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Botticelli S, Chiaraluce R, Consalvi V, La Penna G, Pasquo A, Petrosino M, Proux O, Rossi GC, Stellato F, Morante S. The role of Zn ions in the interaction between SARS-CoV-2 orf7a protein and BST2/tetherin. Eur Phys J Plus 2023; 138:216. [PMID: 36911363 PMCID: PMC9992918 DOI: 10.1140/epjp/s13360-023-03731-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/23/2022] [Accepted: 01/22/2023] [Indexed: 06/18/2023]
Abstract
In this paper, we provide evidence that Zn 2 + ions play a role in the SARS-CoV-2 virus strategy to escape the immune response mediated by the BST2-tetherin host protein. This conclusion is based on sequence analysis and molecular dynamics simulations as well as X-ray absorption experiments [1].
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Affiliation(s)
- S. Botticelli
- Università di Roma “Tor Vergata” and INFN, Sezione di Roma 2 - Via della Ricerca Scientifica 1, 00133 Rome, Italy
| | - R. Chiaraluce
- Dipartimento di Biochimica, Sapienza Universitá di Roma, Piazzale Aldo Moro 5, 00185 Rome, Italy
| | - V. Consalvi
- Dipartimento di Biochimica, Sapienza Universitá di Roma, Piazzale Aldo Moro 5, 00185 Rome, Italy
| | - G. La Penna
- CNR, Institute for Chemistry of Organometallic Compounds, 50019 Sesto Fiorentino, Italy
| | - A. Pasquo
- ENEA CR Frascati, Diagnostics and Metrology Laboratory FSN-TECFIS-DIM, Via E. Fermi, 45, 00044 Frascati, Italy
| | - M. Petrosino
- Dipartimento di Biochimica, Sapienza Universitá di Roma, Piazzale Aldo Moro 5, 00185 Rome, Italy
| | - O. Proux
- Observatoire des Sciences de l’Univers de Grenoble, UMS 832 CNRS, Université Grenoble Alpes, 38041 Grenoble, France
| | - G. C. Rossi
- Università di Roma “Tor Vergata” and INFN, Sezione di Roma 2 - Via della Ricerca Scientifica 1, 00133 Rome, Italy
- Centro Fermi - Museo Storico della Fisica e Centro Studi e Ricerche Enrico Fermi, Via Panisperna 89a, 00184 Roma, Italy
| | - F. Stellato
- Università di Roma “Tor Vergata” and INFN, Sezione di Roma 2 - Via della Ricerca Scientifica 1, 00133 Rome, Italy
| | - S. Morante
- Università di Roma “Tor Vergata” and INFN, Sezione di Roma 2 - Via della Ricerca Scientifica 1, 00133 Rome, Italy
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2
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Morante S, Botticelli S, Chiaraluce R, Consalvi V, La Penna G, Novak L, Pasquo A, Petrosino M, Proux O, Rossi G, Salina G, Stellato F. Metal Ion Binding in Wild-Type and Mutated Frataxin: A Stability Study. Front Mol Biosci 2022; 9:878017. [PMID: 35712353 PMCID: PMC9195147 DOI: 10.3389/fmolb.2022.878017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2022] [Accepted: 04/12/2022] [Indexed: 11/13/2022] Open
Abstract
This work studies the stability of wild-type frataxin and some of its variants found in cancer tissues upon Co2+ binding. Although the physiologically involved metal ion in the frataxin enzymatic activity is Fe2+, as it is customarily done, Co2+ is most often used in experiments because Fe2+ is extremely unstable owing to the fast oxidation reaction Fe2+ → Fe3+. Protein stability is monitored following the conformational changes induced by Co2+ binding as measured by circular dichroism, fluorescence spectroscopy, and melting temperature measurements. The stability ranking among the wild-type frataxin and its variants obtained in this way is confirmed by a detailed comparative analysis of the XAS spectra of the metal-protein complex at the Co K-edge. In particular, a fit to the EXAFS region of the spectrum allows positively identifying the frataxin acidic ridge as the most likely location of the metal-binding sites. Furthermore, we can explain the surprising feature emerging from a detailed analysis of the XANES region of the spectrum, showing that the longer 81-210 frataxin fragment has a smaller propensity for Co2+ binding than the shorter 90-210 one. This fact is explained by the peculiar role of the N-terminal disordered tail in modulating the protein ability to interact with the metal.
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Affiliation(s)
- S. Morante
- Dipartimento di Fisica, Universitá di Roma Tor Vergata, Rome, Italy
- INFN, Sezione di Roma Tor Vergata, Rome, Italy
- *Correspondence: S. Morante ,
| | - S. Botticelli
- Dipartimento di Fisica, Universitá di Roma Tor Vergata, Rome, Italy
- INFN, Sezione di Roma Tor Vergata, Rome, Italy
| | - R. Chiaraluce
- Dipartimento di Scienze Biochimiche “A. Rossi Fanelli”, Sapienza Universitá di Roma, Rome, Italy
| | - V. Consalvi
- Dipartimento di Scienze Biochimiche “A. Rossi Fanelli”, Sapienza Universitá di Roma, Rome, Italy
| | - G. La Penna
- INFN, Sezione di Roma Tor Vergata, Rome, Italy
- CNR—Istituto di Chimica dei Composti Organometallici, Firenze, Italy
| | - L. Novak
- Dipartimento di Scienze Biochimiche “A. Rossi Fanelli”, Sapienza Universitá di Roma, Rome, Italy
| | - A. Pasquo
- ENEA CR Frascati, Diagnostics and Metrology Laboratory FSN-TECFIS-DIM, Frascati, Italy
| | - M. Petrosino
- Chair of Pharmacology, Section of Medicine, University of Fribourg, Fribourg, Switzerland
| | - O. Proux
- Observatoire des Sciences de L’Univers de Grenoble, UAR 832 CNRS, Université Grenoble Alpes, Grenoble, France
| | - G. Rossi
- Dipartimento di Fisica, Universitá di Roma Tor Vergata, Rome, Italy
- INFN, Sezione di Roma Tor Vergata, Rome, Italy
- Museo Storico della Fisica e Centro Studi e Ricerche E. Fermi, Roma, Italy
| | - G. Salina
- INFN, Sezione di Roma Tor Vergata, Rome, Italy
| | - F. Stellato
- Dipartimento di Fisica, Universitá di Roma Tor Vergata, Rome, Italy
- INFN, Sezione di Roma Tor Vergata, Rome, Italy
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Carbonaro M, Ripanti F, Filabozzi A, Minicozzi V, Stellato F, Placidi E, Morante S, Di Venere A, Nicolai E, Postorino P, Nucara A. Human insulin fibrillogenesis in the presence of epigallocatechin gallate and melatonin: Structural insights from a biophysical approach. Int J Biol Macromol 2018; 115:1157-1164. [DOI: 10.1016/j.ijbiomac.2018.04.134] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2018] [Revised: 04/13/2018] [Accepted: 04/24/2018] [Indexed: 01/10/2023]
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Capozzi E, Aureli S, Minicozzi V, Rossi GC, Stellato F, Morante S. Designing effective anticancer-radiopeptides. A Molecular Dynamics study of their interaction with model tumor and healthy cell membranes. Biochim Biophys Acta Biomembr 2018; 1860:2348-2355. [PMID: 29883673 DOI: 10.1016/j.bbamem.2018.05.021] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/04/2018] [Revised: 05/10/2018] [Accepted: 05/31/2018] [Indexed: 11/30/2022]
Abstract
One of the greatest merit of the use of radiopeptides in oncology is their selectivity which, however, brings about the drawback that each radiopeptide is specific for a given tumor type. To overcome this problem the direction currently taken in drug design is that of radiolabelling peptide hormones (or their analogues), relying on their intrinsic ability to bind to specific receptors in precise areas of the human body, at the cost, however, of a poor selectivity against healthy cells. We present here an extensive Molecular Dynamics study of a promising alternative inspired by the mechanism through which antimicrobial peptides interact with the negatively charged bacterial membranes. Appropriately modifying the human antimicrobial peptide, LL-37, we designed a functionalized radionuclide carrier capable of binding more strongly to the negatively charged (model) tumor membranes than to the neutral healthy ones. The mechanism behind this behaviour relies on the fact that at the slight acidic pH surrounding tumor tissues the histidines belonging to the peptide get protonated thus making it positively charged. We have investigated by an extended numerical study the way in which this artificial peptide interacts with models of tumor and healthy cell membranes, proving by Potential Mean Force calculations that the affinity of the peptide to model tumor membranes is significantly larger than to healthy ones. These features (high affinity and generic tumor selectivity) recommend antimicrobial derived customized carriers as promising theranostic constructs in cancer diagnostic and therapy.
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Affiliation(s)
- E Capozzi
- University of Rome Tor Vergata and INFN, Via della Ricerca Scientifica 1, 00133 Roma, Italy
| | - S Aureli
- University of Rome Tor Vergata and INFN, Via della Ricerca Scientifica 1, 00133 Roma, Italy
| | - V Minicozzi
- University of Rome Tor Vergata and INFN, Via della Ricerca Scientifica 1, 00133 Roma, Italy.
| | - G C Rossi
- University of Rome Tor Vergata and INFN, Via della Ricerca Scientifica 1, 00133 Roma, Italy; Centro Fermi - Museo Storico della Fisica e Centro Studi e Ricerche "Enrico Fermi", Piazza del Viminale 1, Roma 00184, Italy
| | - F Stellato
- University of Rome Tor Vergata and INFN, Via della Ricerca Scientifica 1, 00133 Roma, Italy
| | - S Morante
- University of Rome Tor Vergata and INFN, Via della Ricerca Scientifica 1, 00133 Roma, Italy
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Stellato F, Fusco Z, Chiaraluce R, Consalvi V, Dinarelli S, Placidi E, Petrosino M, Rossi G, Minicozzi V, Morante S. The effect of β-sheet breaker peptides on metal associated Amyloid-β peptide aggregation process. Biophys Chem 2017; 229:110-114. [DOI: 10.1016/j.bpc.2017.05.005] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2017] [Revised: 05/09/2017] [Accepted: 05/11/2017] [Indexed: 11/30/2022]
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6
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Carbonaro M, Di Venere A, Filabozzi A, Maselli P, Minicozzi V, Morante S, Nicolai E, Nucara A, Placidi E, Stellato F. Role of dietary antioxidant (−)-epicatechin in the development of β-lactoglobulin fibrils. Biochimica et Biophysica Acta (BBA) - Proteins and Proteomics 2016; 1864:766-72. [DOI: 10.1016/j.bbapap.2016.03.017] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/24/2015] [Revised: 03/04/2016] [Accepted: 03/28/2016] [Indexed: 01/03/2023]
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7
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De Santis E, Minicozzi V, Morante S, Rossi GC, Stellato F. The role of metals in protein conformational disorders - The case of prion protein and Aβ -peptide. ACTA ACUST UNITED AC 2016. [DOI: 10.1088/1742-6596/689/1/012028] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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8
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La Penna G, Minicozzi V, Morante S, Rossi GC, Stellato F. A first-principle calculation of the XANES spectrum of Cu2+ in water. J Chem Phys 2015; 143:124508. [DOI: 10.1063/1.4931808] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Affiliation(s)
- G. La Penna
- CNR–Institute for Chemistry of Organometallic Compounds, Sesto Fiorentino 50019, Italy
| | - V. Minicozzi
- INFN, Rome “Tor Vergata,” Rome 00133, Italy
- Department of Physics, University of Rome “Tor Vergata,” Rome 00133, Italy
| | - S. Morante
- INFN, Rome “Tor Vergata,” Rome 00133, Italy
- Department of Physics, University of Rome “Tor Vergata,” Rome 00133, Italy
| | - G. C. Rossi
- INFN, Rome “Tor Vergata,” Rome 00133, Italy
- Department of Physics, University of Rome “Tor Vergata,” Rome 00133, Italy
- Centro Studi e Ricerche “Enrico Fermi,” Roma 00184, Italy
| | - F. Stellato
- INFN, Rome “Tor Vergata,” Rome 00133, Italy
- Department of Physics, University of Rome “Tor Vergata,” Rome 00133, Italy
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9
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Maiorana A, Marino T, Minicozzi V, Morante S, Russo N. A micro-environmental study of the Zn+2–Aβ1–16 structural properties. Biophys Chem 2013; 182:86-93. [DOI: 10.1016/j.bpc.2013.07.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2013] [Revised: 06/14/2013] [Accepted: 07/07/2013] [Indexed: 11/29/2022]
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11
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Brotherhood J, Petocz P, Morante S. Modelling heat stress and strain in singles tennis. J Sci Med Sport 2012. [DOI: 10.1016/j.jsams.2012.11.596] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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12
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Gañán J, Gallego-Picó A, Garcinuño RM, Fernández-Hernando P, Morante S, Sierra I, Durand JS. Development of a molecularly imprinted polymer-matrix solid-phase dispersion method for selective determination of β-estradiol as anabolic growth promoter in goat milk. Anal Bioanal Chem 2012; 403:3025-9. [DOI: 10.1007/s00216-012-5794-0] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2011] [Revised: 01/24/2012] [Accepted: 01/25/2012] [Indexed: 11/24/2022]
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13
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Cerdonio M, Congiu-Castellano A, Calabrese L, Morante S, Pispisa B, Vitale S. Room-temperature magnetic properties of oxy- and carbonmonoxyhemoglobin. Proc Natl Acad Sci U S A 2010; 75:4916-9. [PMID: 16592578 PMCID: PMC336232 DOI: 10.1073/pnas.75.10.4916] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The magnetic susceptibility and the density of human oxy-(HbO(2)) and carbonmonoxyhemoglobin (HbCO) solutions of various concentrations have been measured at room temperature, with pure water used as a calibrant. Solutions of unstripped and stripped HbO(2) at pH 7.2 in unbuffered water solvent were always found to be less diamagnetic than pure water, whereas solutions of HbCO in identical conditions were always found to be more diamagnetic than pure water. After correcting for concentration-dependent density changes and assuming the HbCO samples to be fully diamagnetic, the paramagnetic reduction of the diamagnetic susceptibility of HbO(2) corresponds to a molar susceptibility per heme (chi(M) (heme)) of 2460 +/- 600 x 10(-6) cgs/mol.
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Affiliation(s)
- M Cerdonio
- Facoltà di Scienze, Free University of Trento, POVO, Trento, Italy
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Furlan S, La Penna G, Guerrieri F, Morante S, Rossi GC. Studying the Cu binding sites in the PrP N-terminal region: a test case for ab initio simulations. Eur Biophys J 2007; 36:841-5. [PMID: 17492282 DOI: 10.1007/s00249-007-0162-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2006] [Revised: 03/09/2007] [Accepted: 03/20/2007] [Indexed: 11/25/2022]
Abstract
First principle ab initio molecular dynamics simulations of the Car-Parrinello type have proved to be of invaluable help in understanding the microscopic mechanisms of chemical bonding both in solid state physics and in structural biophysics. In this work we present as a test case a study of the Cu coordination mode at the Prion Protein binding sites localized in the N-terminal octarepeat region. Using medium size PC-clusters, we are able to deal with systems with up to about 350 atoms and 10(3) electrons for as long as approximately 2 ps. With a foreseeable forthcoming scaling up of the available CPU times by a factor 10(3), one can hope to be soon able to simulate systems of biological interest of realistic size and for physical times of the order of the nanosecond.
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Affiliation(s)
- S Furlan
- Consiglio Nazionale delle Ricerche, ISMAC, Via De Marini 6, Genoa, Italy.
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Abstract
We prove that conservation of the stress tensor is a consequence of the invariance of the partition function under canonical diffeomorphisms. From this observation a simple and general derivation of the formula which gives the local expression of the stress tensor of a molecular system in terms of its microscopic degrees of freedom readily follows. The derivation is valid in the canonical as well as the microcanonical ensemble. It works both in the classical and in the quantum mechanical settings and for arbitrary boundary conditions. In particular, if periodic boundary conditions are assigned to the system, the usual minimal-image prescription is naturally born out for mathematical consistency. An interesting outcome of our general analysis is that only in the case of a short-range interaction potential a truly local formula for the stress tensor can exist.
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Affiliation(s)
- S Morante
- Dipartimento di Fisica, INFN, Università di Roma Tor Vergata, Sezione di Roma Tor Vergata, Via della Ricerca Scientifica, 00133 Rome, Italy.
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Furlan S, La Penna G, Morante S. Modelling copper-protein backbone binding. Acta Crystallogr A 2005. [DOI: 10.1107/s0108767305086691] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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Benfatto M, Della Longa S, Qin Y, Li Q, Pan G, Wu Z, Morante S. The role of Zn in the interplay among Langmuir–Blodgett multilayer and myelin basic protein: a quantitative analysis of XANES spectra. Biophys Chem 2004; 110:191-201. [PMID: 15223154 DOI: 10.1016/j.bpc.2004.02.003] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2004] [Revised: 02/09/2004] [Accepted: 02/13/2004] [Indexed: 10/26/2022]
Abstract
We have performed a quantitative analysis of the X-ray absorption near-edge structure (XANES) spectra at the Zinc K-edge of systems formed by phospholipid Langmuir-Blodgett multilayers (LBMLs) in the presence and in the absence of myelin basic protein (MBP) and in two hydration conditions. These spectra have been analysed by a new procedure called Minuit XANes (MXAN) which is able to perform a quantitative fit of XANES data in terms of structural parameters. By this method, we have been able to correlate the relevant differences between the spectra observed in the XANES range with the coordination changes due to reduction of the space around the Zinc when the level of hydration is lowered and/or the myelin basic protein is added. These spectral differences are peculiar of the XANES energy range, and are not present in the extended X-ray absorption fine structure (EXAFS) energy range where the analysis was previously performed. With this investigation, we give an unambiguous answer to the question of the role of zinc in such complexes by showing that the metal interacts with both the phospholipid heads of the substrate and the myelin basic protein.
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Affiliation(s)
- M Benfatto
- Laboratori Nazionali di Frascati LNF-INFN, Frascati, Italy
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20
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Nuzzo S, Meneghini C, Mobilioo S, Haas H, Riccio P, Fasano A, Cavatorta P, Morante S. An x-ray absorption spectroscopy study of the zinc environment in Langmuir-Blodgett phospholipid multilayers. Biophys J 2002; 83:3507-12. [PMID: 12496117 PMCID: PMC1302425 DOI: 10.1016/s0006-3495(02)75350-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
Abstract
For the first time x-ray absorption spectroscopy was used to investigate the Zn environment in Langmuir-Blodgett multilayers. The multilayers were taken as a model of the multilamellar structure of the myelin sheath, the membrane surrounding the nerve axon, which plays a crucial role for signal transduction along the axon. The layers were assembled from the phospholipid dilauroylphosphatidic acid, both in the presence and in the absence of myelin basic protein. The analysis of the extended x-ray absorption fine structure and of the near edge regions of the x-ray absorption spectra at the Zn K-edge provided an accurate description of the local structure showing that the Zn ions are bound to the heads of the phospholipid molecules. The myelin basic protein induces a distortion on the Zn local environment due to a steric constraint but does not substitute the phosphate headgroups. These findings represent an important step in understanding the interplay among myelin basic protein, Zn, and the lipids of the myelin sheath.
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Affiliation(s)
- S Nuzzo
- Dipartimento di Fisica, University of Napoli, Naples, Italy
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21
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Menestrina G, Comai M, Potrich C, Dalla Serra M, Guella G, Frassanito R, Meneghini C, Mobilio S, Morante S. Metal ions and the conformation of peptides forming amyloid deposits in Alzheimer and prion disease. Acta Crystallogr A 2002. [DOI: 10.1107/s0108767302094801] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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Morante S. The zinc environment in Langmuir-Blodgett phospholipid multi-layers. J Synchrotron Radiat 2001; 8:975-977. [PMID: 11512999 DOI: 10.1107/s0909049500017738] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2000] [Accepted: 11/16/2000] [Indexed: 05/23/2023]
Abstract
The Zinc environment of a system formed by Langmuir-Blodgett phospholipid multi-layers is investigated by employing X-ray absorption spectroscopy. A comparative analysis of the Extended X-ray Absorption Fine Structure and Near Edge regions of the X-ray absorption spectra at the Zinc K-edge, in presence and in absence of the Myelin Basic Protein, clearly indicates that Zinc ions are bound to the heads of the phospholipidic molecules, while the presence of Myelin Basic Protein induces a visible distorsion of the geometry of the Zinc environment. These findings represent a first important step in understanding the interplay among the lipids of the myelin sheath, Myelin Basic Protein and Zinc, as Langmuir-Blodgett phospholipid multi-layers represent a valuable model for the multilamellar structure of the membrane surrounding the nerve axon.
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Affiliation(s)
- S Morante
- Dipartimento di Fiscica, Universitá di Roma Tor Vergata, Italy.
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23
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Abstract
A detailed study of the x-ray absorption spectrum of tetanus neurotoxin in the K-edge EXAFS region of the zinc absorber is presented that allows the complete identification of the amino acid residues coordinated to the zinc active site. A very satisfactory interpretation of the experimental data can be given if multiple scattering contributions are included in the analysis. Comparing the absorption spectrum of tetanus neurotoxin to that of two other structurally similar zinc-endopeptidases, thermolysin and astacin, in which the zinc coordination mode is known from crystallographic data, we conclude that in tetanus neurotoxin, besides a water molecule, zinc is coordinated to two histidines and a tyrosine.
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Affiliation(s)
- C Meneghini
- Laboratori Nazionali di Frascati INFN, 00044 Frascati, Italy
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24
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Abstract
In this paper we present a general strategy designed to study the occurrence frequency distributions of oligonucleotides in DNA coding segments and to deal with the problem of detecting possible patterns of genomic compositional inhomogeneities and disuniformities. Identifying specific tendencies or peculiar deviations in the distributions of the effective occurrence frequencies of oligonucleotides, with respect to what can be a priori expected, is of the greatest importance in biology. Differences between expected and actual distributions may in fact suggest or confirm the existence of specific biological mechanisms related to them. Similarly, a marked deviation in the occurrence frequency of an oligonucleotide may suggest that it belongs to the class of so-called "DNA signal (target) sequences". The approach we have elaborated is innovative in various aspects. Firstly, the analysis of the genomic data is carried out in the light of the observation that the distribution of the four nucleotides along the coding regions of the genoma is biased by the existence of a well-defined "reading frame". Secondly, the "experimental" numbers found by counting the occurrences of the various oligonucleotide sequences are appropriately corrected for the many kinds of mistakes and redundancies present in the available genetic Data Bases. A methodologically significant further improvement of our approach over the existing searching strategies is represented by the fact that, in order to decide whether or not the (corrected) "experimental" value of the occurrence frequency of a given oligonucleotide is within statistical expectations, a measure of the strength of the selective pressure, having acted on it in the course of the evolution, is assigned to the sequence, in a way that takes into account both the value of the "experimental" occurrence frequency of the sequence and the magnitude of the probability that this number might be the result of statistical fluctuations. If the strength of the selective pressure evaluated in this fashion turns out to be sufficiently large, the corresponding sequence will be considered to have an occurrence frequency beyond expectations and, hence, to be statistically and biologically interesting.
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Affiliation(s)
- T Castrignanò
- Dipartimento di Fisica, Università di Roma Tor Vergata Via della Ricerca Scientifica, Italy
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25
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Morante S, Furenlid L, Schiavo G, Tonello F, Zwilling R, Montecucco C. X-ray absorption spectroscopy study of zinc coordination in tetanus neurotoxin, astacin, alkaline protease and thermolysin. Eur J Biochem 1996; 235:606-12. [PMID: 8654408 DOI: 10.1111/j.1432-1033.1996.00606.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Tetanus and botulinum neurotoxins constitute a new group of Zn-endopeptidases which has been recently actively investigated with the purpose of correlating their biochemical properties to their neurobiocytosis inhibitory capacity. Crystallographic data show that Zn-endopeptidases are characterized by an active site with a Zn atom coordinated to two histidines and glutamate-bound water molecule. The two histidines and glutamate resides belong to the HEXXH motif which is characteristic of most Zn-endopeptidases. A forth metal ligand is a glutamate in thermolysin-like proteinases, but it is an histidine in the astacin family of proteinases and in alkaline protease. Astacin and alkaline protease possess a tyrosine as fifth Zn ligand, whose position in the case of alkaline protease could not be determined by X-ray crystallography. Not much is known about the atom arrangement around the active site in tetanus neurotoxin. In this work X-ray absorption spectroscopy has been used to obtain information on the Zn coordination mode in tetanus neurotoxin. The near-edge and extended fine-structure absorption spectra of this toxin are compared with those of astacin, alkaline protease and thermolysin. The present data and sequence information suggest a new pattern of Zn coordination in tetanus neurotoxin with one water molecule and three aromatic residues as metal ligands. These residues are the two histidines of the characteristic motif and a tyrosine which is tentatively identified with Tyr242, on the basis of sequence comparison and mutagenesis experiments. The mean distances of the Zn from the nearest coordinated atoms is reported. Our results indicate that alkaline protease, like astacin, also possesses a tyrosine as a fifth ligand.
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Affiliation(s)
- S Morante
- Dipartimento di Fisica, Universita' degli Studi di Roma 'Tor Vergata', Roma, Italy
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Abstract
A statistical analysis designed to deal with the problem of identifying homologous pairs of "short sequences of amino-acids" (= peptides) belonging to different proteins is presented. The conceptual novelty of the searching strategy proposed here lies in the fact that both the degree of homology of the two peptides of the pair (measured by a suitably defined affinity score) and the level of statistical significance of its occurrence are taken into account on equal footing. They are combined in a sort of "biological indicator", characterising each pair. Pairs for which the value of the biological indicator is larger than an appropriate threshold are taken as statistically significant and (putatively) biologically relevant. The method is employed in various test cases and proves to be reliable and efficient. In particular we have studied the cases in which the known existence of an auto-immune response has lead to the identification of homologous peptide pairs between human and viral or bacterial proteins. The detection efficiency of the algorithm in these cases turns out to be especially good when the most naïve affinity table, the Identity matrix, is employed to measure the similarity of amino acidic pairs. In contrast, when the 250-PAM mutation matrix is used, the detection efficiency goes to zero.
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Colosimo A, Morante S, Parisi V, Rossi GC. An improved method for detection of words with unusual occurrence frequency in nucleotide sequences. J Theor Biol 1993; 165:659-72. [PMID: 8114510 DOI: 10.1006/jtbi.1993.1212] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
A statistical analysis designed to deal with the problem of identifying rare or abundant "words" of arbitrary length in genomic fragments is presented. Our approach has the novelty of taking into account the statistical role of the presence of shorter words nested into longer ones and of introducing a Bayesian correction to minimize the effects of statistical fluctuations and of possible mistakes in genomic data. The method is successfully used in a thorough analysis of the abundance of short nucleotide sequences in the Escherichia coli genome.
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Affiliation(s)
- A Colosimo
- Dipartimento di Scienze Biochimiche, Università degli Studi di Roma, La Sapienza, Italia
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Strange R, Morante S, Stefanini S, Chiancone E, Desideri A. Nucleation of the iron core occurs at the three-fold channels of horse spleen apoferritin: an EXAFS study on the native and chemically-modified protein. Biochim Biophys Acta 1993; 1164:331-4. [PMID: 8343534 DOI: 10.1016/0167-4838(93)90267-u] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Extended X-ray absorbance fine structure measurements have been carried out on the initial Fe(III)-apoferritin complex at a Fe/subunit ratio of 2 in native and modified horse spleen apoferritin. Analysis of the data indicates that in the native protein the iron forms a protein-bound polynuclear cluster (Fe-Fe distance 3.4 A) with a first coordination sphere constituted by 5-6 low-Z atoms, e.g., nitrogen atoms, carboxylate-like ligands or oxo bridges between the iron atoms. Modification of Cys-126, a residue localized on the outer surface of the hydrophilic three-fold channels, with p-chloromercuribenzoate (PMB) or phenylmercuric acetate (PMA) brings about distinctive differences. In particular, in the PMB-reacted protein the feature assigned to the iron-iron interaction disappears from the spectrum, whilst in the PMA-reacted protein the main differences with respect to the native protein are observed at the level of the first coordination sphere. These results confirm the formation of protein-Fe(III)-clusters and localize these sites at the hydrophilic three-fold channels of horse spleen apoferritin.
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Affiliation(s)
- R Strange
- Daresbury Laboratory, Warrington, UK
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30
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Balzarotti V, Colizzi V, Morante S, Parisi V. An algorithm for the identification of similar oligopeptides between amino acid sequences. Comput Appl Biosci 1993; 9:93-100. [PMID: 8435775 DOI: 10.1093/bioinformatics/9.1.93] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Molecular mimicry is the origin of common structural patterns in sequences of viral and host proteins, and it appears to be related to the development of autoimmune diseases. The identification of structural molecular similarities among viral and host proteins is thus very relevant in the development of engineered antiviral vaccines to avoid potentially dangerous effects. In this respect identifying pairs of similar oligopeptides between given proteins, independently of the overall degree of similarity of their amino acid sequences, is of interest. To this aim we have designed and implemented an algorithm capable of finding and classifying (with respect to their statistical significance) all possible pairs of similar oligopeptides between two proteins irrespective of length, number, location and ordering of the pairs along the sequences. The algorithm is very efficient and much more suited for this kind of local search than standard alignment programs. The latter, dealing with the sequences as a whole, are, in these cases, of very limited applicability. We have used the algorithm to compare a glycoprotein of the human immunodeficiency virus (HIV) type 1 and with the beta-chains of human leukocyte antigen (HLA). Besides a previously identified peptide, we have found a new peptide located in the fusion site of HIV that shares high similarity with the transmembrane domains of HLA.
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Affiliation(s)
- V Balzarotti
- Department of Physics, University of Rome Tor Vergata, Italy
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Cordiali P, Balzarotti V, Morante S, Parisi V, Pugliese O, Camponeschi B, Colizzi V. Convergent evolution in the homology between HIV gp160 and HLA class II molecules. AIDS Res Hum Retroviruses 1992; 8:1561-5. [PMID: 1457201 DOI: 10.1089/aid.1992.8.1561] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
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Menestrina G, Belmonte G, Parisi V, Morante S. Structural features of the pore formed by Staphylococcus aureus alpha-toxin inferred from chemical modification and primary structure analysis. FEMS Microbiol Immunol 1992; 5:19-28. [PMID: 1384596 DOI: 10.1111/j.1574-6968.1992.tb05882.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Staphylococcus aureus alpha-toxin makes cells and model membranes permeable to ions and uncharged molecules by opening oligomeric pores of uniform size. Its primary sequence reveals peculiar features which give some hints on the structure of the pore. A flexible region separating the toxin into two halves, several amphiphilic beta-strands and two amphiphilic alpha-helices long enough to span the hydrophobic core of the lipid bilayer are predicted. In analogy to bacterial porins, we propose that the inner walls of the pore are, at least in part, built by an amphiphilic beta-barrel. The model is consistent with circular dichroism data and with the electrophysiological properties of the pore. Functional information on this toxin were obtained by chemical modification of its four histidine residues. Specific carbethoxylation suggested they have different roles: one is required for specific receptor binding, one for oligomerisation and two for unspecific lipid binding. A tentative assignment of each histidine to its specific role is done on the basis of the structural predictions. A functionally related hemolysin, Aeromonas hydrophyla aerolysin, reveals remarkably similar features including the presence and location of histidines involved in receptor binding and oligomerisation.
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Affiliation(s)
- G Menestrina
- Dipartimento di Fisica, Università di Trento, Italy
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Morante S, Parisi V. Building structural models of peptides: a semi-automatic software. Comput Appl Biosci 1991; 7:21-6. [PMID: 2004270 DOI: 10.1093/bioinformatics/7.1.21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
We present a software package that allows the construction and display of structural models of proteins starting from the amino acid sequence written in the one-letter code of standard data bank format. The software includes a very fast and efficient algorithm aimed at finding the global energy minimum of the potential function describing the molecular interactions. The whole package is conceived to have maximum flexibility. Completely automatic procedures are envisaged for standard problems. For non-standard problems, the construction procedure can be interactively adopted to meet with different options.
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Affiliation(s)
- S Morante
- Dipartimento di Fisica, Universita degli Studi di Roma Tor Vergata, Italy
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Abstract
X-ray absorption spectroscopy has been applied to the in vivo examination of copper-resistant yeast cells. The in vivo structure of the metal-binding site of the accumulated copper has been compared to that of the purified yeast thionein. Analysis of the EXAFS spectra performed on intact yeast cells indicates that the accumulated copper is univalent and is exclusively coordinated to sulfur atoms at a distance of 219 pm with an average coordination number of 2. In contrast, the purified protein indicates a univalent copper trigonally coordinated to sulfur at a distance of 221 pm. These discrepancies are discussed in terms of copper location in the resistant yeast cells.
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Affiliation(s)
- A Desideri
- Department of Biology, University of Rome Tor vergata, Italy
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Desideri A, Falconi M, Parisi V, Morante S, Rotilio G. Is the activity-linked electrostatic gradient of bovine Cu, Zn superoxide dismutases conserved in homologous enzymes irrespective of the number and distribution of charges? Free Radic Biol Med 1988; 5:313-7. [PMID: 3256530 DOI: 10.1016/0891-5849(88)90102-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Electrostatic potential calculations have been performed on three different Cu, Zn superoxide dismutases (superoxide: superoxide oxidoreductase, EC 1.15. 1.1), in order to evaluate the degree of conservation of the pattern of electrostatic interactions between O2- and the active site recently pointed out in bovine Cu Zn SOD. The three Cu, Zn SODs that have been selected for this study, namely the bovine, ovine, and porcine enzymes, are highly homologous as to reasonably assume identical three-dimensional structure but display large differences in their net charge, as shown by their pI's, which span over a wide pH range: 8.0 (sheep), 6.5 (pig), 5.2 (ox). Despite such a large difference in the net protein charge and in the spatial arrangement of electrostatic charges, electrostatic potential calculations show that the electrostatic channel directing the negatively charged substrate toward the positive catalytic site is strictly preserved with the same features for the three proteins. This suggests that the electrostatic funnel for conducting small anions into the active site is a highly conservative property in the evolution of Cu, Zn SOD.
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Affiliation(s)
- A Desideri
- Department of Biology Tor Vergata University, Rome, Italy
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Noble RW, De Young A, Vitale S, Morante S, Cerdonio M. Studies on the linkage between spin equilibria and protein structure in carp ferric hemoglobin. Eur J Biochem 1987; 168:563-7. [PMID: 2822419 DOI: 10.1111/j.1432-1033.1987.tb13454.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The effects of protein conformation on the spin-state equilibria of several derivatives of carp hemoglobin have been examined. This has been done by measuring the pH dependence of the paramagnetic susceptibilities of these derivatives in the presence and absence of inositol hexakisphosphate, P6-inositol. In all cases the addition of P6-inositol at low pH and the lowering of the pH in the presence of P6-inositol shift the spin-state equilibrium in favor of the high-spin electronic configuration. The P6-inositol and pH dependence of these magnetic properties parallels the pH and P6-inositol dependence of the conformational state of the hemoglobin as determined in earlier studies and further supports a thermodynamic linkage between the electronic state of the iron atoms and the quaternary structure of the hemoglobin molecule.
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Affiliation(s)
- R W Noble
- Veteran's Administration Medical Center, New York City, New York
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Bianconi A, Congiu-Castellano A, Dell'Ariccia M, Giovannelli A, Morante S, Burattini E, Durham PJ. Local Fe site structure in the tense-to-relaxed transition in carp deoxyhemoglobin: a XANES (x-ray absorption near edge structure) study. Proc Natl Acad Sci U S A 1986; 83:7736-40. [PMID: 3463997 PMCID: PMC386796 DOI: 10.1073/pnas.83.20.7736] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
The Fe-site structure variation in the transition from the low-affinity tense (T) quaternary structure to the high-affinity relaxed (R) structure in carp deoxyhemoglobin was studied by analysis of multiple scattering resonances in the XANES (x-ray absorption near edge structure) spectra. High signal-to-noise XANES spectra were measured at the Frascati "wiggler" synchrotron radiation facility. We find that the forces on the Fe active site due to the change of quaternary protein conformation do not induce variations greater than 0.01 A in interatomic Fe-N distances, variations greater than 0.1 A in the Fe displacement toward the heme plane, or the "doming" of the heme. The relevance of these results to the mechanism of protein control of ligand binding is discussed.
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Bianconi A, Congiu-Castellano A, Dell'Ariccia M, Giovannelli A, Burattini E, Durham P, Giacometti G, Morante S. Determination of CO and CN bond angles by X-ray absorption near edge structure in chelated protoheme in solution. ACTA ACUST UNITED AC 1985. [DOI: 10.1016/0167-4838(85)90157-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Durham P, Bianconi A, Congiu-Castellano A, Giovannelli A, Hasnain SS, Incoccia L, Morante S, Pendry JB. X-ray absorption near edge structure (XANES) for CO, CN and deoxyhaemoglobin: geometrical information. EMBO J 1983; 2:1441-3. [PMID: 11892793 PMCID: PMC555298 DOI: 10.1002/j.1460-2075.1983.tb01605.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
We use the recently developed multiple scattering theory to give a quantitative analysis of the X-ray absorption near edge structure (XANES) of haemoglobin and some of its substituents. We demonstrate that the XANES may contain information not provided by the extended X-ray absorption fine structure (EXAFS) part of the spectrum about the coordination geometry around the Fe atom, and in particular discuss the sensitivity of the XANES to the orientation of the CN group in HbCN. The anisotropy of the system leads to a strong dependence of the calculated spectrum on the polarisation of the X-rays. We show how this effect can be exploited in further XANES structural studies.
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Affiliation(s)
- P Durham
- Daresbury Laboratory, Warrington, UK
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Noble RW, De Young A, Di Iorio E, Winterhalter KH, Cerdonio M, Morante S, Vitale S. Quaternary structure and spin equilibria in ferric hemoglobins. A room temperature study. Eur J Biochem 1983; 133:475-8. [PMID: 6852055 DOI: 10.1111/j.1432-1033.1983.tb07488.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
The effective magnetic moments for a number of human and carp methemoglobin derivatives were determined in solution at room temperature. The data permit us to confirm the dependence of the spin-state equilibrium of azide methemoglobin on the quarternary state of the hemoglobin and to demonstrate a similar dependence for both human and carp aquomethemoglobin. In addition, the pH dependence of the effective magnetic moment and the Soret spectrum of carp azidemethemoglobin are compared.
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Cerdonio M, Morante S, Vitale S, Dalvit C, Russu IM, Ho C, de Young A, Noble RW. Magnetic and spectral properties of carp carbonmonoxyhemoglobin. Competitive effects of chloride ions and inositol hexakisphosphate. Eur J Biochem 1983; 132:461-7. [PMID: 6852007 DOI: 10.1111/j.1432-1033.1983.tb07384.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
We have extended our studies on the magnetic properties of carp carbonmonoxyhemoglobin and the dependence of these properties upon solution variables. Using an improved version of the superconducting magnetometer, we have found that the magnetic susceptibility of carp carbonmonoxyhemoglobin is sensitive to both inositol hexakisphosphate and chloride ion. The dependence upon chloride ion concentration is complex. At relatively low concentrations this anion reverses the effect of inositol hexakisphosphate, restoring paramagnetism. At higher chloride concentrations the protein is converted to a roughly diamagnetic state in the absence of inositol hexakisphosphate. Along with these susceptibility studies, we have examined the effects of these anions on other properties of carp carbonmonoxyhemoglobin. The positions of the Soret bands of human and carp methemoglobin derivatives are correlated with spin state; changes in the magnetic susceptibility of carbonmonoxyhemoglobin are similarly associated with alterations in this spectral band. We have also examined the effects of these anions on the proton nuclear magnetic resonance spectrum of carp carbonmonoxyhemoglobin. Both chloride and inositol hexakisphosphate alter the position of the proton resonances in the ring-current-shifted region of the spectrum.
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Cerdonio M, Morante S, Vitale S, Di Iorio E, Winterhalter K, Giacometti G, Brunori M. Magnetic equivalence of the hemes in hemoglobin Zürich. J Biol Chem 1980. [DOI: 10.1016/s0021-9258(18)43716-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
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Cerdonio M, Morante S, Vitale S, Di Iorio EE, Winterhalter KH, Giacometti GM, Brunori M. Magnetic equivalence of the hemes in hemoglobin Zürich. J Biol Chem 1980; 255:6166-7. [PMID: 7391014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
The magnetic susceptibilities of solutions of deoxyhemoglobin Zürich and deoxyhemoglobin A have been found quite close together, in contrast to previous findings. Therefore, any magnetic inequivalence between alpha- and beta-hemes must be confined to finer details.
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Cerdonio M, Morante S, Vitale S, De Young A, Noble RW. Variability of the magnetic moment of carbon monoxide hemoglobin from carp. Proc Natl Acad Sci U S A 1980; 77:1462-5. [PMID: 6929497 PMCID: PMC348515 DOI: 10.1073/pnas.77.3.1462] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Deionized carp carbon monoxide hemoglobin in distilled water or in bis(2-hydroxyethyl)imino-tris(hydroxymethyl)methane or Tris buffer exhibits a slight but significant paramagnetism. This is most clearly demonstrated by the decrease in this paramagnetism that is caused by the addition of inositol hexaphosphate to this protein in the former buffer at pH 6.3-6.4. No such effect is seen when inositol hexaphosphate is added to carp cyanomethemoglobin, demonstrating that the change observed with carbon monoxide derivative is not due to a modification in the diamagnetic properties of the protein.
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