, Argentina
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Bustamante JP, Szretter ME, Sued M, Martí MA, Estrin DA, Boechi L. A quantitative model for oxygen uptake and release in a family of hemeproteins. Bioinformatics 2016; 32:1805-13. [PMID: 27153569 DOI: 10.1093/bioinformatics/btw083] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2015] [Accepted: 01/30/2016] [Indexed: 11/14/2022] Open
Abstract
MOTIVATION Hemeproteins have many diverse functions that largely depend on the rate at which they uptake or release small ligands, like oxygen. These proteins have been extensively studied using either simulations or experiments, albeit only qualitatively and one or two proteins at a time. RESULTS We present a physical-chemical model, which uses data obtained exclusively from computer simulations, to describe the uptake and release of oxygen in a family of hemeproteins, called truncated hemoglobins (trHbs). Through a rigorous statistical analysis we demonstrate that our model successfully recaptures all the reported experimental oxygen association and dissociation kinetic rate constants, thus allowing us to establish the key factors that determine the rates at which these hemeproteins uptake and release oxygen. We found that internal tunnels as well as the distal site water molecules control ligand uptake, whereas oxygen stabilization by distal site residues controls ligand release. Because these rates largely determine the functions of these hemeproteins, these approaches will also be important tools in characterizing the trHbs members with unknown functions. CONTACT lboechi@ic.fcen.uba.ar SUPPLEMENTARY INFORMATION Supplementary data are available at Bioinformatics online.
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Affiliation(s)
- Juan P Bustamante
- Departamento de Química Inorgánica, Analítica Y Química Física, INQUIMAE-CONICET, Facultad De Ciencias Exactas Y Naturales, Universidad De Buenos Aires
| | - María E Szretter
- Instituto De Cálculo, Facultad De Ciencias Exactas Y Naturales, Universidad De Buenos Aires Departamento De Matemática, Facultad De Ciencias Exactas Y Naturales, Universidad De Buenos Aires
| | - Mariela Sued
- Instituto De Cálculo, Facultad De Ciencias Exactas Y Naturales, Universidad De Buenos Aires
| | - Marcelo A Martí
- Departamento De Química Biológica E Instituto De Química Biológica De La Facultad De Ciencias Exactas Y Naturales (IQUIBICEN), Universidad De Buenos Aires, Buenos Aires, Argentina
| | - Darío A Estrin
- Departamento de Química Inorgánica, Analítica Y Química Física, INQUIMAE-CONICET, Facultad De Ciencias Exactas Y Naturales, Universidad De Buenos Aires
| | - Leonardo Boechi
- Instituto De Cálculo, Facultad De Ciencias Exactas Y Naturales, Universidad De Buenos Aires
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Membrane-induced changes in the holomyoglobin tertiary structure: interplay with function. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2014; 43:317-29. [DOI: 10.1007/s00249-014-0964-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/03/2014] [Revised: 04/04/2014] [Accepted: 04/25/2014] [Indexed: 11/26/2022]
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7
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Hydrogen Peroxide Biosensor Based on Cellulose Diacetate Ionic Liquid Film Immobilizing Myoglobin. CHINESE JOURNAL OF ANALYTICAL CHEMISTRY 2012. [DOI: 10.3724/sp.j.1096.2011.01358] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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8
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Ma CW, Xiu ZL, Zeng AP. A new concept to reveal protein dynamics based on energy dissipation. PLoS One 2011; 6:e26453. [PMID: 22022616 PMCID: PMC3195717 DOI: 10.1371/journal.pone.0026453] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2011] [Accepted: 09/27/2011] [Indexed: 11/30/2022] Open
Abstract
Protein dynamics is essential for its function, especially for intramolecular signal transduction. In this work we propose a new concept, energy dissipation model, to systematically reveal protein dynamics upon effector binding and energy perturbation. The concept is applied to better understand the intramolecular signal transduction during allostery of enzymes. The E. coli allosteric enzyme, aspartokinase III, is used as a model system and special molecular dynamics simulations are designed and carried out. Computational results indicate that the number of residues affected by external energy perturbation (i.e. caused by a ligand binding) during the energy dissipation process shows a sigmoid pattern. Using the two-state Boltzmann equation, we define two parameters, the half response time and the dissipation rate constant, which can be used to well characterize the energy dissipation process. For the allostery of aspartokinase III, the residue response time indicates that besides the ACT2 signal transduction pathway, there is another pathway between the regulatory site and the catalytic site, which is suggested to be the β15-αK loop of ACT1. We further introduce the term “protein dynamical modules” based on the residue response time. Different from the protein structural modules which merely provide information about the structural stability of proteins, protein dynamical modules could reveal protein characteristics from the perspective of dynamics. Finally, the energy dissipation model is applied to investigate E. coli aspartokinase III mutations to better understand the desensitization of product feedback inhibition via allostery. In conclusion, the new concept proposed in this paper gives a novel holistic view of protein dynamics, a key question in biology with high impacts for both biotechnology and biomedicine.
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Affiliation(s)
- Cheng-Wei Ma
- Institute of Bioprocess and Biosystems Engineering, Hamburg University of Technology, Hamburg, Germany
- School of Life Science and Biotechnology, Dalian University of Technology, Dalian, China
| | - Zhi-Long Xiu
- School of Life Science and Biotechnology, Dalian University of Technology, Dalian, China
| | - An-Ping Zeng
- Institute of Bioprocess and Biosystems Engineering, Hamburg University of Technology, Hamburg, Germany
- * E-mail:
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9
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Hydrogen Peroxide Biosensor Based on Cellulose Diacetate-Ionic Liquid Film Immobilizing Myoglobin. CHINESE JOURNAL OF ANALYTICAL CHEMISTRY 2011. [DOI: 10.1016/s1872-2040(10)60471-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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10
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Time resolved thermodynamics associated with ligand photorelease in heme peroxidases and globins: Open access channels versus gated ligand release. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2011; 1814:1065-76. [PMID: 21278003 DOI: 10.1016/j.bbapap.2011.01.009] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2010] [Revised: 01/14/2011] [Accepted: 01/17/2011] [Indexed: 10/18/2022]
Abstract
Heme proteins represent a diverse class of biomolecules responsible for an extremely diverse array of physiological functions including electron transport, monooxygenation, ligand transport and storage, cellular signaling, respiration, etc. An intriguing aspect of these proteins is that such functional diversity is accomplished using a single type of heme macrocycle based upon iron protoporphyrin IX. The functional diversity originates from a delicate balance of inter-molecular interactions within the protein matrix together with well choreographed dynamics that modulate the heme electronic structure as well as ligand entry/exit pathways from the bulk solvent to the active site. Of particular interest are the dynamics and energetics associated with the entry/exit of ligands as this process plays a significant role in regulating the rates of heme protein activity. Time-resolved photoacoustic calorimetry (PAC) has emerged as a powerful tool through which to probe the underlying energetics associated with small molecule dissociation and release to the bulk solvent in heme proteins on time scales from tens of nanoseconds to several microseconds. In this review, the results of PAC studies on various classes of heme proteins are summarized highlighting how different protein structures affect the thermodynamics of ligand migration. This article is part of a Special Issue entitled: Protein Dynamics: Experimental and Computational Approaches.
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Nienhaus K, Nienhaus GU. Ligand dynamics in heme proteins observed by Fourier transform infrared-temperature derivative spectroscopy. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2010; 1814:1030-41. [PMID: 20656073 DOI: 10.1016/j.bbapap.2010.07.018] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/02/2010] [Revised: 07/14/2010] [Accepted: 07/15/2010] [Indexed: 11/29/2022]
Abstract
Fourier transform infrared (FTIR) spectroscopy is a powerful tool for the investigation of protein-ligand interactions in heme proteins. Nitric oxide and carbon monoxide are attractive physiologically relevant ligands because their bond stretching vibrations give rise to strong mid-infrared absorption bands that can be measured with exquisite sensitivity and precision using photolysis difference spectroscopy at cryogenic temperatures. These stretching bands are fine-tuned by electrostatic interactions with the environment and, therefore, ligands can be utilized as local probes of structure and dynamics. Bound to the heme iron, the ligand stretching bands are susceptible to changes in the iron-ligand bond and the electric field at the active site. Upon photolysis, the vibrational bands display changes due to ligand relocation to docking sites within the protein, rotational motions of the ligand in these sites and protein conformational changes. Photolysis difference spectra taken over a wide temperature range (3-300K) using specific temperature protocols for sample photodissociation can provide detailed insights into both protein and ligand dynamics. Moreover, temperature-derivative spectroscopy (TDS) has proven to be a particularly powerful technique to study protein-ligand interactions. The FTIR-TDS technique has been extensively applied to studies of carbon monoxide binding to heme proteins, whereas measurements with nitric oxide are still scarce. Here we describe infrared cryo-spectroscopy and present a variety of applications to the study of protein-ligand interactions in heme proteins. This article is part of a Special Issue entitled: Protein Dynamics: Experimental and Computational Approaches.
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Affiliation(s)
- Karin Nienhaus
- Karlsruhe Institute of Technology (KIT), Institute of Applied Physics and Center for Functional Nanostructures, Wolfgang-Gaede-Str. 1, D-76131 Karlsruhe, Germany
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Abstract
Cholesterol oxidase is a bacterial-specific flavoenzyme that catalyzes the oxidation and isomerisation of steroids containing a 3beta hydroxyl group and a double bond at the Delta5-6 of the steroid ring system. The enzyme is a member of a large family of flavin-specific oxidoreductases and is found in two different forms: one where the flavin adenine dinucleotide (FAD) cofactor is covalently linked to the protein and one where the cofactor is non-covalently bound to the protein. These two enzyme forms have been extensively studied in order to gain insight into the mechanism of flavin-mediated oxidation and the relationship between protein structure and enzyme redox potential. More recently the enzyme has been found to play an important role in bacterial pathogenesis and hence further studies are focused on its potential use for future development of novel antibacterial therapeutic agents. In this review the biochemical, structural, kinetic and mechanistic features of the enzyme are discussed.
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13
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Knapp JE, Pahl R, Cohen J, Nichols JC, Schulten K, Gibson QH, Srajer V, Royer WE. Ligand migration and cavities within Scapharca Dimeric HbI: studies by time-resolved crystallo-graphy, Xe binding, and computational analysis. Structure 2010; 17:1494-504. [PMID: 19913484 DOI: 10.1016/j.str.2009.09.004] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2009] [Revised: 08/25/2009] [Accepted: 09/09/2009] [Indexed: 11/19/2022]
Abstract
As in many other hemoglobins, no direct route for migration of ligands between solvent and active site is evident from crystal structures of Scapharca inaequivalvis dimeric HbI. Xenon (Xe) and organic halide binding experiments, along with computational analysis presented here, reveal protein cavities as potential ligand migration routes. Time-resolved crystallographic experiments show that photodissociated carbon monoxide (CO) docks within 5 ns at the distal pocket B site and at more remote Xe4 and Xe2 cavities. CO rebinding is not affected by the presence of dichloroethane within the major Xe4 protein cavity, demonstrating that this cavity is not on the major exit pathway. The crystal lattice has a substantial influence on ligand migration, suggesting that significant conformational rearrangements may be required for ligand exit. Taken together, these results are consistent with a distal histidine gate as one important ligand entry and exit route, despite its participation in the dimeric interface.
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Affiliation(s)
- James E Knapp
- Department of Biochemistry and Molecular Pharmacology, The University of Massachusetts Medical School, Worcester, MA 01605, USA
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Scorciapino MA, Robertazzi A, Casu M, Ruggerone P, Ceccarelli M. Heme Proteins: The Role of Solvent in the Dynamics of Gates and Portals. J Am Chem Soc 2010; 132:5156-63. [DOI: 10.1021/ja909822d] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Mariano Andrea Scorciapino
- Department of Chemical Sciences, University of Cagliari, Sardinian Laboratory for Computational Materials Science SLACS (IOM-CNR), and Department of Physics, University of Cagliari, Cittadella Universitaria, I-09042 Monserrato, Italy
| | - Arturo Robertazzi
- Department of Chemical Sciences, University of Cagliari, Sardinian Laboratory for Computational Materials Science SLACS (IOM-CNR), and Department of Physics, University of Cagliari, Cittadella Universitaria, I-09042 Monserrato, Italy
| | - Mariano Casu
- Department of Chemical Sciences, University of Cagliari, Sardinian Laboratory for Computational Materials Science SLACS (IOM-CNR), and Department of Physics, University of Cagliari, Cittadella Universitaria, I-09042 Monserrato, Italy
| | - Paolo Ruggerone
- Department of Chemical Sciences, University of Cagliari, Sardinian Laboratory for Computational Materials Science SLACS (IOM-CNR), and Department of Physics, University of Cagliari, Cittadella Universitaria, I-09042 Monserrato, Italy
| | - Matteo Ceccarelli
- Department of Chemical Sciences, University of Cagliari, Sardinian Laboratory for Computational Materials Science SLACS (IOM-CNR), and Department of Physics, University of Cagliari, Cittadella Universitaria, I-09042 Monserrato, Italy
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15
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Scorciapino MA, Robertazzi A, Casu M, Ruggerone P, Ceccarelli M. Breathing motions of a respiratory protein revealed by molecular dynamics simulations. J Am Chem Soc 2009; 131:11825-32. [PMID: 19653680 DOI: 10.1021/ja9028473] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Internal cavities, which are central to the biological functions of myoglobin, are exploited by gaseous ligands (e.g., O(2), NO, CO, etc.) to migrate inside the protein matrix. At present, it is not clear whether the ligand makes its own way inside the protein or instead the internal cavities are an intrinsic feature of myoglobin. To address this issue, standard molecular dynamics simulations were performed on horse-heart met-myoglobin with no ligand migrating inside the protein matrix. To reveal intrinsic internal pathways, the use of a statistical approach was applied to the cavity calculation, with special emphasis on the major pathway from the distal pocket to Xe1. Our study points out the remarkable dynamical behavior of Xe4, whose "breathing motions" may facilitate migration of ligands through the distal region. Additionally, our results highlight a two-way path for a ligand to diffuse through the proximal region, possibly allowing an alternative route in case Xe1 is occupied. Finally, our approach has led us to the identification of key residues, such as leucines, that may work as switches between cavities.
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Affiliation(s)
- Mariano Andrea Scorciapino
- Department of Chemical Sciences, University of Cagliari, Cittadella Universitaria, I-09042 Monserrato (Ca), Italy
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16
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Porrini M, Daskalakis V, Farantos SC, Varotsis C. Heme Cavity Dynamics of Photodissociated CO from ba3-Cytochrome c Oxidase: The Role of Ring-D Propionate. J Phys Chem B 2009; 113:12129-35. [DOI: 10.1021/jp904466n] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Massimiliano Porrini
- Institute of Electronic Structure and Laser, Foundation for Research and Technology-Hellas (FORTH), P.O. Box 1527, Vasilika Vouton, Heraklion 71110, Crete, Greece, and Department of Chemistry, University of Crete, P.O. Box 2208, Vasilika Vouton, Heraklion 71305, Crete, Greece
| | - Vangelis Daskalakis
- Institute of Electronic Structure and Laser, Foundation for Research and Technology-Hellas (FORTH), P.O. Box 1527, Vasilika Vouton, Heraklion 71110, Crete, Greece, and Department of Chemistry, University of Crete, P.O. Box 2208, Vasilika Vouton, Heraklion 71305, Crete, Greece
| | - Stavros C. Farantos
- Institute of Electronic Structure and Laser, Foundation for Research and Technology-Hellas (FORTH), P.O. Box 1527, Vasilika Vouton, Heraklion 71110, Crete, Greece, and Department of Chemistry, University of Crete, P.O. Box 2208, Vasilika Vouton, Heraklion 71305, Crete, Greece
| | - Constantinos Varotsis
- Institute of Electronic Structure and Laser, Foundation for Research and Technology-Hellas (FORTH), P.O. Box 1527, Vasilika Vouton, Heraklion 71110, Crete, Greece, and Department of Chemistry, University of Crete, P.O. Box 2208, Vasilika Vouton, Heraklion 71305, Crete, Greece
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17
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Sakurai K, Konuma T, Yagi M, Goto Y. Structural dynamics and folding of β-lactoglobulin probed by heteronuclear NMR. Biochim Biophys Acta Gen Subj 2009; 1790:527-37. [DOI: 10.1016/j.bbagen.2009.04.003] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2009] [Revised: 04/02/2009] [Accepted: 04/06/2009] [Indexed: 10/20/2022]
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18
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Mikšovská J, Horsa S, Davis MF, Franzen S. Conformational Dynamics Associated with Photodissociation of CO from Dehaloperoxidase Studied Using Photoacoustic Calorimetry. Biochemistry 2008; 47:11510-7. [DOI: 10.1021/bi8012033] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Jaroslava Mikšovská
- Department of Chemistry and Biochemistry, Florida International University, Miami, Florida 33199, and Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695
| | - Simona Horsa
- Department of Chemistry and Biochemistry, Florida International University, Miami, Florida 33199, and Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695
| | - Michael F. Davis
- Department of Chemistry and Biochemistry, Florida International University, Miami, Florida 33199, and Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695
| | - Stefan Franzen
- Department of Chemistry and Biochemistry, Florida International University, Miami, Florida 33199, and Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695
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19
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Latypov RF, Maki K, Cheng H, Luck SD, Roder H. Folding mechanism of reduced Cytochrome c: equilibrium and kinetic properties in the presence of carbon monoxide. J Mol Biol 2008; 383:437-53. [PMID: 18761351 DOI: 10.1016/j.jmb.2008.08.025] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2008] [Revised: 08/08/2008] [Accepted: 08/13/2008] [Indexed: 11/26/2022]
Abstract
Despite close structural similarity, the ferric and ferrous forms of cytochrome c differ greatly in terms of their ligand binding properties, stability, folding, and dynamics. The reduced heme iron binds diatomic ligands such as CO only under destabilizing conditions that promote weakening or disruption of native methionine-iron linkage. This makes CO a useful conformational probe for detecting partially structured states that cannot be observed in the absence of endogenous ligands. Heme absorbance, circular dichroism, and NMR were used to characterize the denaturant-induced unfolding equilibrium of ferrocytochrome c in the presence and in the absence of CO. In addition to the native state (N), which does not bind CO, and the unfolded CO complex (U-CO), a structurally distinct CO-bound form (M-CO) accumulates to high levels (approximately 75% of the population) at intermediate guanidine HCl concentrations. Comparison of the unfolding transitions for different conformational probes reveals that M-CO is a compact state containing a native-like helical core and regions of local disorder in the segment containing the native Met80 ligand and adjacent loops. Kinetic measurements of CO binding and dissociation under native, partially denaturing, and fully unfolded conditions indicate that a state M that is structurally analogous to M-CO is populated even in the absence of CO. The binding energy of the CO ligand lowers the free energy of this high-energy state to such an extent that it accumulates even under mildly denaturing equilibrium conditions. The thermodynamic and kinetic parameters obtained in this study provide a fully self-consistent description of the linked unfolding/CO binding equilibria of reduced cytochrome c.
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20
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Piubelli L, Pedotti M, Molla G, Feindler-Boeckh S, Ghisla S, Pilone MS, Pollegioni L. On the oxygen reactivity of flavoprotein oxidases: an oxygen access tunnel and gate in brevibacterium sterolicum cholesterol oxidase. J Biol Chem 2008; 283:24738-47. [PMID: 18614534 DOI: 10.1074/jbc.m802321200] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The flavoprotein cholesterol oxidase from Brevibacterium sterolicum (BCO) possesses a narrow channel that links the active center containing the flavin to the outside solvent. This channel has been proposed to serve for the access of dioxygen; it contains at its "bottom" a Glu-Arg pair (Glu-475-Arg-477) that was found by crystallographic studies to exist in two forms named "open" and "closed," which in turn was suggested to constitute a gate functioning in the control of oxygen access. Most mutations of residues that flank the channel have minor effects on the oxygen reactivity. Mutations of Glu-311, however, cause a switch in the basic kinetic mechanism of the reaction of reduced BCO with dioxygen; wild-type BCO and most mutants show a saturation behavior with increasing oxygen concentration, whereas for Glu-311 mutants a linear dependence is found that is assumed to reflect a "simple" second order process. This is taken as support for the assumption that residue Glu-311 finely tunes the Glu-475-Arg-477 pair, forming a gate that functions in modulating the access/reactivity of dioxygen.
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Affiliation(s)
- Luciano Piubelli
- Department of Biotechnology and Molecular Sciences, University of Insubria, 21100 Varese, Italy
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21
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Use of the Conjugate Peak Refinement Algorithm for Identification of Ligand‐Binding Pathways in Globins. Methods Enzymol 2008; 437:417-37. [DOI: 10.1016/s0076-6879(07)37021-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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22
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Milani M, Nardini M, Pesce A, Mastrangelo E, Bolognesi M. Hemoprotein time-resolved X-ray crystallography. IUBMB Life 2008; 60:154-8. [DOI: 10.1002/iub.23] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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23
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Investigations of vibrational coherence in the low-frequency region of ferric heme proteins. Biophys J 2007; 94:2252-68. [PMID: 18065461 DOI: 10.1529/biophysj.107.122119] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Femtosecond coherence spectroscopy is applied to a series of ferric heme protein samples. The low-frequency vibrational spectra that are revealed show dominant oscillations near 40 cm(-1). MbCN is taken as a typical example of a histidine-ligated, six-coordinate, ferric heme and a comprehensive spectroscopic analysis is carried out. The results of this analysis reveal a new heme photoproduct species, absorbing near 418 nm, which is consistent with the photolysis of the His(93) axial ligand. The photoproduct undergoes subsequent rebinding/recovery with a time constant of approximately 4 ps. The photoproduct lineshapes are consistent with a photolysis quantum yield of 75-100%, although the observation of a relatively strong six-coordinate heme coherence near 252 cm(-1) (assigned to nu(9) in the MbCN Raman spectrum) suggests that the 75% lower limit is much more likely. The phase and amplitude excitation profiles of the low-frequency mode at 40 cm(-1) suggest that this mode is strongly coupled to the MbCN photoproduct species and it is assigned to the doming mode of the transient penta-coordinated material. The absolute phase of the 40 cm(-1) mode is found to be pi/2 on the red side of 418 nm and it jumps to 3pi/2 as excitation is tuned to the blue side of 418 nm. The absolute phase of the 40 cm(-1) signal is not explained by the standard theory for resonant impulsive stimulated Raman scattering. New mechanisms that give a dominant momentum impulse to the resonant wavepacket, rather than a coordinate displacement, are discussed. The possibilities of heme iron atom recoil after photolysis, as well as ultrafast nonradiative decay, are explored as potential ways to generate the strong momentum impulse needed to understand the phase properties of the 40 cm(-1) mode.
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24
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Silkstone G, Jasaitis A, Wilson MT, Vos MH. Ligand Dynamics in an Electron Transfer Protein. J Biol Chem 2007; 282:1638-49. [PMID: 17114183 DOI: 10.1074/jbc.m605760200] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Substitution of the heme coordination residue Met-80 of the electron transport protein yeast iso-1-cytochrome c allows external ligands like CO to bind and thus increase the effective redox potential. This mutation, in principle, turns the protein into a quasi-native photoactivable electron donor. We have studied the kinetic and spectral characteristics of geminate recombination of heme and CO in a series of single M80X (X = Ala, Ser, Asp, Arg) mutants, using femtosecond transient absorption spectroscopy. In these proteins, all geminate recombination occurs on the picosecond and early nanosecond time scale, in a multiphasic manner, in which heme relaxation takes place on the same time scale. The extent of geminate recombination varies from >99% (Ala, Ser) to approximately 70% (Arg), the latter value being in principle low enough for electron injection studies. The rates and extent of the CO geminate recombination phases are much higher than in functional ligand-binding proteins like myoglobin, presumably reflecting the rigid and hydrophobic properties of the heme environment, which are optimized for electron transfer. Thus, the dynamics of CO recombination in cytochrome c are a tool for studying the heme pocket, in a similar way as NO in myoglobin. We discuss the differences in the CO kinetics between the mutants in terms of the properties of the heme environment and strategies to enhance the CO escape yield. Experiments on double mutants in which Phe-82 is replaced by Asp or Gly as well as the M80D substitution indicate that such steric changes substantially increase the motional freedom-dissociated CO.
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Affiliation(s)
- Gary Silkstone
- Department of Biological Sciences, Wivenhoe Park, University of Essex, Colchester CO4 3SQ, United Kingdom
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25
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Rong L, Zhang Z, Lin Y, Xie Y, Pang D. Direct Electrochemistry and Electrocatalysis of Myoglobin Entrapped in Konjac Glucomannan Films. CHINESE JOURNAL OF ANALYTICAL CHEMISTRY 2006. [DOI: 10.1016/s1872-2040(07)60018-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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26
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Fukuma H, Nakashima K, Ozaki Y, Noda I. Two-dimensional fluorescence correlation spectroscopy IV: resolution of fluorescence of tryptophan residues in alcohol dehydrogenase and lysozyme. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2006; 65:517-22. [PMID: 16520086 DOI: 10.1016/j.saa.2005.12.012] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2005] [Revised: 07/17/2005] [Accepted: 12/02/2005] [Indexed: 05/07/2023]
Abstract
Generalized two-dimensional (2D) fluorescence correlation spectroscopy has been used to resolve the fluorescence spectra of two tryptophan (Trp) residues in alcohol dehydrogenase and lysozyme. In each protein, one Trp residue is buried in a hydrophobic domain of the protein matrix and the other Trp residue is located at a hydrophilic domain close to the protein-water interface. Fluorescence quenching by iodide ion, a hydrophilic quencher, was employed as a perturbation to induce the intensity change in the spectra. The Trp residue which is located at the hydrophilic domain is effectively quenched by the quencher, while the Trp residue located at the hydrophobic domain is protected from the quenching. Therefore, the fluorescence of these two Trp residues have a different sensitivity to the quenching, showing a different response to the concentration of the quencher. Fluorescence spectra of the two Trp residues in alcohol dehydrogenase, which are heavily overlapped in conventional one-dimensional spectra, have been successfully resolved by the 2D correlation technique. From the asynchronous correlation map, it was revealed that the quenching of Trp located at the hydrophobic part was brought about after that of Trp located at the hydrophilic part. In contrast, the fluorescence spectra of the two Trp residues could not be resolved after the alcohol dehydrogenase was denatured with guanidine hydrochloride. These results are consistent with the well-known structure of alcohol dehydrogenase. Furthermore, it was elucidated that the present 2D analysis is not interfered by Raman bands of the solvent, which sometimes bring difficulty into the conventional fluorescence analysis. Fluorescence spectra of the Trp residues in lysozyme could not be resolved by the 2D correlation technique. The differences between the two proteins are attributed to the fact that the Trp residue in the hydrophobic site of lysozyme is not sufficiently protected from the quenching.
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Affiliation(s)
- Hiroaki Fukuma
- Department of Chemistry, Faculty of Science and Engineering, Saga University, Saga 840-8502, Japan
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27
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Nutt DR, Meuwly M. Studying reactive processes with classical dynamics: rebinding dynamics in MbNO. Biophys J 2005; 90:1191-201. [PMID: 16326913 PMCID: PMC1367270 DOI: 10.1529/biophysj.105.071522] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
A new surface-crossing algorithm suitable for describing bond-breaking and bond-forming processes in molecular dynamics simulations is presented. The method is formulated for two intersecting potential energy manifolds which dissociate to different adiabatic states. During simulations, crossings are detected by monitoring an energy criterion. If fulfilled, the two manifolds are mixed over a finite number of time steps, after which the system is propagated on the second adiabat and the crossing is carried out with probability one. The algorithm is extensively tested (almost 0.5 mus of total simulation time) for the rebinding of NO to myoglobin. The unbound surface (Fe...NO) is represented using a standard force field, whereas the bound surface (Fe-NO) is described by an ab initio potential energy surface. The rebinding is found to be nonexponential in time, in agreement with experimental studies, and can be described using two time constants. Depending on the asymptotic energy separation between the manifolds, the short rebinding timescale is between 1 and 9 ps, whereas the longer timescale is about an order of magnitude larger. NO molecules which do not rebind within 1 ns are typically found in the Xenon-4 pocket, indicating the high affinity of NO to this region in the protein.
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Affiliation(s)
- David R Nutt
- Department of Chemistry, University of Basel, 4056 Basel, Switzerland
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28
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Observation of sub-100ps conformational changes in photolyzed carbonmonoxy-myoglobin probed by time-resolved circular dichroism. Chem Phys Lett 2005. [DOI: 10.1016/j.cplett.2005.09.022] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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29
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Cordone L, Cottone G, Giuffrida S, Palazzo G, Venturoli G, Viappiani C. Internal dynamics and protein–matrix coupling in trehalose-coated proteins. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2005; 1749:252-81. [PMID: 15886079 DOI: 10.1016/j.bbapap.2005.03.004] [Citation(s) in RCA: 103] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/12/2004] [Revised: 03/04/2005] [Accepted: 03/04/2005] [Indexed: 11/23/2022]
Abstract
We review recent studies on the role played by non-liquid, water-containing matrices on the dynamics and structure of embedded proteins. Two proteins were studied, in water-trehalose matrices: a water-soluble protein (carboxy derivative of horse heart myoglobin) and a membrane protein (reaction centre from Rhodobacter sphaeroides). Several experimental techniques were used: Mossbauer spectroscopy, elastic neutron scattering, FTIR spectroscopy, CO recombination after flash photolysis in carboxy-myoglobin, kinetic optical absorption spectroscopy following pulsed and continuous photoexcitation in Q(B) containing or Q(B) deprived reaction centre from R. sphaeroides. Experimental results, together with the outcome of molecular dynamics simulations, concurred to give a picture of how water-containing matrices control the internal dynamics of the embedded proteins. This occurs, in particular, via the formation of hydrogen bond networks that anchor the protein surface to the surrounding matrix, whose stiffness increases by lowering the sample water content. In the conclusion section, we also briefly speculate on how the protein-matrix interactions observed in our samples may shed light on the protein-solvent coupling also in liquid aqueous solutions.
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Affiliation(s)
- Lorenzo Cordone
- Dipartimento di Scienze Fisiche ed Astronomiche, Università di Palermo, Italy.
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30
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Nagy AM, Raicu V, Miller RJD. Nonlinear optical studies of heme protein dynamics: Implications for proteins as hybrid states of matter. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2005; 1749:148-72. [PMID: 15927874 DOI: 10.1016/j.bbapap.2005.02.005] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2004] [Revised: 02/03/2005] [Accepted: 02/15/2005] [Indexed: 10/25/2022]
Abstract
Protein structure is fundamentally related to function. However, static structures alone are insufficient to understand how a protein works. Dynamics play an equally important role. Given that proteins are highly associated aperiodic systems, it may be expected that protein dynamics would follow glass-like dynamics. However, protein functions occur on time scales orders of magnitude faster than the time scales typically associated with glassy systems. It is becoming clear that the reaction forces driving functions do not sample entirely the large number of configurations available to a protein but are highly directed along an optimized pathway. Could there be any correlation between specific topological features in protein structures and dynamics that leads to strongly correlated atomic displacements in the dynamical response to a perturbation? This review will try to provide an answer by focusing upon recent nonlinear optical studies with the aim of directly observing functionally important protein motions over the entire dynamic range of the protein response function. The specific system chosen is photoinduced dynamics of ligand dissociation at the active site in heme proteins, with myoglobin serving as the simplest model system. The energetics and nuclear motions from the very earliest events involved in bond breaking on the femtosecond time scale all the way out to ligand escape and bimolecular rebinding on the microsecond and millisecond time scale have been mapped out. The picture that is emerging is that the system consists of strongly coupled motions from the very instant the bond breaks at the active site that cascade into low frequency collective modes specific to the protein structure. It is this coupling that imparts the ability of a protein to function on time scales more commensurate with liquids while simultaneously conserving structural integrity akin to solids.
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Affiliation(s)
- A M Nagy
- Department of Chemistry, University of Toronto, Ontario, Canada
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31
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Regis WCB, Fattori J, Santoro MM, Jamin M, Ramos CHI. On the difference in stability between horse and sperm whale myoglobins. Arch Biochem Biophys 2005; 436:168-77. [PMID: 15752722 DOI: 10.1016/j.abb.2005.01.016] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2004] [Revised: 01/19/2005] [Indexed: 11/16/2022]
Abstract
The work in the literature on apomyoglobin is almost equally divided between horse and sperm whale myoglobins. The two proteins share high homology, show similar folding behavior, and it is often assumed that all folding phenomena found with one protein will also be found with the other. We report data at equilibrium showing that horse myoglobin was 2.1 kcal/mol less stable than sperm whale myoglobin at pH 5.0, and aggregated at high concentrations as measured by gel filtration and analytical ultracentrifugation experiments. The higher stability of sperm whale myoglobin was identified for both apo and holo forms, and was independent of pH from 5 to 8 and of the presence of sodium chloride. We also show that the substitution of sperm whale myoglobin residues Ala15 and Ala74 to Gly, the residues found at positions 15 and 74 in horse myoglobin, decreased the stability by 1.0 kcal/mol, indicating that helix propensity is an important component of the explanation for the difference in stability between the two proteins.
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Affiliation(s)
- Wiliam C B Regis
- Centro de Biologia Molecular Estrutural, Laboratório Nacional de Luz Síncrotron, P.O. Box 6192, ZIP Code 13084971, Campinas SP, Brazil
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32
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Zheng Q, Liu Z, Cai R. Determination of myoglobin based on its enzymatic activity by stopped-flow spectrophotometry. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2005; 61:1035-1038. [PMID: 15741099 DOI: 10.1016/j.saa.2004.06.010] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/05/2004] [Revised: 06/08/2004] [Accepted: 06/08/2004] [Indexed: 05/24/2023]
Abstract
A new method has been developed for the determination of myoglobin (Mb) based on its enzymatic activity for the oxidation of o-phenylenediamine (OPDA) with hydrogen peroxide. Stopped-flow spectrophotometry was used to study the kinetic behavior of the oxidation reaction. The catalytic activity of Mb was compared to other three kinds of catalyst. The time dependent absorbance of the reaction product, 2,3-diamimophenazine (DAPN), at a wavelength of 426 nm was recorded. The initial reaction rate obtained at 40 degrees C was found to be proportional to the concentration of Mb in the range of 1.0 x 10(-6) to 4.0 x 10(-9)mol L(-1). The detection limit of Mb was found to be 9.93 x 10(-10)mol L(-1). The relative standard deviations were within 5% for the determination of different concentrations of Mb. Excess of bovine serum albumin (BSA), Ca(II), Mg(II), Cu(II), glucose, caffeine, lactose and uric acid did not interfere.
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Affiliation(s)
- Qi Zheng
- Department of Chemistry, Wuhan University, Wuhan 430072, PR China.
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33
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Phosphorescence of individual horseradish peroxidases proteins having a modified heme group. Chem Phys Lett 2005. [DOI: 10.1016/j.cplett.2004.10.133] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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34
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Tetreau C, Mouawad L, Murail S, Duchambon P, Blouquit Y, Lavalette D. Disentangling ligand migration and heme pocket relaxation in cytochrome P450cam. Biophys J 2004; 88:1250-63. [PMID: 15489303 PMCID: PMC1305127 DOI: 10.1529/biophysj.104.050104] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
In this work we show that ligand migration and active site conformational relaxation can occur independently of each other in hemoproteins. The complicated kinetics of carbon monoxide rebinding with cytochrome P450cam display up to five distinct processes between 77 K and 300 K. They were disentangled by using a combination of three approaches: 1), the competition of the ligand with xenon for the occupation of internal protein cavities; 2), the modulation of the amount of distal steric hindrance within the heme pocket by varying the nature of the substrate; and 3), molecular mechanics calculations to support the proposed heme-substrate relaxation mechanism and to seek internal cavities. In cytochrome P450cam, active site conformational relaxation results from the displacement of the substrate toward the heme center upon photodissociation of the ligand. It is responsible for the long, puzzling bimodal nature of the rebinding kinetics observed down to 77 K. The relaxation rate is strongly substrate-dependent. Ligand migration is slower and is observed only above 135 K. Migration and return rates are independent of the substrate.
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Affiliation(s)
- Catherine Tetreau
- Biophysique Moléculaire, Institut Curie, Centre Universitaire, Orsay, France
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35
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Liu HH, Tian ZQ, Lu ZX, Zhang ZL, Zhang M, Pang DW. Direct electrochemistry and electrocatalysis of heme-proteins entrapped in agarose hydrogel films. Biosens Bioelectron 2004; 20:294-304. [PMID: 15308234 DOI: 10.1016/j.bios.2004.01.015] [Citation(s) in RCA: 152] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2003] [Revised: 01/26/2004] [Accepted: 01/26/2004] [Indexed: 11/16/2022]
Abstract
Three heme-proteins, including myoglobin (Mb), hemoglobin (Hb) and horseradish peroxidase (HRP), were immobilized on edge-plane pyrolytic graphite (EPG) electrodes by agarose hydrogel. The proteins entrapped in the agarose film undergo fast direct electron transfer reactions, corresponding to FeIII = e- --> FeII. The formal potential (E degrees'), the apparent coverage (Gamma), the electron transfer coefficient (alpha) and the apparent electron transfer rate constant (ks) were calculated by integrating cyclic voltammograms or performing nonlinear regression analysis of square wave voltammetric (SWV) experimental data. The E degrees's are linearly dependent on solution pH (redox Bohr effect), indicating that the electron transfer was proton-coupled. Ultraviolet visible (UV-Vis) and reflection-absorption infrared (RAIR) spectra suggest that the conformation of proteins in the agarose film are little different from that proteins alone, and the conformation changes reversibly in the range of pH 3.0-10.0. Atomic force microscopy (AFM) images of the agarose film indicate a stable and crystal-like structure formed possibly due to the synergistic interaction of hydrogen bonding between N,N-dimethylformamide (DMF), agarose hydrogel and heme-proteins. This suggests a strong interaction between the heme-proteins and the agarose hydrogel. DMF plays an important role in immobilizing proteins and enhancing electron transfer between proteins and electrodes. The mechanisms for catalytic reduction of hydrogen peroxide and nitric oxide (NO) by proteins entrapped in agarose hydrogel were also explored.
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Affiliation(s)
- Hui-Hong Liu
- Department of Chemistry, Wuhan University, Wuhan 430072, China
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36
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Tetreau C, Blouquit Y, Novikov E, Quiniou E, Lavalette D. Competition with xenon elicits ligand migration and escape pathways in myoglobin. Biophys J 2004; 86:435-47. [PMID: 14695286 PMCID: PMC1303809 DOI: 10.1016/s0006-3495(04)74120-x] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Evidence for ligand migration toward the xenon-binding cavities in myoglobin comes from a number of laser photolysis studies of MbO2 including mutants and from cryo- and time-resolved crystallography of MbCO. To explore ligand migration in greater detail, we investigated the rebinding kinetics of both MbO2 and MbCO under a xenon partial pressure ranging from 1 to 16 atm over the temperature range (293-77 K). Below 180 K xenon affects to a significant, but minor, extent the thermodynamic parameters for rebinding from the primary docking site in each Mb taxonomic substate. Above 200 K the ligand migrates to the proximal Xe1 site but when the latter is occupied by xenon a new kinetic process appears. It is attributed to rebinding from transient docking sites located on the path between the primary and the secondary docking site of both ligands. Ligand escape exhibits a more complicated pattern than expected. At room temperature O2 and CO escape appears to take place exclusively from the primary site. In contrast, at T approximately 250 K, roughly 50% of the CO molecules that have escaped from the protein originate from the Xe1 secondary site.
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Affiliation(s)
- Catherine Tetreau
- Institut Curie-Recherche (INSERM U350), Centre Universitaire, 91405 Orsay, France
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37
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Abstract
The biomolecular conformational changes often associated with allostery are, by definition, dynamic processes. Recent publications have disclosed the role of pre-existing equilibria of conformational substates in this process. In addition, the role of dynamics as an entropic carrier of free energy of allostery has been investigated. Recent work thus shows that dynamics is pivotal to allostery, and that it constitutes much more than just the move from the 'T'-state to the 'R'-state. Emerging computational studies have described the actual pathways of allosteric change.
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Affiliation(s)
- Dorothee Kern
- Department of Biochemistry, Brandeis University, 415 South Street, Waltham, MA 02454-9110, USA.
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38
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Nutt DR, Meuwly M. Theoretical investigation of infrared spectra and pocket dynamics of photodissociated carbonmonoxy myoglobin. Biophys J 2004; 85:3612-23. [PMID: 14645054 PMCID: PMC1303666 DOI: 10.1016/s0006-3495(03)74779-1] [Citation(s) in RCA: 92] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
Molecular dynamics simulations of the photodissociated state of carbonmonoxy myoglobin (MbCO) are presented using a fluctuating charge model for CO. A new three-point charge model is fitted to high-level ab initio calculations of the dipole and quadrupole moment functions taken from the literature. The infrared spectrum of the CO molecule in the heme pocket is calculated using the dipole moment time autocorrelation function and shows good agreement with experiment. In particular, the new model reproduces the experimentally observed splitting of the CO absorption spectrum. The splitting of 3-7 cm(-1) (compared to the experimental value of 10 cm(-1)) can be directly attributed to the two possible orientations of CO within the docking site at the edge of the distal heme pocket (the B states), as previously suggested on the basis of experimental femtosecond time-resolved infrared studies. Further information on the time evolution of the position and orientation of the CO molecule is obtained and analyzed. The calculated difference in the free energy between the two possible orientations (Fe...CO and Fe...OC) is 0.3 kcal mol(-1) and agrees well with the experimentally estimated value of 0.29 kcal mol(-1). A comparison of the new fluctuating charge model with an established fixed charge model reveals some differences that may be critical for the correct prediction of the infrared spectrum and energy barriers. The photodissociation of CO from the myoglobin mutant L29F using the new model shows rapid escape of CO from the distal heme pocket, in good agreement with recent experimental data. The effect of the protein environment on the multipole moments of the CO ligand is investigated and taken into account in a refined model. Molecular dynamics simulations with this refined model are in agreement with the calculations based on the gas-phase model. However, it is demonstrated that even small changes in the electrostatics of CO alter the details of the dynamics.
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Affiliation(s)
- David R Nutt
- Department of Chemistry, University of Basel, CH-4056 Basel, Switzerland
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Nakashima K, Yuda K, Ozaki Y, Noda I. Two-dimensional fluorescence correlation spectroscopy: resolution of fluorescence of tryptophan residues in horse heart myoglobin. APPLIED SPECTROSCOPY 2003; 57:1381-1385. [PMID: 14658152 DOI: 10.1366/000370203322554545] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Generalized two-dimensional (2D) fluorescence correlation spectroscopy has been used to resolve fluorescence of two tryptophan (Trp) residues in horse heart myoglobin. Fluorescence quenching is employed as a perturbation mode for causing intensity changes in the fluorescence (quenching perturbation). Two kinds of quenchers, iodide ion and acrylamide, are used for inducing fluorescence intensity change. This technique works because the Trp residue located at the 7th position (W7) is known to be easily accessible to the quencher, whereas that located at the 14th position (W14) is not. By this technique, the fluorescence spectra of the two Trp residues were clearly resolved. From asynchronous maps, it was also shown that the quenching of W7 fluorescence is brought about prior to the quenching of W14 fluorescence. This result is consistent with the structure of horse heart myoglobin that was proposed earlier. Furthermore, it was elucidated that the present 2D analysis is not interfered with by Raman bands of the solvents, which sometimes brings difficulty into conventional fluorescence analysis.
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Affiliation(s)
- Kenichi Nakashima
- Department of Chemistry, Faculty of Science and Engineering, Saga University, Saga 840-8502, Japan.
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40
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Khajehpour M, Rietveld I, Vinogradov S, Prabhu NV, Sharp KA, Vanderkooi JM. Accessibility of oxygen with respect to the heme pocket in horseradish peroxidase. Proteins 2003; 53:656-66. [PMID: 14579357 DOI: 10.1002/prot.10475] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Oxygen and other molecules of similar size take part in a variety of protein reactions. Therefore, it is critical to understand how these small molecules penetrate the protein matrix. The protein system studied in this case is horseradish peroxidase (HRP). We have converted the native HRP into a phosphorescent analog by replacing the heme prosthetic group by Pd-mesoporphyrin. Oxygen readily quenches the phosphorescence of Pd porphyrins, and this can be used to characterize oxygen diffusion through the protein matrix. Our measurements indicate that solvent viscosity and pH modulate the accessibility of the heme pocket relative to small molecules. The binding of the substrate benzohydroxamic acid (BHA) to the protein drastically impedes oxygen access to the heme pocket. These results indicate that, first, the penetration of small molecules through the protein matrix is a function of protein dynamics, and second, there are specific pathways for the diffusion of these molecules. The effect of substrate and pH on protein dynamics has been investigated with the use of molecular dynamics calculations. We demonstrate that the model of a "fluctuating entry point," as suggested by Zwanzig (J Chem Phys 1992;97:3587-3589), properly describes the diffusion of oxygen through the protein matrix.
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Affiliation(s)
- Mazdak Khajehpour
- Department of Biochemistry and Biophysics, School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
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Samuni U, Dantsker D, Ray A, Wittenberg JB, Wittenberg BA, Dewilde S, Moens L, Ouellet Y, Guertin M, Friedman JM. Kinetic modulation in carbonmonoxy derivatives of truncated hemoglobins: the role of distal heme pocket residues and extended apolar tunnel. J Biol Chem 2003; 278:27241-50. [PMID: 12736253 DOI: 10.1074/jbc.m212634200] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Truncated hemoglobins (trHbs), are a distinct and newly characterized class of small myoglobin-like proteins that are widely distributed in bacteria, unicellular eukaryotes, and higher plants. Notable and distinctive features associated with trHbs include a hydrogen-bonding network within the distal heme pocket and a long apolar tunnel linking the external solvent to the distal heme pocket. The present work compares the geminate and solvent phase rebinding kinetics from two trHbs, one from the ciliated protozoan Paramecium caudatum (P-trHb) and the other from the green alga Chlamydomonas eugametos (C-trHb). Unusual kinetic patterns are observed including indications of ultrafast (picosecond) geminate rebinding of CO to C-trHb, very fast solvent phase rebinding of CO for both trHbs, time-dependent biphasic CO rebinding kinetics for P-trHb at low CO partial pressures, and for P-trHb, an increase in the geminate yield from a few percent to nearly 100% under high viscosity conditions. Species-specific differences in both the 8-ns photodissociation quantum yield and the rebinding kinetics, point to a pivotal functional role for the E11 residue. The response of the rebinding kinetics to temperature, ligand concentration, and viscosity (glycerol, trehalose) and the viscosity-dependent changes in the resonance Raman spectrum of the liganded photoproduct, together implicate both the apolar tunnel and the static and dynamic properties of the hydrogen-bonding network within the distal heme pocket in generating the unusual kinetic patterns observed for these trHbs.
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Affiliation(s)
- Uri Samuni
- Department of Physiology and Biophysics, Albert Einstein College of Medicine, Bronx, New York 10461, USA
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Ciaccio C, Rosati A, De Sanctis G, Sinibaldi F, Marini S, Santucci R, Ascenzi P, Welinder KG, Coletta M. Relationships of ligand binding, redox properties, and protonation in Coprinus cinereus peroxidase. J Biol Chem 2003; 278:18730-7. [PMID: 12621034 DOI: 10.1074/jbc.m212034200] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The pH dependence of the redox potentials and kinetics for CO association and dissociation was determined between pH 3.0 and 13.0 at 25 degrees C for the wild-type Coprinus cinereus fungal peroxidase and for a site-directed mutant in which Asp245, which is H-bonded to N delta of the imidazole of the proximal His183, was substituted with Asn. The determination of these functional properties allowed this information to be merged in a self-consistent fashion and to formulate for the first time a complete scheme employing the minimum number of groups required to describe the whole proton-linked behavior of both redox and ligand binding properties. The overall pH dependence can be accounted for by four redox- and ligand-linked groups. The proximal H-bond, which is strictly conserved in all peroxidases, will still be present in the site-specific mutant, but will no longer have an ionic character, and this event will bring about an alteration of redox equilibria and CO binding kinetics, envisaging a relevant role played by this H-bond also in modulating redox properties and ligand binding equilibria.
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Affiliation(s)
- Chiara Ciaccio
- Department of Experimental Medicine and Biochemical Sciences, Università di Roma Tor Vergata, Via Montpellier 1, I-00133 Roma, Italy
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Samuni U, Dantsker D, Khan I, Friedman AJ, Peterson E, Friedman JM. Spectroscopically and kinetically distinct conformational populations of sol-gel-encapsulated carbonmonoxy myoglobin. A comparison with hemoglobin. J Biol Chem 2002; 277:25783-90. [PMID: 11976324 DOI: 10.1074/jbc.m200301200] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We have used sol-gel encapsulation protocols to trap kinetically and spectroscopically distinct conformational populations of native horse carbonmonoxy myoglobin. The method allows for direct comparison of functional and spectroscopic properties of equilibrium and non-equilibrium populations under the same temperature and viscosity conditions. The results implicate tertiary structure changes that include the proximal heme environment in the mechanism for population-specific differences in the observed rebinding kinetics. Differences in the resonance Raman frequency of nu(Fe-His), the iron-proximal histidine stretching mode, are attributed to differences in the positioning of the F helix. For myoglobin, the degree of separation between the F helix and the heme is assigned as the conformational coordinate that modulates both this frequency and the innermost barrier controlling CO rebinding. A comparison with the behavior of encapsulated derivatives of human adult hemoglobin indicates that these CO binding-induced conformational changes are qualitatively similar to the tertiary changes that occur within both the R and T quaternary states. Protein-specific differences in the time scale for the proposed F helix relaxation are attributed to variations in the intra-helical hydrogen bonding patterns that help stabilize the position of the F helix.
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Affiliation(s)
- Uri Samuni
- Department of Physiology and Biophysics, Albert Einstein College of Medicine, Bronx, New York 10461, USA
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Silkstone G, Stanway G, Brzezinski P, Wilson MT. Production and characterisation of Met80X mutants of yeast iso-1-cytochrome c: spectral, photochemical and binding studies on the ferrous derivatives. Biophys Chem 2002; 98:65-77. [PMID: 12128190 DOI: 10.1016/s0301-4622(02)00085-6] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The iron ligand, Met80, of yeast iso-1-cytochrome c has been mutated to residues that are unable to bind to the iron. The resultant proteins, Met80Ala, Ser, Asp, Glu, have been expressed and purified. All mutant proteins exhibit well defined pH dependent spectral transitions that report the binding, at high pH, of an intrinsic ligand (probably the nitrogen of an epsilon-NH(2) of a lysine) that drives the heme low-spin. The pK values are mutant dependent. All the mutant proteins bind extrinsic ligands, such as CO, in their ferrous states and we report the apparent quantum yield (phi) for CO photo-dissociation. The values of phi range from 0.004 for Met80Ala to 0.04 for Met80Asp. We also report values for the rate constant for binding the intrinsic lysine residue. The values for this constant, for phi and for the pK values are discussed in terms of the rigidity of the cytochrome structure. We also show that the mutant proteins bind with high affinity to cytochrome c oxidase, both in the ferric and ferrous states. The potential of these proteins to act as light activated electron donors for the study of electron transfer is discussed.
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Affiliation(s)
- Gary Silkstone
- Department of Biological Sciences, University of Essex, Wivenhoe Park, Colchester CO4 3SQ, UK
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Abstract
Protein dynamics is crucial for protein function. Proteins in living systems are not isolated, but operate in networks and in a carefully regulated environment. Understanding the external control of protein dynamics is consequently important. Hydration and solvent viscosity are among the salient properties of the environment. Dehydrated proteins and proteins in a rigid environment do not function properly. It is consequently important to understand the effect of hydration and solvent viscosity in detail. We discuss experiments that separate the two effects. These experiments have predominantly been performed with wild-type horse and sperm whale myoglobin, using the binding of carbon monoxide over a broad range of temperatures as a tool. The experiments demonstrate that data taken only in the physiological temperature range are not sufficient to understand the effect of hydration and solvent on protein relaxation and function. While the actual data come from myoglobin, it is expected that the results apply to most or all globular proteins.
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Affiliation(s)
- Hans Frauenfelder
- Center for Non-linear Studies, MS B258, Los Alamos National Laboratory, Los Alamos, NM 87545, USA
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Grunwaldt G, Haebel S, Spitz C, Steup M, Menzel R. Multiple binding sites of fluorescein isothiocyanate moieties on myoglobin: photophysical heterogeneity as revealed by ground- and excited-state spectroscopy. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY. B, BIOLOGY 2002; 67:177-86. [PMID: 12167317 DOI: 10.1016/s1011-1344(02)00323-8] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Fluorescein isothiocyanate (FITC)-myoglobin conjugates were synthesized with a binding stoichiometry of one to three fluorophores per protein. FITC binding sites were determined by matrix-assisted laser desorption-ionization time-of-flight mass spectrometry (MALDI-TOF MS). Five lysine residues and the N-terminal amino group were identified as preferential binding sites. The ground and excited-state absorption spectra and the fluorescence decay of the conjugates in the native and denatured state of the carrier protein were analyzed. For comparison, unbound FITC and FITC covalently bound to a polysaccharide (dextran) were studied. For FITC, FITC-dextran and the FITC-myoglobin conjugates, only one FITC absorption peak was obtained in the ground state spectrum. Similarly, the excited state absorption (ESA) spectra of unbound FITC and of FITC-dextran showed only one single maximum whereas two maxima were detected for the native FITC-myoglobin conjugates. One of these sub-bands disappeared following urea treatment of the conjugate. We conclude that ESA measurements of extrinsic fluorophores on proteins can be used to monitor different micro-environments of the fluorophore and to distinguish between different conformational states of the labeled protein. This method can be a useful tool for analysing coexisting protein conformations.
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Affiliation(s)
- Gisela Grunwaldt
- Institute of Biochemistry and Biology, Plant Physiology, University of Potsdam, Karl-Liebknecht-Strasse 24-25, Haus 20, Golm, Germany.
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Abstract
Freeze-trapping reaction intermediates in macromolecular crystals is now a proven technique for obtaining their high-resolution structures by X-ray crystallography. The structural study of metalloprotein mechanisms has spearheaded this work, mainly because of the increased availability of single-crystal UV/visible spectrophotometry that enables reaction monitoring in the crystalline state. In particular, through formation of the frozen glass state, the stabilization of intermediates involving dissolved gases has yielded some of the most spectacular results. Metalloprotein systems still dominate this field, and the most recent successes, along with the accompanying advances in methodology, are presented.
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Affiliation(s)
- Carrie M Wilmot
- Department of Biochemistry, Molecular Biology & Biophysics, University of Minnesota, 6-155 Jackson Hall, 321 Church Street SE, Minneapolis, Minnnesota 55455, USA
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Affiliation(s)
- Jens K S Møller
- Food Chemistry, Department of Dairy and Food Science, Royal Veterinary and Agricultural University, Rolighedsvej 30, DK-1958 Frederiksberg C., Denmark
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49
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Dantsker D, Samuni U, Friedman AJ, Yang M, Ray A, Friedman JM. Geminate rebinding in trehalose-glass embedded myoglobins reveals residue-specific control of intramolecular trajectories. J Mol Biol 2002; 315:239-51. [PMID: 11779242 DOI: 10.1006/jmbi.2001.5218] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
It is becoming increasingly apparent that hydrophobic cavities (also referred to as xenon cavities) within proteins have significant functional implications. The potential functional role of these cavities in modulating the internal dynamics of carbon monoxide in myoglobin (Mb) is explored in the present study by using glassy matrices derived from trehalose to limit protein dynamics and to eliminate ligand exchange between the solvent and the protein. By varying the temperature (-15 to 65 degrees C) and humidity for samples of carbonmonoxy myoglobin embedded in trehalose-glass, it is possible to observe a hierarchy of distinct geminate recombination phases that extend from nanosecond to almost seconds that can be directly associated with rebinding from specific hydrophobic cavities. The use of mutant forms of Mb reveals the role of key residues in modulating ligand access between these cavities and the distal hemepocket.
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Affiliation(s)
- David Dantsker
- Department of Physiology and Biophysics, Albert Einstein College of Medicine, Bronx 10461, USA
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Abstract
Biological molecules are mesoscopic systems that bridge the quantum and classical worlds. At the single molecule level, there are often more than 1 × 104 degrees of freedom that are involved in protein-mediated processes. These molecules are sufficiently large that the bath coordinate convolved to the reaction at an active site is defined by the surrounding protein tertiary structure. In this context, the very interatomic forces that determine the active protein structures create a strongly associated system. Thus, the bath fluctuations leading to reactive crossings involve highly hindered motions within a myriad of local minima that would act to cast the reaction dynamics into the high viscosity limit appropriate to glasses. However, the time scales observed for biological events are orders of magnitude too fast to meet this anticipated categorization. In this context, the apparent deterministic nature of biological processes represents an enormous challenge to our understanding of chemical processes. Somehow Nature has discovered a molecular scaffolding that enables minute amounts of energy to be efficiently channeled to perform biological functions without becoming entrapped in local minima. Clearly, energy derived from chemical processes is highly directed in biological systems. To understand this problem, we must first understand how energy is redistributed among the different degrees of freedom and fully characterize the protein relaxation processes along representative reaction coordinates in relation to these dissipative processes. This paper discusses the development of new nonlinear spectroscopic methods that have enabled interferometric sensitivity to protein motions on femtosecond time scales appropriate to the very fastest motions (i.e., bond breaking or the molecular "Big Bang") out to the slowest relaxation steps. This work has led to the Collective Mode Coupling Model as an explanation of the required reduced dimensionality in biological systems. Within this model, the largest coupling coefficients of the reaction coordinate are to the damped inertial collective modes of the protein defined by the strongly correlated secondary structures. These modes act to guide the reaction along the correct seam(s) in an otherwise highly complex potential energy surface. The mechanism by which biological molecules have been able to harness chemical energy over meso-length scales represents the first step towards higher levels of organization. The new insight afforded by the collective mode mechanism may prove important in understanding this larger issue of scaling in biological systems.Key words: biodynamics, energy transduction, ultrafast spectroscopy, nonlinear spectroscopy, primary processes in biology.
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