1
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Structural details on the interaction of fenamates with lipid membranes. J Mol Liq 2022. [DOI: 10.1016/j.molliq.2022.120502] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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2
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Leppkes J, Dimos N, Loll B, Hohmann T, Dyrks M, Wieseke A, Keller BG, Koksch B. Fluorine-induced polarity increases inhibitory activity of BPTI towards chymotrypsin. RSC Chem Biol 2022; 3:773-782. [PMID: 35755190 PMCID: PMC9175108 DOI: 10.1039/d2cb00018k] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2022] [Accepted: 05/06/2022] [Indexed: 11/21/2022] Open
Abstract
Substituting the P1 position in bovine pancreatic trypsin inhibitor (BPTI) is known to heavily influence its inhibitory activity towards serine proteases. Side-chain fluorinated aliphatic amino acids have been shown to alter numerous properties of peptides and proteins and thus are of interest in the context of BPTI. In our study, we systematically investigated the site-specific incorporation of non-canonical amino acids into BPTI by microwave-assisted solid-phase peptide synthesis (SPPS). Inhibitor activity of the variants was tested towards the serine protease α-chymotrypsin. We observed enhanced inhibition of two fluorinated BPTIs compared to wild type and hydrocarbon variants. To further investigate the complexes, we performed X-ray structure analysis. Our findings underline the power fluorine offers as a tool in protein engineering to beneficially alter the effects on phenomena as protein-protein interactions.
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Affiliation(s)
- Jakob Leppkes
- Department of Biology, Chemistry and Pharmacy, Institute of Chemistry and Biochemistry, Freie Universität Berlin Arnimallee 20 14195 Berlin Germany
| | - Nicole Dimos
- Department of Biology, Chemistry and Pharmacy, Institute of Chemistry and Biochemistry, Structural Biochemistry, Freie Universität Berlin Takustr. 6 14195 Berlin Germany
| | - Bernhard Loll
- Department of Biology, Chemistry and Pharmacy, Institute of Chemistry and Biochemistry, Structural Biochemistry, Freie Universität Berlin Takustr. 6 14195 Berlin Germany
| | - Thomas Hohmann
- Department of Biology, Chemistry and Pharmacy, Institute of Chemistry and Biochemistry, Freie Universität Berlin Arnimallee 20 14195 Berlin Germany
| | - Michael Dyrks
- Department of Biology, Chemistry and Pharmacy, Institute of Chemistry and Biochemistry, Freie Universität Berlin Arnimallee 20 14195 Berlin Germany
| | - Ariane Wieseke
- Department of Biology, Chemistry and Pharmacy, Institute of Chemistry and Biochemistry, Freie Universität Berlin Arnimallee 20 14195 Berlin Germany
| | - Bettina G Keller
- Department of Biology, Chemistry and Pharmacy, Institute of Chemistry and Biochemistry, Freie Universität Berlin Arnimallee 22 14195 Berlin Germany
| | - Beate Koksch
- Department of Biology, Chemistry and Pharmacy, Institute of Chemistry and Biochemistry, Freie Universität Berlin Arnimallee 20 14195 Berlin Germany
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3
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Wüthrich K. Brownian motion, spin diffusion and protein structure determination in solution. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2021; 331:107031. [PMID: 34391647 DOI: 10.1016/j.jmr.2021.107031] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2021] [Revised: 06/28/2021] [Accepted: 06/29/2021] [Indexed: 06/13/2023]
Abstract
This paper presents my recollections on the development of protein structure determination by NMR in solution from 1968 to 1992. The key to success was to identify NMR-accessible parameters that unambiguously determine the spatial arrangement of polypeptide chains. Inspired by work with cyclopeptides, model considerations showed that enforcing short non-bonding interatomic distances imposes «ring closure conditions» on polypeptide chains. Given that distances are scalar parameters, this indicated an avenue for studies of proteins in solution, i.e., under the regime of stochastic rotational and translational motions at frequencies in the nanosecond range (Brownian motion), where sharp pictures could not be obtained by photography-related methods. Later-on, we used distance geometry calculations with sets of inter-atomic distances derived from protein crystal structures to confirm that measurements of short proton-proton distances could provide atomic-resolution structures of globular proteins. During the years 1976-1984 the following four lines of research then led to protein structure determination by NMR in solution. First, the development of NMR experiments enabling the use of the nuclear Overhauser effect (NOE) for measurements of interatomic distances between pairs of hydrogen atoms in proteins. Second, obtaining sequence-specific resonance assignment solved the "phase problem" for protein structure determination by NMR. Third, generating and programming novel distance geometry algorithms enabled the calculation of atomic-resolution protein structures from limited sets of distance constraints measured by NMR. Fourth, the introduction of two-dimensional NMR provided greatly improved spectral resolution of the complex spectra of proteins as well as efficient delineation of scalar and dipole-dipole 1H-1H connectivities, thus making protein structure determination in solution viable and attractive.
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Affiliation(s)
- Kurt Wüthrich
- ETH Zürich, Zürich Switzerland and Scripps Research, La Jolla, CA, USA
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4
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Cucuzza S, Güntert P, Plückthun A, Zerbe O. An automated iterative approach for protein structure refinement using pseudocontact shifts. JOURNAL OF BIOMOLECULAR NMR 2021; 75:319-334. [PMID: 34338940 PMCID: PMC8473369 DOI: 10.1007/s10858-021-00376-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Accepted: 07/19/2021] [Indexed: 05/02/2023]
Abstract
NMR structure calculation using NOE-derived distance restraints requires a considerable number of assignments of both backbone and sidechains resonances, often difficult or impossible to get for large or complex proteins. Pseudocontact shifts (PCSs) also play a well-established role in NMR protein structure calculation, usually to augment existing structural, mostly NOE-derived, information. Existing refinement protocols using PCSs usually either require a sizeable number of sidechain assignments or are complemented by other experimental restraints. Here, we present an automated iterative procedure to perform backbone protein structure refinements requiring only a limited amount of backbone amide PCSs. Already known structural features from a starting homology model, in this case modules of repeat proteins, are framed into a scaffold that is subsequently refined by experimental PCSs. The method produces reliable indicators that can be monitored to judge about the performance. We applied it to a system in which sidechain assignments are hardly possible, designed Armadillo repeat proteins (dArmRPs), and we calculated the solution NMR structure of YM4A, a dArmRP containing four sequence-identical internal modules, obtaining high convergence to a single structure. We suggest that this approach is particularly useful when approximate folds are known from other techniques, such as X-ray crystallography, while avoiding inherent artefacts due to, for instance, crystal packing.
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Affiliation(s)
- Stefano Cucuzza
- Department of Chemistry, University of Zürich, Winterthurerstrasse 190, 8057, Zürich, Switzerland
| | - Peter Güntert
- Institute of Biophysical Chemistry and Center for Biomolecular Magnetic Resonance, Goethe University Frankfurt, Max-von-Laue-Straße 9, 60438, Frankfurt am Main, Germany
- Laboratory of Physical Chemistry, ETH Zürich, Vladimir-Prelog-Weg 2, 8093, Zürich, Switzerland
- Department of Chemistry, Tokyo Metropolitan University, 1-1 Minami-Osawa, Hachioji, 192-0397, Tokyo, Japan
| | - Andreas Plückthun
- Department of Biochemistry, University of Zürich, Winterthurerstrasse 190, 8057, Zürich, Switzerland
| | - Oliver Zerbe
- Department of Chemistry, University of Zürich, Winterthurerstrasse 190, 8057, Zürich, Switzerland.
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5
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Kupče Ē, Mote KR, Webb A, Madhu PK, Claridge TDW. Multiplexing experiments in NMR and multi-nuclear MRI. PROGRESS IN NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY 2021; 124-125:1-56. [PMID: 34479710 DOI: 10.1016/j.pnmrs.2021.03.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2020] [Revised: 02/28/2021] [Accepted: 03/02/2021] [Indexed: 05/22/2023]
Abstract
Multiplexing NMR experiments by direct detection of multiple free induction decays (FIDs) in a single experiment offers a dramatic increase in the spectral information content and often yields significant improvement in sensitivity per unit time. Experiments with multi-FID detection have been designed with both homonuclear and multinuclear acquisition, and the advent of multiple receivers on commercial spectrometers opens up new possibilities for recording spectra from different nuclear species in parallel. Here we provide an extensive overview of such techniques, designed for applications in liquid- and solid-state NMR as well as in hyperpolarized samples. A brief overview of multinuclear MRI is also provided, to stimulate cross fertilization of ideas between the two areas of research (NMR and MRI). It is shown how such techniques enable the design of experiments that allow structure elucidation of small molecules from a single measurement. Likewise, in biomolecular NMR experiments multi-FID detection allows complete resonance assignment in proteins. Probes with multiple RF microcoils routed to multiple NMR receivers provide an alternative way of increasing the throughput of modern NMR systems, effectively reducing the cost of NMR analysis and increasing the information content at the same time. Solid-state NMR experiments have also benefited immensely from both parallel and sequential multi-FID detection in a variety of multi-dimensional pulse schemes. We are confident that multi-FID detection will become an essential component of future NMR methodologies, effectively increasing the sensitivity and information content of NMR measurements.
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Affiliation(s)
- Ēriks Kupče
- Bruker UK Ltd., Banner Lane, Coventry CV4 9GH, United Kingdom.
| | - Kaustubh R Mote
- TIFR Centre for Interdisciplinary Sciences, Tata Institute of Fundamental Research-Hyderabad, 36/P Gopanpally Village, Ranga Reddy District, Hyderabad 500 046, Telangana, India
| | - Andrew Webb
- Department of Radiology, Leiden University Medical Center, Albinusdreef 2, 2333 ZA Leiden, Netherlands
| | - Perunthiruthy K Madhu
- TIFR Centre for Interdisciplinary Sciences, Tata Institute of Fundamental Research-Hyderabad, 36/P Gopanpally Village, Ranga Reddy District, Hyderabad 500 046, Telangana, India
| | - Tim D W Claridge
- Department of Chemistry, University of Oxford, Chemistry Research Laboratory, Mansfield Road, Oxford OX1 3TA, UK
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6
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Armstrong DA, Jin AH, Braga Emidio N, Lewis RJ, Alewood PF, Rosengren KJ. Chemical Synthesis and NMR Solution Structure of Conotoxin GXIA from Conus geographus. Mar Drugs 2021; 19:md19020060. [PMID: 33530397 PMCID: PMC7912261 DOI: 10.3390/md19020060] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Revised: 01/07/2021] [Accepted: 01/19/2021] [Indexed: 12/30/2022] Open
Abstract
Conotoxins are disulfide-rich peptides found in the venom of cone snails. Due to their exquisite potency and high selectivity for a wide range of voltage and ligand gated ion channels they are attractive drug leads in neuropharmacology. Recently, cone snails were found to have the capability to rapidly switch between venom types with different proteome profiles in response to predatory or defensive stimuli. A novel conotoxin, GXIA (original name G117), belonging to the I3-subfamily was identified as the major component of the predatory venom of piscivorous Conus geographus. Using 2D solution NMR spectroscopy techniques, we resolved the 3D structure for GXIA, the first structure reported for the I3-subfamily and framework XI family. The 32 amino acid peptide is comprised of eight cysteine residues with the resultant disulfide connectivity forming an ICK+1 motif. With a triple stranded β-sheet, the GXIA backbone shows striking similarity to several tarantula toxins targeting the voltage sensor of voltage gated potassium and sodium channels. Supported by an amphipathic surface, the structural evidence suggests that GXIA is able to embed in the membrane and bind to the voltage sensor domain of a putative ion channel target.
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Affiliation(s)
- David A. Armstrong
- School of Biomedical Sciences, Faculty of Medicine, The University of Queensland, Brisbane, QLD 4072, Australia;
| | - Ai-Hua Jin
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4072, Australia; (A.-H.J.); (N.B.E.); (R.J.L.); (P.F.A.)
| | - Nayara Braga Emidio
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4072, Australia; (A.-H.J.); (N.B.E.); (R.J.L.); (P.F.A.)
| | - Richard J. Lewis
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4072, Australia; (A.-H.J.); (N.B.E.); (R.J.L.); (P.F.A.)
| | - Paul F. Alewood
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4072, Australia; (A.-H.J.); (N.B.E.); (R.J.L.); (P.F.A.)
| | - K. Johan Rosengren
- School of Biomedical Sciences, Faculty of Medicine, The University of Queensland, Brisbane, QLD 4072, Australia;
- Correspondence:
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7
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Müntener T, Böhm R, Atz K, Häussinger D, Hiller S. NMR pseudocontact shifts in a symmetric protein homotrimer. JOURNAL OF BIOMOLECULAR NMR 2020; 74:413-419. [PMID: 32621004 PMCID: PMC7508745 DOI: 10.1007/s10858-020-00329-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Accepted: 06/25/2020] [Indexed: 06/11/2023]
Abstract
NMR pseudocontact shifts are a valuable tool for structural and functional studies of proteins. Protein multimers mediate key functional roles in biology, but methods for their study by pseudocontact shifts are so far not available. Paramagnetic tags attached to identical subunits in multimeric proteins cause a combined pseudocontact shift that cannot be described by the standard single-point model. Here, we report pseudocontact shifts generated simultaneously by three paramagnetic Tm-M7PyThiazole-DOTA tags to the trimeric molecular chaperone Skp and provide an approach for the analysis of this and related symmetric systems. The pseudocontact shifts were described by a "three-point" model, in which positions and parameters of the three paramagnetic tags were fitted. A good correlation between experimental data and predicted values was found, validating the approach. The study establishes that pseudocontact shifts can readily be applied to multimeric proteins, offering new perspectives for studies of large protein complexes by paramagnetic NMR spectroscopy.
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Affiliation(s)
- Thomas Müntener
- Biozentrum, University of Basel, Klingelbergstrasse 70, 4056, Basel, Switzerland
| | - Raphael Böhm
- Biozentrum, University of Basel, Klingelbergstrasse 70, 4056, Basel, Switzerland
| | - Kenneth Atz
- Biozentrum, University of Basel, Klingelbergstrasse 70, 4056, Basel, Switzerland
| | - Daniel Häussinger
- Department of Chemistry, University of Basel, St. Johanns-Ring 19, 4056, Basel, Switzerland
| | - Sebastian Hiller
- Biozentrum, University of Basel, Klingelbergstrasse 70, 4056, Basel, Switzerland.
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8
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Nikitina LE, Pavelyev RS, Startseva VA, Kiselev SV, Galiullina LF, Aganova OV, Timerova AF, Boichuk SV, Azizova ZR, Klochkov VV, Huster D, Khodov IA, Scheidt HA. Structural details on the interaction of biologically active sulfur-containing monoterpenoids with lipid membranes. J Mol Liq 2020. [DOI: 10.1016/j.molliq.2019.112366] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
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9
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Kupče Ē, Mote KR, Madhu PK. Experiments with direct detection of multiple FIDs. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2019; 304:16-34. [PMID: 31077929 DOI: 10.1016/j.jmr.2019.04.018] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/03/2019] [Revised: 03/26/2019] [Accepted: 04/29/2019] [Indexed: 05/04/2023]
Abstract
Pulse schemes with direct observation of multiple free induction decays (FIDs) offer a dramatic increase in the spectral information content of NMR experiments and often yield substantial improvement in measurement sensitivity per unit time. Availability of multiple receivers on the state-of-the-art commercial spectrometers allows spectra from different nuclear species to be recorded in parallel routinely. Experiments with multi-FID detection have been designed with both, homonuclear and multinuclear acquisition. We provide a brief overview of such techniques designed for applications in liquid- and solid- state NMR as well as in hyperpolarized samples. Here we show how these techniques have led to design of experiments that allow structure elucidation of small molecules and resonance assignment in proteins from a single measurement. Probes with multiple RF micro-coils routed to multiple NMR receivers provide an alternative way of increasing the throughput of modern NMR systems. Solid-state NMR experiments have also benefited immensely from both parallel and simultaneous FID acquisition in a variety of multi-dimensional pulse schemes. We believe that multi-FID detection will become an essential component of the future NMR methodologies effectively increasing the information content of NMR experiments and reducing the cost of NMR analysis.
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Affiliation(s)
- Ēriks Kupče
- Bruker UK Ltd., Banner Lane, Coventry CV4 9GH, United Kingdom.
| | - Kaustubh R Mote
- TIFR Centre for Interdisciplinary Sciences, Tata Institute of Fundamental Research Hyderabad, 36/P Gopanpally Village, Ranga Reddy District, Hyderabad 500107, India
| | - Perunthiruthy K Madhu
- TIFR Centre for Interdisciplinary Sciences, Tata Institute of Fundamental Research Hyderabad, 36/P Gopanpally Village, Ranga Reddy District, Hyderabad 500107, India
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10
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van Emmerik CL, van Ingen H. Unspinning chromatin: Revealing the dynamic nucleosome landscape by NMR. PROGRESS IN NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY 2019; 110:1-19. [PMID: 30803691 DOI: 10.1016/j.pnmrs.2019.01.002] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2018] [Revised: 01/15/2019] [Accepted: 01/15/2019] [Indexed: 05/09/2023]
Abstract
NMR is an essential technique for obtaining information at atomic resolution on the structure, motions and interactions of biomolecules. Here, we review the contribution of NMR to our understanding of the fundamental unit of chromatin: the nucleosome. Nucleosomes compact the genome by wrapping the DNA around a protein core, the histone octamer, thereby protecting genomic integrity. Crucially, the imposed barrier also allows strict regulation of gene expression, DNA replication and DNA repair processes through an intricate system of histone and DNA modifications and a wide range of interactions between nucleosomes and chromatin factors. In this review, we describe how NMR has contributed to deciphering the molecular basis of nucleosome function. Starting from pioneering studies in the 1960s using natural abundance NMR studies, we focus on the progress in sample preparation and NMR methodology that has allowed high-resolution studies on the nucleosome and its subunits. We summarize the results and approaches of state-of-the-art NMR studies on nucleosomal DNA, histone complexes, nucleosomes and nucleosomal arrays. These studies highlight the particular strength of NMR in studying nucleosome dynamics and nucleosome-protein interactions. Finally, we look ahead to exciting new possibilities that will be afforded by on-going developments in solution and solid-state NMR. By increasing both the depth and breadth of nucleosome NMR studies, it will be possible to offer a unique perspective on the dynamic landscape of nucleosomes and its interacting proteins.
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Affiliation(s)
- Clara L van Emmerik
- Bijvoet Center for Biomolecular Research, Utrecht University, Utrecht, the Netherlands.
| | - Hugo van Ingen
- Bijvoet Center for Biomolecular Research, Utrecht University, Utrecht, the Netherlands.
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11
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Schmidt EY, Bidusenko IA, Cherimichkina NA, Ushakov IA, Trofimov BA. Polycyclic bridgehead acetals with enol functionality: one-pot assembly from aliphatic ketones and acetylene in KOH/DMSO suspension. Tetrahedron 2016. [DOI: 10.1016/j.tet.2016.06.010] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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12
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Jadeja Y, Kapadiya K, Shah A, Khunt R. Importance of HMBC and NOE 2D NMR techniques for the confirmation of regioselectivity. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2016; 54:75-80. [PMID: 26307589 DOI: 10.1002/mrc.4315] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/25/2015] [Revised: 07/11/2015] [Accepted: 07/18/2015] [Indexed: 06/04/2023]
Affiliation(s)
- Yashwantsinh Jadeja
- National Facility for Drug Discovery Centre, Department of Chemistry, Saurashtra University, Rajkot, Gujarat, 360005, India
| | - Khushal Kapadiya
- National Facility for Drug Discovery Centre, Department of Chemistry, Saurashtra University, Rajkot, Gujarat, 360005, India
| | - Anamik Shah
- National Facility for Drug Discovery Centre, Department of Chemistry, Saurashtra University, Rajkot, Gujarat, 360005, India
| | - Ranjan Khunt
- National Facility for Drug Discovery Centre, Department of Chemistry, Saurashtra University, Rajkot, Gujarat, 360005, India
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13
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Ward ME, Ritz E, Ahmed MAM, Bamm VV, Harauz G, Brown LS, Ladizhansky V. Proton detection for signal enhancement in solid-state NMR experiments on mobile species in membrane proteins. JOURNAL OF BIOMOLECULAR NMR 2015; 63:375-388. [PMID: 26494649 DOI: 10.1007/s10858-015-9997-5] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/02/2015] [Accepted: 10/15/2015] [Indexed: 05/09/2023]
Abstract
Direct proton detection is becoming an increasingly popular method for enhancing sensitivity in solid-state nuclear magnetic resonance spectroscopy. Generally, these experiments require extensive deuteration of the protein, fast magic angle spinning (MAS), or a combination of both. Here, we implement direct proton detection to selectively observe the mobile entities in fully-protonated membrane proteins at moderate MAS frequencies. We demonstrate this method on two proteins that exhibit different motional regimes. Myelin basic protein is an intrinsically-disordered, peripherally membrane-associated protein that is highly flexible, whereas Anabaena sensory rhodopsin is composed of seven rigid transmembrane α-helices connected by mobile loop regions. In both cases, we observe narrow proton linewidths and, on average, a 10× increase in sensitivity in 2D insensitive nuclear enhancement of polarization transfer-based HSQC experiments when proton detection is compared to carbon detection. We further show that our proton-detected experiments can be easily extended to three dimensions and used to build complete amino acid systems, including sidechain protons, and obtain inter-residue correlations. Additionally, we detect signals which do not correspond to amino acids, but rather to lipids and/or carbohydrates which interact strongly with membrane proteins.
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Affiliation(s)
- Meaghan E Ward
- Department of Physics, University of Guelph, Guelph, ON, Canada
- Biophysics Interdepartmental Group, University of Guelph, Guelph, ON, Canada
| | - Emily Ritz
- Department of Physics, University of Guelph, Guelph, ON, Canada
- Biophysics Interdepartmental Group, University of Guelph, Guelph, ON, Canada
| | - Mumdooh A M Ahmed
- Department of Physics, University of Guelph, Guelph, ON, Canada
- Biophysics Interdepartmental Group, University of Guelph, Guelph, ON, Canada
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON, Canada
- The Department of Physics, Faculty of Science, Suez University, Suez, 43533, Egypt
| | - Vladimir V Bamm
- Biophysics Interdepartmental Group, University of Guelph, Guelph, ON, Canada
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON, Canada
| | - George Harauz
- Biophysics Interdepartmental Group, University of Guelph, Guelph, ON, Canada
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON, Canada
| | - Leonid S Brown
- Department of Physics, University of Guelph, Guelph, ON, Canada
- Biophysics Interdepartmental Group, University of Guelph, Guelph, ON, Canada
| | - Vladimir Ladizhansky
- Department of Physics, University of Guelph, Guelph, ON, Canada.
- Biophysics Interdepartmental Group, University of Guelph, Guelph, ON, Canada.
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14
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Ramírez-Cordero B, Toledano Y, Cano-Sánchez P, Hernández-López R, Flores-Solis D, Saucedo-Yáñez AL, Chávez-Uribe I, Brieba LG, del Río-Portilla F. Cytotoxicity of recombinant tamapin and related toxin-like peptides on model cell lines. Chem Res Toxicol 2014; 27:960-7. [PMID: 24821061 DOI: 10.1021/tx4004193] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The scorpion toxin tamapin displays the most potent and selective blockage against KCa2.2 channels known to date. In this work, we report the biosynthesis, three-dimensional structure, and cytotoxicity on cancer cell lines (Jurkat E6-1 and human mammary breast cancer MDA-MB-231) of recombinant tamapin and five related peptides bearing mutations on residues (R6A,R7A, R13A, R6A-R7A, and GS-tamapin) that were previously suggested to be important for tamapin's activity. The indicated cell lines were used as they constitutively express KCa2.2 channels. The studied toxin-like peptides displayed lethal responses on Jurkat T cells and breast cancer cells; their effect is dose- and time-dependent with IC50 values in the nanomolar range. The order of potency is r-tamapin>GS-tamapin>R6A>R13A>R6A-R7A>R7A for Jurkat T cells and r-tamapin>R7A for MDA-MB-231 breast cancer cells. Our structural determination by NMR demonstrated that r-tamapin preserves the folding of the αKTx5 subfamily and that neither single nor double alanine mutations affect the three-dimensional structure of the wild-type peptide. In contrast, our activity assays show that changes in cytotoxicity are related to the chemical nature of certain residues. Our results suggest that the toxic activity of r-tamapin on Jurkat and breast cancer cells could be mediated by the interaction of charged residues in tamapin with KCa2.2 channels via the apoptotic cell death pathway.
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Affiliation(s)
- Belén Ramírez-Cordero
- Instituto de Química, Universidad Nacional Autónoma de México , Ciudad Universitaria, Circuito Exterior s/n, México, D.F. 04510, México
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15
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Rangarajan M, Aduse-Opoku J, Hashim A, Paramonov N, Curtis MA. Characterization of the α- and β-mannosidases of Porphyromonas gingivalis. J Bacteriol 2013; 195:5297-307. [PMID: 24056103 PMCID: PMC3837954 DOI: 10.1128/jb.00898-13] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2013] [Accepted: 09/13/2013] [Indexed: 11/20/2022] Open
Abstract
Mannose is an important sugar in the biology of the Gram-negative bacterium Porphyromonas gingivalis. It is a major component of the oligosaccharides attached to the Arg-gingipain cysteine proteases, the repeating units of an acidic lipopolysaccharide (A-LPS), and the core regions of both types of LPS produced by the organism (O-LPS and A-LPS) and a reported extracellular polysaccharide (EPS) isolated from spent culture medium. The organism occurs at inflamed sites in periodontal tissues, where it is exposed to host glycoproteins rich in mannose, which may be substrates for the acquisition of mannose by P. gingivalis. Five potential mannosidases were identified in the P. gingivalis W83 genome that may play a role in mannose acquisition. Four mannosidases were characterized in this study: PG0032 was a β-mannosidase, whereas PG0902 and PG1712 were capable of hydrolyzing p-nitrophenyl α-d-mannopyranoside. PG1711 and PG1712 were α-1 → 3 and α-1 → 2 mannosidases, respectively. No enzyme function could be assigned to PG0973. α-1 → 6 mannobiose was not hydrolyzed by P. gingivalis W50. EPS present in the culture supernatant was shown to be identical to yeast mannan and a component of the medium used for culturing P. gingivalis and was resistant to hydrolysis by mannosidases. Synthesis of O-LPS and A-LPS and glycosylation of the gingipains appeared to be unaffected in all mutants. Thus, α- and β-mannosidases of P. gingivalis are not involved in the harnessing of mannan/mannose from the growth medium for these biosynthetic processes. P. gingivalis grown in chemically defined medium devoid of carbohydrate showed reduced α-mannosidase activity (25%), suggesting these enzymes are environmentally regulated.
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Affiliation(s)
- Minnie Rangarajan
- Queen Mary University of London, Barts, and The London School of Medicine and Dentistry, Centre for Immunology and Infectious Disease, Blizard Institute, London, United Kingdom
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16
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Yu C, Chen CM. A Two-Dimensional1H NMR Approach for Peptide Backbone Assignments: Gramicidin S. J CHIN CHEM SOC-TAIP 2013. [DOI: 10.1002/jccs.198700047] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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17
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Lundström P, Ahlner A, Blissing AT. Isotope labeling methods for large systems. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2013; 992:3-15. [PMID: 23076576 DOI: 10.1007/978-94-007-4954-2_1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
A major drawback of nuclear magnetic resonance (NMR) spectroscopy compared to other methods is that the technique has been limited to relatively small molecules. However, in the last two decades the size limit has been pushed upwards considerably and it is now possible to use NMR spectroscopy for structure calculations of proteins of molecular weights approaching 100 kDa and to probe dynamics for supramolecular complexes of molecular weights in excess of 500 kDa. Instrumental for this progress has been development in instrumentation and pulse sequence design but also improved isotopic labeling schemes that lead to increased sensitivity as well as improved spectral resolution and simplification. These are described and discussed in this chapter, focusing on labeling schemes for amide proton and methyl proton detected experiments. We also discuss labeling methods for other potentially useful positions in proteins.
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Affiliation(s)
- Patrik Lundström
- Department of Physics, Chemistry and Biology, Linköping University, Linköping, Sweden.
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18
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Schmidt EY, Bidusenko IA, Protsuk NI, Ushakov IA, Trofimov BA. Superbase-Promoted Selective Cascade Cyclization Reaction of 1,5-Diketones with Acetylenes to Methylene-6,8-dioxabicyclo[3.2.1]octanes. European J Org Chem 2013. [DOI: 10.1002/ejoc.201201700] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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19
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Trofimov BA, Schmidt EY, Zorina NV, Ivanova EV, Ushakov IA. Transition-Metal-Free Superbase-Promoted Stereoselective α-Vinylation of Ketones with Arylacetylenes: A General Strategy for Synthesis of β,γ-Unsaturated Ketones. J Org Chem 2012; 77:6880-6. [DOI: 10.1021/jo301005p] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Boris A. Trofimov
- A. E. Favorsky
Irkutsk Institute of Chemistry, Siberian Branch, Russian Academy of Sciences, 1 Favorsky Str., 664033 Irkutsk,
Russia
| | - Elena Yu. Schmidt
- A. E. Favorsky
Irkutsk Institute of Chemistry, Siberian Branch, Russian Academy of Sciences, 1 Favorsky Str., 664033 Irkutsk,
Russia
| | - Nadezhda V. Zorina
- A. E. Favorsky
Irkutsk Institute of Chemistry, Siberian Branch, Russian Academy of Sciences, 1 Favorsky Str., 664033 Irkutsk,
Russia
| | - Elena V. Ivanova
- A. E. Favorsky
Irkutsk Institute of Chemistry, Siberian Branch, Russian Academy of Sciences, 1 Favorsky Str., 664033 Irkutsk,
Russia
| | - Igor' A. Ushakov
- A. E. Favorsky
Irkutsk Institute of Chemistry, Siberian Branch, Russian Academy of Sciences, 1 Favorsky Str., 664033 Irkutsk,
Russia
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20
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Gurrola GB, Hernández-López RA, Rodríguez de la Vega RC, Varga Z, Batista CVF, Salas-Castillo SP, Panyi G, del Río-Portilla F, Possani LD. Structure, function, and chemical synthesis of Vaejovis mexicanus peptide 24: a novel potent blocker of Kv1.3 potassium channels of human T lymphocytes. Biochemistry 2012; 51:4049-61. [PMID: 22540187 DOI: 10.1021/bi300060n] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Animal venoms are rich sources of ligands for studying ion channels and other pharmacological targets. Proteomic analyses of the soluble venom from the Mexican scorpion Vaejovis mexicanus smithi showed that it contains more than 200 different components. Among them, a 36-residue peptide with a molecular mass of 3864 Da (named Vm24) was shown to be a potent blocker of Kv1.3 of human lymphocytes (K(d) ∼ 3 pM). The three-dimensional solution structure of Vm24 was determined by nuclear magnetic resonance, showing the peptide folds into a distorted cystine-stabilized α/β motif consisting of a single-turn α-helix and a three-stranded antiparallel β-sheet, stabilized by four disulfide bridges. The disulfide pairs are formed between Cys6 and Cys26, Cys12 and Cys31, Cys16 and Cys33, and Cys21 and Cys36. Sequence analyses identified Vm24 as the first example of a new subfamily of α-type K(+) channel blockers (systematic number α-KTx 23.1). Comparison with other Kv1.3 blockers isolated from scorpions suggests a number of structural features that could explain the remarkable affinity and specificity of Vm24 toward Kv1.3 channels of lymphocytes.
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Affiliation(s)
- Georgina B Gurrola
- Departamento de Medicina Molecular y Bioprocesos, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Av. Universidad, 2001 Cuernavaca, Mor. 62210, Mexico
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21
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Krähenbühl B, Hiller S, Wider G. 4D APSY-HBCB(CG)CDHD experiment for automated assignment of aromatic amino acid side chains in proteins. JOURNAL OF BIOMOLECULAR NMR 2011; 51:313-318. [PMID: 21947871 DOI: 10.1007/s10858-011-9572-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/27/2011] [Accepted: 08/06/2011] [Indexed: 05/31/2023]
Abstract
A four-dimensional (4D) APSY (automated projection spectroscopy)-HBCB(CG)CDHD experiment is presented. This 4D experiment correlates aromatic with aliphatic carbon and proton resonances from the same amino acid side chain of proteins in aqueous solution. It thus allows unambiguous sequence-specific assignment of aromatic amino acid ring signals based on backbone assignments. Compared to conventional 2D approaches, the inclusion of evolution periods on (1)H(β) and (13)C(δ) efficiently removes overlaps, and provides two additional frequencies for consequent automated or manual matching. The experiment was successfully applied to three proteins with molecular weights from 6 to 13 kDa. For the complementation of the assignment of the aromatic resonances, TOCSY- or COSY-based versions of a 4D APSY-HCCH(aro) sequence are proposed.
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Affiliation(s)
- Barbara Krähenbühl
- Institute of Molecular Biology and Biophysics, ETH Zurich, 8093 Zurich, Switzerland
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22
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Jurkowski W, Kułaga T, Roterman I. Geometric parameters defining the structure of proteins--relation to early-stage folding step. J Biomol Struct Dyn 2011; 29:79-104. [PMID: 21696227 DOI: 10.1080/07391102.2011.10507376] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
Two geometrical parameters describing the structure of a polypeptide: V-dihedral angle between two sequential peptide bond planes and R-radius of curvature are used for structural classification of polypeptide structure in proteins. The relation between these two parameters was the basis for the definition of the conformational sub-space for early-stage structural forms. The cluster analysis of V and lnR, applied to the selected proteins of well-defined secondary structure (according to DSSP classification) and to proteins without any introductory classified analysis, revealed that several of the discriminated groups of proteins agree with the assumed model of early-stage conformational sub-space. This analysis shows that protein structures may be represented in VR space instead of Phi, Psi angles space, thus lowering the conformational space dimensionality. The VR model allows classification of traditional secondary structure elements as well as different Random Coil motifs, which broadens the range of recognized structural categories (compared to standard secondary structure elements).
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Affiliation(s)
- W Jurkowski
- Department of Bioinformatics and Telemedicine, Jagiellonian University-Medical College, Department of Bioinformatics and Telemedicine, Lazarza 16, 31-530 Krakow, Poland
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23
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Miao L, Qin H, Koehl P, Song J. Selective and specific ion binding on proteins at physiologically-relevant concentrations. FEBS Lett 2011; 585:3126-32. [PMID: 21907714 DOI: 10.1016/j.febslet.2011.08.048] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2011] [Revised: 08/25/2011] [Accepted: 08/29/2011] [Indexed: 12/13/2022]
Abstract
Insoluble proteins dissolved in unsalted water appear to have no well-folded tertiary structures. This raises a fundamental question as to whether being unstructured is due to the absence of salt ions. To address this issue, we solubilized the insoluble ephrin-B2 cytoplasmic domain in unsalted water and first confirmed using NMR spectroscopy that it is only partially folded. Using NMR HSQC titrations with 14 different salts, we further demonstrate that the addition of salt triggers no significant folding of the protein within physiologically relevant ion concentrations. We reveal however that their 8 anions bind to the ephrin-B2 protein with high affinity and specificity at biologically-relevant concentrations. Interestingly, the binding is found to be both salt- and residue-specific.
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Affiliation(s)
- Linlin Miao
- Department of Biological Sciences, Faculty of Science, National University of Singapore, Singapore
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24
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Schmidt JM, Zhou S, Rowe ML, Howard MJ, Williamson RA, Löhr F. One-bond and two-bond J couplings help annotate protein secondary-structure motifs: J-coupling indexing applied to human endoplasmic reticulum protein ERp18. Proteins 2011; 79:428-43. [PMID: 21117079 DOI: 10.1002/prot.22893] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
NMR coupling constants, both direct one-bond ((1)J) and geminal two-bond ((2)J), are employed to analyze the protein secondary structure of human oxidized ERp18. Coupling constants collected and evaluated for the 18 kDa protein comprise 1268 values of (1)J(CαHα), (1)J(CαCβ), (1)J(CαC'), (1)J(C'N'), (1)J(N'Cα), (1)J(N') (HN), (2)J(CαN'), (2)J(HNCα), (2)J(C'HN), and (2)J(HαC'). Comparison with (1)J and (2)J data from reference proteins and pattern analysis on a per-residue basis permitted main-chain ϕ,ψ torsion-angle combinations of many of the 149 amino-acid residues in ERp18 to be narrowed to particular secondary-structure motifs. J-coupling indexing is here being developed on statistical criteria and used to devise a ternary grid for interpreting patterns of relative values of J. To account for the influence of the varying substituent pattern in different amino-acid sidechains, a table of residue-type specific threshold values was compiled for discriminating small, medium, and large categories of J. For the 15-residue insertion that distinguishes the ERp18 fold from that of thioredoxin, the J-coupling data hint at a succession of five isolated Type-I β turns at progressively shorter sequence intervals, in agreement with the crystal structure.
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Affiliation(s)
- Jürgen M Schmidt
- School of Biosciences, University of Kent, Canterbury, Kent CT2 7NJ, United Kingdom.
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25
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Crimmins DL, Kao JLF. A 68 residue N-terminal fragment of pro-atrial natriuretic peptide is a monomeric intrinsically unstructured protein. ACTA ACUST UNITED AC 2011; 150:157-63. [DOI: 10.1093/jb/mvr046] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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26
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Esnouf P, Lawrence MP, Mabbutt BC, Patthy L, Pluck N, Williams RJP. The Outline Structure of Protein Domains Called Kringles. ACTA ACUST UNITED AC 2010. [DOI: 10.1002/bscb.19850941116] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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27
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RIGHI VALERIA, APIDIANAKIS YIORGOS, MINTZOPOULOS DIONYSSIOS, ASTRAKAS LOUKAS, RAHME LAURENCEG, TZIKA AARIA. In vivo high-resolution magic angle spinning magnetic resonance spectroscopy of Drosophila melanogaster at 14.1 T shows trauma in aging and in innate immune-deficiency is linked to reduced insulin signaling. Int J Mol Med 2010; 26:175-84. [PMID: 20596596 PMCID: PMC3722717 DOI: 10.3892/ijmm_00000450] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2010] [Accepted: 03/12/2010] [Indexed: 01/07/2023] Open
Abstract
In vivo magnetic resonance spectroscopy (MRS), a non-destructive biochemical tool for investigating live organisms, has yet to be used in the fruit fly Drosophila melanogaster, a useful model organism for investigating genetics and physiology. We developed and implemented a high-resolution magic-angle-spinning (HRMAS) MRS method to investigate live Drosophila at 14.1 T. We demonstrated, for the first time, the feasibility of using HRMAS MRS for molecular characterization of Drosophila with a conventional MR spectrometer equipped with an HRMAS probe. We showed that the metabolic HRMAS MRS profiles of injured, aged wild-type (wt) flies and of immune deficient (imd) flies were more similar to chico flies mutated at the chico gene in the insulin signaling pathway, which is analogous to insulin receptor substrate1-4 (IRS1-4) in mammals and less to those of adipokinetic hormone receptor (akhr) mutant flies, which have an obese phenotype. We thus provide evidence for the hypothesis that trauma in aging and in innate immune-deficiency is linked to insulin signaling. This link may explain the mitochondrial dysfunction that accompanies insulin resistance and muscle wasting that occurs in trauma, aging and immune system deficiencies, leading to higher susceptibility to infection. Our approach advances the development of novel in vivo non-destructive research approaches in Drosophila, suggests biomarkers for investigation of biomedical paradigms, and thus may contribute to novel therapeutic development.
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Affiliation(s)
- VALERIA RIGHI
- NMR Surgical Laboratory, Department of Surgery, Massachusetts General Hospital and Shriners Burn Institute, Harvard Medical School
- Athinoula A. Martinos Center of Biomedical Imaging, Department of Radiology, Massachusetts General Hospital
| | - YIORGOS APIDIANAKIS
- NMR Surgical Laboratory, Department of Surgery, Massachusetts General Hospital and Shriners Burn Institute, Harvard Medical School
- Molecular Surgery Laboratory, Department of Surgery, Massachusetts General Hospital, Boston, MA 02114,
USA
| | - DIONYSSIOS MINTZOPOULOS
- NMR Surgical Laboratory, Department of Surgery, Massachusetts General Hospital and Shriners Burn Institute, Harvard Medical School
- Athinoula A. Martinos Center of Biomedical Imaging, Department of Radiology, Massachusetts General Hospital
| | - LOUKAS ASTRAKAS
- NMR Surgical Laboratory, Department of Surgery, Massachusetts General Hospital and Shriners Burn Institute, Harvard Medical School
- Athinoula A. Martinos Center of Biomedical Imaging, Department of Radiology, Massachusetts General Hospital
| | - LAURENCE G. RAHME
- Molecular Surgery Laboratory, Department of Surgery, Massachusetts General Hospital, Boston, MA 02114,
USA
| | - A. ARIA TZIKA
- NMR Surgical Laboratory, Department of Surgery, Massachusetts General Hospital and Shriners Burn Institute, Harvard Medical School
- Athinoula A. Martinos Center of Biomedical Imaging, Department of Radiology, Massachusetts General Hospital
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28
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Synthesis and structural study of N-methyl-2-methylthiopyrimidine derivatives from trihalomethylated enones. J Heterocycl Chem 2010. [DOI: 10.1002/jhet.425] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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29
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Salgado GF, Marquant R, Vogel A, Alves ID, Feller SE, Morellet N, Bouaziz S. Structural studies of HIV-1 Gag p6ct and its interaction with Vpr determined by solution nuclear magnetic resonance. Biochemistry 2010; 48:2355-67. [PMID: 19254034 DOI: 10.1021/bi801794v] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The ability of human immunodeficiency virus type 1 (HIV-1) to egress from human cells by budding with the cell membrane remains a complex phenomenon of unclear steps. HIV-1 viral protein R (Vpr) incorporation in sorting virions relies greatly on the interaction with the group-specific antigen (Gag) C-terminal region, which encompasses protein p6. The complete role of p6 is still undetermined; however, it is thought that p6 interacts with protein core elements from the endosomal sorting complex ESCRT-1, known to sort ubiquitinated cargo into multivesicular bodies (MVB). The three-dimensional structure of the p6 C-terminus (p6ct) comprising amino acids 32-52, determined in this study using NMR methods, includes the region thought to interact with Vpr, i.e., the LXXLF sequence. Here we present new results indicating that the region which interacts with Vpr is the ELY(36) sequence, in the same region where mutational studies revealed that replacing Y36 with a phenylalanine would increase the infectivity of virions by 300-fold. The interaction of Vpr with an egg PC bilayer in the presence of p6ct measured by plasmon waveguide resonance (PWR) is approximately 0.8 microM, approximately 100 times stronger in the absence of p6ct. Our results suggests an interaction based on an ELYP(37) sequence bearing similarities with recently published results, which elegantly demonstrated that the HIV-1 Gag LYPx(n)LxxL motif interacts with Alix 364-702. Moreover, we performed a 60 ns molecular dynamics (MD) simulation of p6ct in DPC micelles. The MD results, supported by differential scanning calorimetry measurements in DMPC, show that p6ct adsorbs onto the DPC micelle surface by adopting a rather stable alpha-helix. Our results provide insights regarding the HIV-1 virion sorting mechanism, specifically concerning the interaction between p6 and Vpr. We also suggest that Gag p6 may adsorb onto the surface of membranes during the sorting process, a property so far only attributed to the N-terminal portion of Gag matrix (MA), which is myristylated. The implications of such a novel event provide an alternative direction toward understanding the assembly and escape mechanisms of virions, which have been undetected so far.
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Affiliation(s)
- Gilmar F Salgado
- Unité de Pharmacologie Chimique et Génétique, Inserm U640, CNRS UMR8151, UFR des Sciences Pharmaceutiques et Biologiques, 4, avenue de l'Observatoire, 75270 Paris Cedex 06, France.
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30
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Pivnenko NS, Turov AV, Abakumov VV, Kutulya LA, Shishkina SV, Shishkin OV. Molecular structures of regioisomeric 7-arylidene hexahydroindazoles from (1)H NMR spectra. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2009; 47:488-496. [PMID: 19267426 DOI: 10.1002/mrc.2421] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
The structural characterization of two regioisomeric products of the interaction of 2,6-bis-(4-methoxybenzylidene)-3R-methylcyclohexanone with methyl hydrazine was achieved using (1)H NMR spectral data, including chemical shifts, coupling constants and results of COSY and nuclear overhauser effect (NOE) experiments. Configurations of the new chiral centers in the (3S,3aR,6R,7E)-7-(4-methoxybenzylidene)-3,4,5,7-hexahydro-3-(4-methoxyphenyl)-2,6-dimethyl- and 2,4-dimethyl-2H-indazoles were assigned on the basis of experimental data combined with molecular modeling by the density functional theory (DFT) method. The distinction in the helical twisting power of studied compounds under addition to a nematic liquid crystal is discussed on the basis of peculiarities of the molecular structures.
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Affiliation(s)
- Nikolay S Pivnenko
- STC Institute for Single Crystals, National Academy of Sciences of Ukraine, 60 Lenin Ave, Kharkov, 61001 Ukraine.
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31
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Zanatta N, Madruga CC, Marisco PC, Da Rosa LS, Fernandes LDS, Flores DC, Flores AFC, Burrow RA, Bonacorso HG, Martins MAP. Synthesis and structural study of a new series of 2‐methylsulfanyl‐tetrahydropyrimidines from β‐alkoxyvinyl trihalomethyl ketones. J Heterocycl Chem 2009. [DOI: 10.1002/jhet.5570450127] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Nilo Zanatta
- Núcleo de Química de Heterociclos (NUQUIMHE), Departamento de Química, Universidade Federal de Santa Maria, 97.105–900, Santa Maria, RS, Brazil
| | - Claudia C. Madruga
- Núcleo de Química de Heterociclos (NUQUIMHE), Departamento de Química, Universidade Federal de Santa Maria, 97.105–900, Santa Maria, RS, Brazil
| | - Patricia C. Marisco
- Núcleo de Química de Heterociclos (NUQUIMHE), Departamento de Química, Universidade Federal de Santa Maria, 97.105–900, Santa Maria, RS, Brazil
| | - Luciana S. Da Rosa
- Núcleo de Química de Heterociclos (NUQUIMHE), Departamento de Química, Universidade Federal de Santa Maria, 97.105–900, Santa Maria, RS, Brazil
| | - Liana Da S. Fernandes
- Núcleo de Química de Heterociclos (NUQUIMHE), Departamento de Química, Universidade Federal de Santa Maria, 97.105–900, Santa Maria, RS, Brazil
| | - Darlene C. Flores
- Núcleo de Química de Heterociclos (NUQUIMHE), Departamento de Química, Universidade Federal de Santa Maria, 97.105–900, Santa Maria, RS, Brazil
| | - Alex F. C. Flores
- Núcleo de Química de Heterociclos (NUQUIMHE), Departamento de Química, Universidade Federal de Santa Maria, 97.105–900, Santa Maria, RS, Brazil
| | - Robert A. Burrow
- Núcleo de Química de Heterociclos (NUQUIMHE), Departamento de Química, Universidade Federal de Santa Maria, 97.105–900, Santa Maria, RS, Brazil
| | - Helio G. Bonacorso
- Núcleo de Química de Heterociclos (NUQUIMHE), Departamento de Química, Universidade Federal de Santa Maria, 97.105–900, Santa Maria, RS, Brazil
| | - Marcos A P. Martins
- Núcleo de Química de Heterociclos (NUQUIMHE), Departamento de Química, Universidade Federal de Santa Maria, 97.105–900, Santa Maria, RS, Brazil
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33
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Harvey AL, Anderson AJ, Mbugua PM, Karlsson E. Toxins from Mamba Venoms that Facilitate Neuroiluscular Transmission. ACTA ACUST UNITED AC 2008. [DOI: 10.3109/15569548409097923] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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34
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NMR evidence for forming highly populated helical conformations in the partially folded hNck2 SH3 domain. Biophys J 2008; 95:4803-12. [PMID: 18599634 DOI: 10.1529/biophysj.107.125641] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Recent studies of several proteins implied that the folding of beta-proteins may follow a nonhierarchical mechanism in which two major transitions are essential, i.e., the collapse of a random coil to form a nonnative helical intermediate, followed by a transformation into the native beta-structure. We report that the first hNck2 SH3 domain, assuming an all-beta barrel in the native form, can be reversibly transformed into a stable and nonnative helical state by acid-unfolding. We also conducted extensive NMR and mutagenesis studies that led to two striking findings: 1), NMR analysis reveals that in the helical state formed at pH 2.0, the first and last beta-strands in the native form become unstructured, whereas the rest is surprisingly converted into two highly populated helices with a significantly limited backbone motion; and 2), a conserved four-residue sequence is identified on the second beta-strand, a mutation of which suddenly renders the SH3 domain into a helical state even at pH 6.5, with NMR conformational and dynamic properties highly similar to those of the wild-type at pH 2.0. This observation implies that the region might contribute key interactions to disrupt the helical state, and to facilitate a further transformation into the native SH3 fold in the second transition.
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35
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Li M, Li Y, Liao X, Liu J, Qin H, Xiao ZC, Song J. Rational design, solution conformation and identification of functional residues of the soluble and structured Nogo-54, which mimics Nogo-66 in inhibiting the CNS neurite outgrowth. Biochem Biophys Res Commun 2008; 373:498-503. [PMID: 18585367 DOI: 10.1016/j.bbrc.2008.06.052] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2008] [Accepted: 06/13/2008] [Indexed: 10/21/2022]
Abstract
The interaction between Nogo-66 and its receptor NgR represents a promising target for designing drugs to treat CNS axonal injury which often leads to permanent disability. Unfortunately, the isolated Nogo-66 is highly insoluble while its truncated form Nogo-40 is soluble but unstructured, thus retarding further characterization and application. Here, we rationally design another soluble form Nogo-54. CD and NMR characterization reveals that Nogo-54 is structured, and importantly, is able to mimic Nogo-66 in inhibiting neurite outgrowth. Strikingly, mutating its C-terminal four residues (Lys50, Glu51, Arg53, and Arg54) leads to a mutant Nogo-54m which has no dramatic structural change but whose inhibitory activity is completely abolished. This strongly suggests that the four charged residues contribute significantly to the inhibitory action of Nogo-66. Furthermore, our study also provides a soluble and structured mimic as well as a possible antagonist for Nogo-66 which may hold promising potential for various medical applications.
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Affiliation(s)
- Minfen Li
- Department of Biological Sciences, Faculty of Science, National University of Singapore, Singapore
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Scheidt HA, Huster D. The interaction of small molecules with phospholipid membranes studied by 1H NOESY NMR under magic-angle spinning. Acta Pharmacol Sin 2008; 29:35-49. [PMID: 18158864 DOI: 10.1111/j.1745-7254.2008.00726.x] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
The interaction of small molecules with lipid membranes and the exact knowledge of their binding site and bilayer distribution is of great pharmacological importance and represents an active field of current biophysical research. Over the last decade, a highly resolved 1H solid-state NMR method has been developed that allows measuring localization and distribution of small molecules in membranes. The classical solution 1H NMR NOESY technique is applied to lipid membrane samples under magic-angle spinning (MAS) and NOESY cross-relaxation rates are determined quantitatively. These rates are proportional to the contact probability between molecular segments and therefore an ideal tool to study intermolecular interactions in membranes. Here, we review recent 1H MAS NOESY applications that were carried out to study lateral lipid organization in mixed membranes and the interaction of membranes with water, ethanol, small aromatic compounds, peptides, fluorescence labels, and lipophilic nucleosides.
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Ferrari E, Grandi R, Lazzari S, Marverti G, Rossi MC, Saladini M. 1H, 13C, 195Pt NMR study on platinum(II) interaction with sulphur containing Amadori compounds. Polyhedron 2007. [DOI: 10.1016/j.poly.2007.05.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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39
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Zhong L, Bamm VV, Ahmed MAM, Harauz G, Ladizhansky V. Solid-state NMR spectroscopy of 18.5 kDa myelin basic protein reconstituted with lipid vesicles: spectroscopic characterisation and spectral assignments of solvent-exposed protein fragments. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2007; 1768:3193-205. [PMID: 17920035 DOI: 10.1016/j.bbamem.2007.08.013] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/25/2007] [Revised: 08/10/2007] [Accepted: 08/10/2007] [Indexed: 10/22/2022]
Abstract
Myelin basic protein (MBP, 18.5 kDa isoform) is a peripheral membrane protein that is essential for maintaining the structural integrity of the multilamellar myelin sheath of the central nervous system. Reconstitution of the most abundant 18.5 kDa MBP isoform with lipid vesicles yields an aggregated assembly mimicking the protein's natural environment, but which is not amenable to standard solution NMR spectroscopy. On the other hand, the mobility of MBP in such a system is variable, depends on the local strength of the protein-lipid interaction, and in general is of such a time scale that the dipolar interactions are averaged out. Here, we used a combination of solution and solid-state NMR (ssNMR) approaches: J-coupling-driven polarization transfers were combined with magic angle spinning and high-power decoupling to yield high-resolution spectra of the mobile fragments of 18.5 kDa murine MBP in membrane-associated form. To partially circumvent the problem of short transverse relaxation, we implemented three-dimensional constant-time correlation experiments (NCOCX, NCACX, CONCACX, and CAN(CO)CX) that were able to provide interresidue and intraresidue backbone correlations. These experiments resulted in partial spectral assignments for mobile fragments of the protein. Additional nuclear Overhauser effect spectroscopy (NOESY)-based experiments revealed that the mobile fragments were exposed to solvent and were likely located outside the lipid bilayer, or in its hydrophilic portion. Chemical shift index analysis showed that the fragments were largely disordered under these conditions. These combined approaches are applicable to ssNMR investigations of other peripheral membrane proteins reconstituted with lipids.
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Affiliation(s)
- Ligang Zhong
- Department of Physics, University of Guelph, 50 Stone Road East, Guelph, Ontario, Canada N1G 2W1
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40
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Trofimov BA, Sobenina LN, Mikhaleva AI, Petrova OV, Drichkov VN, Ushakov IA, Tarasova OA, Toryashinova DSD, Rusakov YY, Krivdin LB. Facile coupling of 2-(1-ethylthioethenyl)pyrroles with amines: A route to 2-(1-aminoethenyl)pyrroles and 1-amino-3-iminopyrrolizines. J Heterocycl Chem 2007. [DOI: 10.1002/jhet.5570440301] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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41
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Lee YC, Jackson PL, Jablonsky MJ, Muccio DD. Conformation of 3'CMP bound to RNase A using TrNOESY. Arch Biochem Biophys 2007; 463:37-46. [PMID: 17416340 DOI: 10.1016/j.abb.2007.02.034] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2007] [Accepted: 02/09/2007] [Indexed: 11/30/2022]
Abstract
The conditions for accurately determining distance constraints from TrNOESY data on a small ligand (3'CMP) bound to a small protein (RNase A, <14 kDa) are described. For small proteins, normal TrNOESY conditions of 10:1 ligand:protein or greater can lead to inaccurate structures for the ligand-bound conformation due to the contribution of the free ligand to the TrNOESY signals. By using two ligand:protein ratios (2:1 and 5:1), which give the same distance constraints, a conformation of 3'CMP bound to RNase A was determined (glycosidic torsion angle, chi=-166 degrees ; pseudorotational phase angle, 0 degrees < or = P < or =36 degrees ). Ligand-protein NOESY cross peaks were also observed and used to dock 3'CMP into the binding pocket of the apo-protein (7rsa). After energy minimization, the conformation of the 3'CMP:RNase A complex was similar to the X-ray structure (1 rpf) except that a C3'-endo conformation for the ribose ring (rather than C2'-exo conformation) was found in the TrNOESY structure.
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Affiliation(s)
- Yi-Chien Lee
- National Cancer Institute at Frederick, Laboratory of Medical Chemistry, 376 Boyles Street, Building 376, Frederick, MD 21702, USA
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Munowitz M, Pines A. Principles and Applications of Multiple-Quantum Nmr. ADVANCES IN CHEMICAL PHYSICS 2007. [DOI: 10.1002/9780470142929.ch1] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/17/2023]
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Löhr F, Hänsel R, Rogov VV, Dötsch V. Improved pulse sequences for sequence specific assignment of aromatic proton resonances in proteins. JOURNAL OF BIOMOLECULAR NMR 2007; 37:205-24. [PMID: 17237975 DOI: 10.1007/s10858-006-9128-4] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/08/2006] [Accepted: 11/23/2006] [Indexed: 05/13/2023]
Abstract
Aromatic proton resonances of proteins are notoriously difficult to assign. Through-bond correlation experiments are preferable over experiments that rely on through-space interactions because they permit aromatic chemical shift assignments to be established independently of the structure determination process. Known experimental schemes involving a magnetization transfer across the Cbeta-Cgamma bond in aromatic side chains either suffer from low efficiency for the relay beyond the Cdelta position, use sophisticated 13C mixing schemes, require probe heads suitable for application of high 13C radio-frequency fields or rely on specialized isotopic labelling patterns. Novel methods are proposed that result in sequential assignment of all aromatic protons in uniformly 13C/15N labelled proteins using standard spectrometer hardware. Pulse sequences consist of routinely used building blocks and are therefore reasonably simple to implement. Ring protons may be correlated with beta-carbons and, alternatively, with amide protons (and nitrogens) or carbonyls in order to take advantage of the superior dispersion of backbone resonances. It is possible to record spectra in a non-selective manner, yielding signals of all aromatic residues, or as amino-acid type selective versions to further reduce ambiguities. The new experiments are demonstrated with four different proteins with molecular weights ranging from 11 kDa to 23 kDa. Their performance is compared with that of (Hbeta)Cbeta(CgammaCdelta)Hdelta and (Hbeta)Cbeta(CgammaCdeltaCepsilon)Hepsilon pulse sequences.
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Affiliation(s)
- Frank Löhr
- Institute of Biophysical Chemistry, Centre for Biomolecular Magnetic Resonance, Johann Wolfgang Goethe-University, Frankfurt, Germany.
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44
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Lescot E, Sopkova-de Oliveira Santos J, Dubessy C, Oulyadi H, Lesnard A, Vaudry H, Bureau R, Rault S. Definition of New Pharmacophores for Nonpeptide Antagonists of Human Urotensin-II. Comparison with the 3D-structure of Human Urotensin-II and URP. J Chem Inf Model 2007; 47:602-12. [PMID: 17381176 DOI: 10.1021/ci6003948] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Starting from nonpeptide agonists and antagonists of human urotensin-II (hU-II), several pharmacophores were designed and compared to the structure of hU-II. NMR and dynamic studies were realized on hU-II and urotensin-II-related peptide to check the conformation flexibilities of these peptides and the relationships between their potential 3D structures and the pharmacophores. In parallel, a virtual screening was carried out, leading to the discovery of six new derivatives with micromolar affinities. This last result shows the interest of these pharmacophores for the discovery of new ligands.
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Affiliation(s)
- Elodie Lescot
- Centre d'Etudes et de Recherche sur le Médicament de Normandie, Université de Caen, U.F.R. des Sciences Pharmaceutiques, 5 rue Vaubénard, 14032 Caen Cedex, France
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Xu Y, Zheng Y, Fan JS, Yang D. A new strategy for structure determination of large proteins in solution without deuteration. Nat Methods 2007; 3:931-7. [PMID: 17060917 DOI: 10.1038/nmeth938] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2006] [Accepted: 08/08/2006] [Indexed: 11/09/2022]
Abstract
So far high-resolution structure determination by nuclear magnetic resonance (NMR) spectroscopy has been limited to proteins <30 kDa, although global fold determination is possible for substantially larger proteins. Here we present a strategy for assigning backbone and side-chain resonances of large proteins without deuteration, with which one can obtain high-resolution structures from (1)H-(1)H distance restraints. The strategy uses information from through-bond correlation experiments to filter intraresidue and sequential correlations from through-space correlation experiments, and then matches the filtered correlations to obtain sequential assignment. We demonstrate this strategy on three proteins ranging from 24 to 65 kDa for resonance assignment and on maltose binding protein (42 kDa) and hemoglobin (65 kDa) for high-resolution structure determination. The strategy extends the size limit for structure determination by NMR spectroscopy to 42 kDa for monomeric proteins and to 65 kDa for differentially labeled multimeric proteins without the need for deuteration or selective labeling.
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Affiliation(s)
- Yingqi Xu
- Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, Singapore 117543
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Bock JL. Recent developments in biochemical nuclear magnetic resonance spectroscopy. METHODS OF BIOCHEMICAL ANALYSIS 2006; 31:259-315. [PMID: 3894882 DOI: 10.1002/9780470110522.ch6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
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Li M, Liu J, Song J. Nogo goes in the pure water: solution structure of Nogo-60 and design of the structured and buffer-soluble Nogo-54 for enhancing CNS regeneration. Protein Sci 2006; 15:1835-41. [PMID: 16877707 PMCID: PMC2242580 DOI: 10.1110/ps.062306906] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
The inability to determine the structure of the buffer-insoluble Nogo extracellular domain retarded further design of Nogo receptor (NgR) antagonists to treat CNS axonal injuries. Very surprisingly, we recently discovered that Nogo-60 was soluble and structured in salt-free water, thus allowing the determination of the first Nogo structure by heteronuclear NMR spectroscopy. Nogo-60 adopts an unusual helical structure with the N- and C-terminal helices connected by a long middle helix. While the N-helix has no contact with the rest of the molecule, the C-helix flips back to pack against the 20-residue middle helix. This packing appears to trigger the formation of the stable Nogo-60 structure because Nogo-40 with the last helix truncated is unstructured. The Nogo-60 structure offered us rationales for further design of the structured and buffer-soluble Nogo-54, which may be used as a novel NgR antagonist. Furthermore, our discovery may imply a general solution to solubilizing a category of buffer-insoluble proteins for urgent structural investigations.
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Affiliation(s)
- Minfen Li
- Department of Biological Sciences, Faculty of Science, National University of Singapore, Singapore
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Trofimov BA, Sobenina LN, Stepanova ZV, Demenev AP, Mikhaleva AI, Ushakov IA, Vakul’skaya TI, Petrova OV. Synthesis of 2-benzoylethynylpyrroles by cross coupling of 2-arylpyrroles with 1-benzoyl-2-bromoacetylene over aluminum oxide. RUSSIAN JOURNAL OF ORGANIC CHEMISTRY 2006. [DOI: 10.1134/s1070428006090168] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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49
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Trofimov BA, Petrova OV, Sobenina LN, Drichkov VN, Mikhaleva AI, Ushakov IA, Tarasova OA, Kazheva ON, Chekhlov AN, Dyachenko OA. Vinylic nucleophilic substitution in functionalized 2-vinylpyrroles: a route to a new family of stable enols. Tetrahedron 2006. [DOI: 10.1016/j.tet.2006.02.009] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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50
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