1
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Graf C, Stollberger R, Rund A, Schweiger M, Diwoky C. Robust dual-angle T 1 measurement in magnetization transfer spectroscopy by time-optimal control. NMR IN BIOMEDICINE 2024; 37:e5151. [PMID: 38583871 DOI: 10.1002/nbm.5151] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/13/2023] [Revised: 02/07/2024] [Accepted: 03/01/2024] [Indexed: 04/09/2024]
Abstract
Magnetization transfer spectroscopy relies heavily on the robust determination ofT 1 relaxation times of nuclei participating in metabolic exchange. Challenges arise due to the use of surface RF coils for transmission (highB 1 + variation) and the broad resonance band of most X nuclei. These challenges are particularly pronounced when fastT 1 mapping methods, such as the dual-angle method, are employed. Consequently, in this work, we develop resonance offset andB 1 + robust excitation RF pulses for 31P magnetization transfer spectroscopy at 7T through ensemble-based time-optimal control. In our approach, we introduce a cost functional for designing robust pulses, incorporating the full Bloch equations as constraints, which are solved using symmetric operator splitting techniques. The optimal control design of the RF pulses developed demonstrates improved accuracy, desired phase properties, and reduced RF power when applied to dual-angleT 1 mapping, thereby improving the precision of exchange-rate measurements, as demonstrated in a preclinical in vivo study quantifying brain creatine kinase activity.
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Affiliation(s)
- Christina Graf
- Institute of Biomedical Imaging, Graz University of Technology, Graz, Austria
- Department of Pediatrics, University of British Columbia, Vancouver, BC, Canada
| | - Rudolf Stollberger
- Institute of Biomedical Imaging, Graz University of Technology, Graz, Austria
- BioTechMed-Graz, Graz, Austria
| | - Armin Rund
- Institute for Mathematics and Scientific Computing, Karl-Franzens University Graz, Graz, Austria
| | - Martina Schweiger
- BioTechMed-Graz, Graz, Austria
- Institute of Molecular Biosciences, Karl-Franzens University Graz, Graz, Austria
- Field of Excellence BioHealthKarl-Franzens University Graz, Graz, Austria
| | - Clemens Diwoky
- Institute of Molecular Biosciences, Karl-Franzens University Graz, Graz, Austria
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2
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Sager E, Tzvetkova P, Lingel A, Gossert AD, Luy B. Hydrogen bond formation may enhance RDC-based discrimination of enantiomers. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2024; 62:639-647. [PMID: 38785031 DOI: 10.1002/mrc.5448] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/28/2024] [Revised: 03/28/2024] [Accepted: 04/08/2024] [Indexed: 05/25/2024]
Abstract
The distinction of enantiomers based on residual anisotropic parameters obtained by alignment in chiral poly-γ-benzyl-L-glutamate (PBLG) is among the strongest in high-resolution NMR spectroscopy. However, large variations in enantiodifferentiation among different solutes are frequently observed. One hypothesis is that the formation of hydrogen bonds between solute and PBLG is important for the distinction of enantiomers. With a small set of three almost spherical enantiomeric pairs, for which 1DCH residual dipolar couplings are measured, we address this issue in a systematic way: borneol contains a single functional group that can act as a hydrogen bond donor, camphor has a single group that may act as a hydrogen bond acceptor, and quinuclidinol can act as both hydrogen bond donor and acceptor. The results are unambiguous: although camphor shows low enantiodifferentiation with PBLG and alignment that can be predicted well by the purely steric TRAMITE approach, the distinction of enantiomers for the other enantiomeric pairs is significantly higher with alignment properties that must involve a specific interaction in addition to steric alignment.
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Affiliation(s)
- Emine Sager
- Institute of Organic Chemistry and Institute for Biological Interfaces 4-Magnetic Resonance, Karlsruhe Institute of Technology (KIT), Eggenstein-Leopoldshafen, Germany
- Novartis Biomedical Research, Basel, Switzerland
| | - Pavleta Tzvetkova
- Institute of Organic Chemistry and Institute for Biological Interfaces 4-Magnetic Resonance, Karlsruhe Institute of Technology (KIT), Eggenstein-Leopoldshafen, Germany
| | | | | | - Burkhard Luy
- Institute of Organic Chemistry and Institute for Biological Interfaces 4-Magnetic Resonance, Karlsruhe Institute of Technology (KIT), Eggenstein-Leopoldshafen, Germany
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3
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Joseph D, Griesinger C. Optimal control pulses for the 1.2-GHz (28.2-T) NMR spectrometers. SCIENCE ADVANCES 2023; 9:eadj1133. [PMID: 37948513 PMCID: PMC10637738 DOI: 10.1126/sciadv.adj1133] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2023] [Accepted: 10/12/2023] [Indexed: 11/12/2023]
Abstract
The ability to measure nuclear magnetic resonance (NMR) spectra with a large sample volume is crucial for concentration-limited biological samples to attain adequate signal-to-noise (S/N) ratio. The possibility to measure with a 5-mm cryoprobe is currently absent at the 1.2-GHz NMR instruments due to the exceedingly high radio frequency power demands, which is four times compared to 600-MHz instruments. Here, we overcome the high-power demands by designing optimal control (OC) pulses with up to 20 times lower power requirements than currently necessary at a 1.2-GHz spectrometer. We show that multidimensional biomolecular NMR experiments constructed using these OC pulses can bestow improvement in the S/N ratio of up to 26%. With the expected power limitations of a 5-mm cryoprobe, we observe an enhancement in the S/N ratio of more than 240% using our OC sequences. This motivates the development of a cryoprobe with a larger volume than the current 3-mm cryoprobes.
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Affiliation(s)
- David Joseph
- Max Planck Institute for Multidisciplinary Sciences, Göttingen, Niedersachsen D-37077, Germany
| | - Christian Griesinger
- Max Planck Institute for Multidisciplinary Sciences, Göttingen, Niedersachsen D-37077, Germany
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4
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Das S, Khaneja N. Composite pulse combinations for chirp excitation. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2023; 347:107359. [PMID: 36563420 DOI: 10.1016/j.jmr.2022.107359] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/05/2022] [Revised: 12/13/2022] [Accepted: 12/13/2022] [Indexed: 06/17/2023]
Abstract
Composite pulses are the efficient method for broadband excitation to get control of the limitations of high field NMR, such as resonance offset effects with constraints on rf power that leads to signal intensity distortion. Phase-modulated chirp pulses are used as ordered composite pulse sequences in this paper as CHORUS sequence in a high-field NMR spectrometer (BRUKER 750 MHz) for broadband excitation. The composite pulse sequence applies chirp pulses with the forward and the reverse sweep mechanisms. A single excitation pulse combines adiabatic and non-adiabatic rotation, explained as a three-phase rotation, which leaves the magnetizing vectors to a non-uniform phase dispersion as a function of the offset frequency. One adiabatic refocusing pulse of the double sweep rate after the excitation pulse cannot satisfactorily compensate for the phase dispersion. Hence, composite self-refocussing CHORUS excitation pulse, with forward, reverse, and their combinations are used to remove the non-uniform phase dispersion generated due to offset resonance frequency. Four such combinations of composite pulses are produced with analytical explanation in this paper. MATLAB simulation results and experimental verification on the BRUKER 750 MHz NMR spectrometer of the composite pulses are also presented in this paper.
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Affiliation(s)
- Sreya Das
- Systems and Control Engineering Department, Indian Institute of Technology, Bombay, India.
| | - Navin Khaneja
- Systems and Control Engineering Department, Indian Institute of Technology, Bombay, India
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5
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Slad S, Bermel W, Kümmerle R, Mathieu D, Luy B. Band-selective universal 90° and 180° rotation pulses covering the aliphatic carbon chemical shift range for triple resonance experiments on 1.2 GHz spectrometers. JOURNAL OF BIOMOLECULAR NMR 2022; 76:185-195. [PMID: 36418752 PMCID: PMC9712393 DOI: 10.1007/s10858-022-00404-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/31/2022] [Accepted: 09/02/2022] [Indexed: 06/16/2023]
Abstract
Biomolecular NMR spectroscopy requires large magnetic field strengths for high spectral resolution. Today's highest fields comprise proton Larmor frequencies of 1.2 GHz and even larger field strengths are to be expected in the future. In protein triple resonance experiments, various carbon bandwidths need to be excited by selective pulses including the large aliphatic chemical shift range. When the spectrometer field strength is increased, the length of these pulses has to be decreased by the same factor, resulting in higher rf-amplitudes being necessary in order to cover the required frequency region. Currently available band-selective pulses like Q3/Q5 excite a narrow bandwidth compared to the necessary rf-amplitude. Because the maximum rf-power allowed in probeheads is limited, none of the selective universal rotation pulses reported so far is able to cover the full [Formula: see text]C aliphatic region on 1.2 GHz spectrometers. In this work, we present band-selective 90° and 180° universal rotation pulses (SURBOP90 and SURBOP180) that have a higher ratio of selective bandwidth to maximum rf-amplitude than standard pulses. Simulations show that these pulses perform better than standard pulses, e. g. Q3/Q5, especially when rf-inhomogeneity is taken into account. The theoretical and experimental performance is demonstrated in offset profiles and by implementing the SURBOP pulses in an HNCACB experiment at 1.2 GHz.
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Affiliation(s)
- Stella Slad
- Institute of Organic Chemistry and Institute for Biological Interfaces 4 - Magnetic Resonance, Karlsruhe Institute of Technology (KIT), Fritz-Haber-Weg 6, 76131, Karlsruhe, Germany
| | - Wolfgang Bermel
- Bruker BioSpin GmbH, Rudolf-Plank-Str. 23, 76275, Ettlingen, Germany
| | - Rainer Kümmerle
- Bruker BioSpin AG, Industriestr. 26, 8117, Fällanden, Switzerland
| | - Daniel Mathieu
- Bruker BioSpin GmbH, Rudolf-Plank-Str. 23, 76275, Ettlingen, Germany
| | - Burkhard Luy
- Institute of Organic Chemistry and Institute for Biological Interfaces 4 - Magnetic Resonance, Karlsruhe Institute of Technology (KIT), Fritz-Haber-Weg 6, 76131, Karlsruhe, Germany.
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6
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Haller JD, Bodor A, Luy B. Pure shift amide detection in conventional and TROSY-type experiments of 13C, 15N-labeled proteins. JOURNAL OF BIOMOLECULAR NMR 2022; 76:213-221. [PMID: 36399207 PMCID: PMC9712348 DOI: 10.1007/s10858-022-00406-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/05/2022] [Accepted: 10/24/2022] [Indexed: 06/16/2023]
Abstract
Large coupling networks in uniformly 13C,15N-labeled biomolecules induce broad multiplets that even in flexible proteins are frequently not recognized as such. The reason is that given multiplets typically consist of a large number of individual resonances that result in a single broad line, in which individual components are no longer resolved. We here introduce a real-time pure shift acquisition scheme for the detection of amide protons which is based on 13C-BIRDr,X. As a result the full homo- and heteronuclear coupling network can be suppressed at low power leading to real singlets at substantially improved resolution and uncompromised sensitivity. The method is tested on a small globular and an intrinsically disordered protein (IDP) where the average spectral resolution is increased by a factor of ~ 2 and higher. Equally important, the approach works without saturation of water magnetization for solvent suppression and exchanging amide protons are not affected by saturation transfer.
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Affiliation(s)
- Jens D. Haller
- Institute of Organic Chemistry and Institute for Biological Interfaces 4 – Magnetic Resonance, Karlsruhe Institute of Technology (KIT), Hermann-Von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
| | - Andrea Bodor
- Institute of Chemistry, Analytical and BioNMR Laboratory, ELTE –Eötvös Loránd University, Pázmány Péter Sétány 1/A, 1117 Budapest, Hungary
| | - Burkhard Luy
- Institute of Organic Chemistry and Institute for Biological Interfaces 4 – Magnetic Resonance, Karlsruhe Institute of Technology (KIT), Hermann-Von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
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7
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Graf C, Soellradl M, Aigner CS, Rund A, Stollberger R. Advanced design of MRI inversion pulses for inhomogeneous field conditions by optimal control. NMR IN BIOMEDICINE 2022; 35:e4790. [PMID: 35731240 PMCID: PMC9786750 DOI: 10.1002/nbm.4790] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/07/2022] [Revised: 06/01/2022] [Accepted: 06/19/2022] [Indexed: 06/15/2023]
Abstract
Non-selective inversion pulses find widespread use in MRI applications, where requirements on them are increasingly demanding. With the use of high and ultra-high field strength systems, robustness to Δ B 0 and B 1 + inhomogeneities, while tackling SAR and hardware limitations, has rapidly become important. In this work, we propose a time-optimal control framework for the optimization of Δ B 0 - and B 1 + -robust inversion pulses. Robustness is addressed by means of ensemble formulations, while allowing inclusion of hardware and energy limitations. The framework is flexible and performs excellently for various optimization goals. The optimization results are analyzed extensively in numerical experiments. Furthermore, they are validated, and compared with adiabatic RF pulses, in various phantom and in vivo measurements on a 3 T MRI system.
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Affiliation(s)
- Christina Graf
- Institute of Biomedical ImagingGraz University of TechnologyGrazAustria
| | - Martin Soellradl
- Institute of Biomedical ImagingGraz University of TechnologyGrazAustria
| | | | - Armin Rund
- Institute for Mathematics and Scientific ComputingUniversity of GrazGrazAustria
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8
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Haller J, Goodwin D, Luy B. SORDOR pulses: expansion of the Böhlen-Bodenhausen scheme for low-power broadband magnetic resonance. MAGNETIC RESONANCE (GOTTINGEN, GERMANY) 2022; 3:53-63. [PMID: 37905174 PMCID: PMC10539771 DOI: 10.5194/mr-3-53-2022] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/12/2022] [Accepted: 03/28/2022] [Indexed: 11/02/2023]
Abstract
A novel type of efficient broadband pulse, called second-order phase dispersion by optimised rotation (SORDOR), has recently been introduced. In contrast to adiabatic excitation, SORDOR-90 pulses provide effective transverse 90∘ rotations throughout their bandwidth, with a quadratic offset dependence of the phase in the x , y plane. Together with phase-matched SORDOR-180 pulses, this enables the Böhlen-Bodenhausen broadband refocusing approach for linearly frequency-swept pulses to be extended to any type of 90∘ /180∘ pulse-delay sequence. Example pulse shapes are characterised in theory and experiment, and an example application is given with a 19 F -PROJECT experiment for measuring relaxation times with reduced distortions due to J -coupling evolution.
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Affiliation(s)
- Jens D. Haller
- Institute for Biological Interfaces 4 – Magnetic Resonance, Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany
| | - David L. Goodwin
- Institute for Biological Interfaces 4 – Magnetic Resonance, Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany
| | - Burkhard Luy
- Institute for Biological Interfaces 4 – Magnetic Resonance, Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany
- Institute of Organic Chemistry, Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany
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9
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Ehni S, Koos MRM, Reinsperger T, Haller JD, Goodwin DL, Luy B. Concurrent J-evolving refocusing pulses. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2022; 336:107152. [PMID: 35189510 DOI: 10.1016/j.jmr.2022.107152] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/23/2021] [Revised: 01/06/2022] [Accepted: 01/25/2022] [Indexed: 06/14/2023]
Abstract
Conventional refocusing pulses are optimised for a single spin without considering any type of coupling. However, despite the fact that most couplings will result in undesired distortions, refocusing in delay-pulse-delay-type sequences with desired heteronuclear coherence transfer might be enhanced considerably by including coupling evolution into pulse design. We provide a proof of principle study for a Hydrogen-Carbon refocusing pulse sandwich with inherent J-evolution following the previously reported ICEBERG-principle with improved performance in terms of refocusing performance and/or overall effective coherence transfer time. Pulses are optimised using optimal control theory with a newly derived quality factor and z-controls as an efficient tool to speed up calculations. Pulses are characterised in theory and experiment and compared to conventional concurrent refocusing pulses, clearly showing an improvement for the J-evolving pulse sandwich. As a side-product, also efficient J-compensated resfocusing pulse sandwiches - termed BUBU pulses following the nomenclature of previous J-compensated BUBI and BEBEtr pulse sandwiches - have been optimised.
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Affiliation(s)
- Sebastian Ehni
- Institute for Biological Interfaces 4 - Magnetic Resonance, Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany; Institute of Organic Chemistry, Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany; Bruker Biospin GmbH, Fällanden 8117, Switzerland
| | - Martin R M Koos
- Institute for Biological Interfaces 4 - Magnetic Resonance, Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany; Pfizer Inc., Groton, CT 06340, USA; Department of Chemistry, Carnegie Mellon University, Pittsburgh, USA
| | - Tony Reinsperger
- Institute for Biological Interfaces 4 - Magnetic Resonance, Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany; Institute of Organic Chemistry, Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany; Bruker Biospin GmbH, Ettlingen 76275, Germany
| | - Jens D Haller
- Institute for Biological Interfaces 4 - Magnetic Resonance, Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany; Institute of Organic Chemistry, Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany
| | - David L Goodwin
- Institute for Biological Interfaces 4 - Magnetic Resonance, Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany; Chemistry Research Laboratory, University of Oxford, Mansfield Road, Oxford OX1 3TA, UK.
| | - Burkhard Luy
- Institute for Biological Interfaces 4 - Magnetic Resonance, Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany; Institute of Organic Chemistry, Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany.
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10
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Martikyan V, Beluffi C, Glaser SJ, Delsuc MA, Sugny D. Application of Optimal Control Theory to Fourier Transform Ion Cyclotron Resonance. Molecules 2021; 26:molecules26102860. [PMID: 34065881 PMCID: PMC8151339 DOI: 10.3390/molecules26102860] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2021] [Revised: 05/03/2021] [Accepted: 05/05/2021] [Indexed: 11/30/2022] Open
Abstract
We study the application of Optimal Control Theory to Ion Cyclotron Resonance. We test the validity and the efficiency of this approach for the robust excitation of an ensemble of ions with a wide range of cyclotron frequencies. Optimal analytical solutions are derived in the case without any pulse constraint. A gradient-based numerical optimization algorithm is proposed to take into account limitation in the control intensity. The efficiency of optimal pulses is investigated as a function of control time, maximum amplitude and range of excited frequencies. A comparison with adiabatic and SWIFT pulses is done. On the basis of recent results in Nuclear Magnetic Resonance, this study highlights the potential usefulness of optimal control in Ion Cyclotron Resonance.
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Affiliation(s)
- Vardan Martikyan
- Laboratoire Interdisciplinaire Carnot de Bourgogne (ICB), UMR 6303 CNRS-Université Bourgogne-Franche Comté, 9 Av. A. Savary, BP 47 870, F-21078 Dijon, France;
| | - Camille Beluffi
- CASC4DE S.A.S, Pole API Batiment 1, 300 Boulevard Sébastien Brant, 67400 Illkirch, France; (C.B.); (M.-A.D.)
| | - Steffen J. Glaser
- Department of Chemistry, Technische Universität München, Lichtenbergstrasse 4, D-85747 Garching, Germany;
- Munich Center for Quantum Science and Technology (MCQST), Schellingstrasse 4, 80799 München, Germany
| | - Marc-André Delsuc
- CASC4DE S.A.S, Pole API Batiment 1, 300 Boulevard Sébastien Brant, 67400 Illkirch, France; (C.B.); (M.-A.D.)
- IGBMC, 1 rue laurent Fries, BP 10142, 67404 Illkirch, France
| | - Dominique Sugny
- Laboratoire Interdisciplinaire Carnot de Bourgogne (ICB), UMR 6303 CNRS-Université Bourgogne-Franche Comté, 9 Av. A. Savary, BP 47 870, F-21078 Dijon, France;
- Correspondence:
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11
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Verstraete JB, Myers WK, Foroozandeh M. Chirped ordered pulses for ultra-broadband ESR spectroscopy. J Chem Phys 2021; 154:094201. [PMID: 33685137 DOI: 10.1063/5.0038511] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Recently, applications of swept-frequency pulses proved to be a useful approach to circumvent the problem of limited excitation bandwidth in pulsed ESR posed by conventional pulses. Here, we present a chirped excitation sequence, CHirped ORdered pulses for Ultra-broadband Spectroscopy (CHORUS), for ultra-broadband ESR spectroscopy. It will be demonstrated that the application of this sequence can address the problems of excitation non-uniformity and sensitivity to instrumental instabilities to a greater extent compared to the current state of the art. This sequence is highly promising for finding applications beyond single excitation in many ESR experiments. Theoretical and experimental results for the proposed method are presented along with calibration strategies for experimental implementation.
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Affiliation(s)
- Jean-Baptiste Verstraete
- Chemistry Research Laboratory, University of Oxford, Mansfield Road, Oxford OX1 3TA, United Kingdom
| | - William K Myers
- Centre for Advanced ESR, Inorganic Chemistry Laboratory, University of Oxford, South Parks Road, Oxford OX1 3QR, United Kingdom
| | - Mohammadali Foroozandeh
- Chemistry Research Laboratory, University of Oxford, Mansfield Road, Oxford OX1 3TA, United Kingdom
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12
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Xu F, Li W, Liu D, Zhu D, Schär M, Myers K, Qin Q. A novel spectrally selective fat saturation pulse design with robustness to B 0 and B 1 inhomogeneities: A demonstration on 3D T 1-weighted breast MRI at 3 T. Magn Reson Imaging 2020; 75:156-161. [PMID: 33130057 DOI: 10.1016/j.mri.2020.10.015] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2020] [Revised: 10/25/2020] [Accepted: 10/26/2020] [Indexed: 12/01/2022]
Abstract
PURPOSE Spectrally selective fat saturation (FatSat) sequence is commonly used to suppress signal from adipose tissue. Conventional SINC-shaped pulses are sensitive to B0 off-resonance and B1+ offset. Uniform fat saturation with large spatial coverage is especially challenging for the body and breast MRI. The aim of this study is to develop spectrally selective FatSat pulses that offer more immunity to B0/B1+ field inhomogeneities than SINC pulses and evaluate them in bilateral breast imaging at 3 T. MATERIALS AND METHODS Optimized composite pulses (OCP) were designed based on the optimal control theory with robustness to a targeted B0/ B1+ conditions. OCP pulses also allows flexible flip angles to meet different requirements. Comparisons with the vendor-provided SINC pulses were conducted by numerical simulation and in vivo scans using a 3D T1-weighted (T1w) gradient-echo (GRE) sequence with coverage of the whole-breast. RESULTS Simulation revealed that OCP pulses yielded almost half of the transition band and much less sensitivity to B1+ inhomogeneity compared to SINC pulses with B0 off-resonance within ±200 Hz and B1+ scale error within ±0.3 (P < 0.001). Across five normal subjects, OCP FatSat pulses produced 25-41% lower residual fat signals (P < 0.05) with 27-36% less spatial variation (P < 0.05) than SINC. CONCLUSION In contrast to conventional SINC-shaped pulses, the newly designed OCP FatSat pulses mitigated challenges of wide range of B0/ B1+ field inhomogeneities and achieved more uniform fat suppression in bilateral breast T1w imaging at 3 T.
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Affiliation(s)
- Feng Xu
- The Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD, USA; F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, USA.
| | - Wenbo Li
- The Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD, USA; F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, USA
| | - Dapeng Liu
- The Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD, USA; F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, USA
| | - Dan Zhu
- Biomedical Engineering, Johns Hopkins School of Medicine, Baltimore, MD, USA
| | - Michael Schär
- The Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Kelly Myers
- The Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Qin Qin
- The Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD, USA; F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, USA
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13
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Bodor A, Haller JD, Bouguechtouli C, Theillet FX, Nyitray L, Luy B. Power of Pure Shift HαCα Correlations: A Way to Characterize Biomolecules under Physiological Conditions. Anal Chem 2020; 92:12423-12428. [PMID: 32786451 DOI: 10.1021/acs.analchem.0c02182] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Intrinsically disordered proteins (IDPs) constitute an important class of biomolecules with high flexibility. Atomic-resolution studies for these molecules are essentially limited to NMR spectroscopy, which should be performed under physiological pH and temperature to populate relevant conformational ensembles. In this context, however, fundamental problems arise with established triple resonance NMR experiments: high solvent accessibility of IDPs promotes water exchange, which disfavors classical amide 1H-detection, while 13C-detection suffers from significantly reduced sensitivity. A favorable alternative, the conventional detection of nonexchangeable 1Hα, so far resulted in broad signals with insufficient resolution and sensitivity. To overcome this, we introduce here a selective Hα,Cα-correlating pure shift detection scheme, the selective Hα,Cα-HSQC (SHACA-HSQC), using extensive hetero- and homonuclear decoupling applicable to aqueous samples (≥90% H2O) and tested on small molecules and proteins. SHACA-HSQC spectra acquired on IDPs provide uncompromised resolution and sensitivity (up to fivefold increased S/N compared to the standard 1H,13C-HSQC), as shown for resonance distinction and unambiguous assignment on the disordered transactivation domain of the tumor suppressor p53, α-synuclein, and folded ubiquitin. The detection scheme can be implemented in any 1Hα-detected triple resonance experiment and may also form the basis for the detection of isotope-labeled markers in biological studies or compound libraries.
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Affiliation(s)
- Andrea Bodor
- Institute of Chemistry, Eötvös Loránd University, Pázmány Péter sétány 1/a, Budapest 1117, Hungary
| | - Jens D Haller
- Institut für Organische Chemie and Institut für Biologische Grenzflächen 4-Magnetische Resonanz, Karlsruher Institut für Technologie (KIT), Fritz-Haber-Weg 6, Karlsruhe 76133, Germany
| | - Chafiaa Bouguechtouli
- Institute of Integrative Biology of the Cell, UMR9198, CNRS/CEA/ University of Paris Saclay, Gif-Sur-Yvette 911991, France
| | - Francois-Xavier Theillet
- Institute of Integrative Biology of the Cell, UMR9198, CNRS/CEA/ University of Paris Saclay, Gif-Sur-Yvette 911991, France
| | - László Nyitray
- Department of Biochemistry, Eötvös Loránd University, Pázmány Péter sétány 1/c, Budapest 1117, Hungary
| | - Burkhard Luy
- Institut für Organische Chemie and Institut für Biologische Grenzflächen 4-Magnetische Resonanz, Karlsruher Institut für Technologie (KIT), Fritz-Haber-Weg 6, Karlsruhe 76133, Germany
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14
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Altenhof AR, Lindquist AW, Foster LDD, Holmes ST, Schurko RW. On the use of frequency-swept pulses and pulses designed with optimal control theory for the acquisition of ultra-wideline NMR spectra. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2019; 309:106612. [PMID: 31622849 DOI: 10.1016/j.jmr.2019.106612] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2019] [Revised: 09/19/2019] [Accepted: 09/20/2019] [Indexed: 06/10/2023]
Abstract
Frequency-swept (FS) pulses, such as wideband uniform-rate smooth-truncation (WURST) pulses, have found much success for the acquisition of ultra-wideline (UW) solid-state NMR spectra. In this preliminary study, new pulses and pulse sequences are explored in simulation and experimentally for several nuclei exhibiting UWNMR powder patterns under static conditions, including 119Sn (I = 1/2), 195Pt (I = 1/2), 2H (I = 1), and 71Ga (I = 3/2). First, hyperbolic secant (HS) and tanh/tan (THT) pulses are tested and implemented as excitation and refocusing pulses in spin-echo and Carr-Purcell/Meiboom Gill (CPMG)-type sequences, and shown to have comparable performances to analogous WURST pulses. Second, optimal control theory (OCT) is utilized for the design of new Optimal Control Theory Optimized Broadband Excitation and Refocusing (OCTOBER) pulses, using carefully parameterized WURST, THT, and HS pulses as starting points. Some of the new OCTOBER pulses used in spin-echo sequences are capable of efficient broadband excitation and refocusing, in some cases resulting in spectra with increased signal enhancements over those obtained in experiments using conventional FS pulses. Finally, careful consideration of the spin dynamics of several systems, by monitoring of the time evolution of the density matrix via the Liouville-von Neumann equation and analysis of the time-resolved Fourier transforms of the pulses, lends insight into the underlying mechanisms of the FS and OCTOBER pulses. This is crucial for understanding their performance in terms of generating uniformly excited patterns of high signal intensity, and for identifying trends that may offer pathways to generalized parameterization and/or new pulse shapes.
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Affiliation(s)
- Adam R Altenhof
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, FL 32308, United States
| | - Austin W Lindquist
- Department of Chemistry and Biochemistry, University of Windsor, Windsor, ON N9B 3P4, Canada
| | - Lucas D D Foster
- Department of Chemistry and Biochemistry, University of Windsor, Windsor, ON N9B 3P4, Canada
| | - Sean T Holmes
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, FL 32308, United States
| | - Robert W Schurko
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, FL 32308, United States.
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15
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Haller JD, Bodor A, Luy B. Real-time pure shift measurements for uniformly isotope-labeled molecules using X-selective BIRD homonuclear decoupling. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2019; 302:64-71. [PMID: 30965191 DOI: 10.1016/j.jmr.2019.03.011] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2019] [Revised: 03/28/2019] [Accepted: 03/29/2019] [Indexed: 06/09/2023]
Abstract
We introduce a novel selective inversion element for chunked homonuclear decoupling that combines isotope selection via BIRD-filtering with band-selective inversion on the X-heteronucleus and allows efficient real-time decoupling of homonuclear and heteronuclear couplings. It is especially suitable for uniformly isotope-labeled compounds. We discuss in detail the inversion element based on band-selective refocusing on the X-nuclei (BASEREX), highlighting in particular the role of appropriate band-selective shaped refocusing pulses and the application of broadband X-pulses for an effective BIRDd element during homodecoupling. The approach is experimentally verified and studied in detail using uniformly 13C-labeled glucose and a uniformly 15N,13C-labeled amino acid mixture.
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Affiliation(s)
- Jens D Haller
- Institut für Organische Chemie and Institut für Biologische Grenzflächen 4 - Magnetische Resonanz, Karlsruher Institut für Technologie (KIT), Fritz-Haber-Weg 6, 76133 Karlsruhe, Germany
| | - Andrea Bodor
- Eötvös Loránd University, Institute of Chemistry, Laboratory of Structural Chemistry and Biology, Pázmány Péter sétány 1/a, Budapest 1117, Hungary
| | - Burkhard Luy
- Institut für Organische Chemie and Institut für Biologische Grenzflächen 4 - Magnetische Resonanz, Karlsruher Institut für Technologie (KIT), Fritz-Haber-Weg 6, 76133 Karlsruhe, Germany.
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16
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Foroozandeh M, Nilsson M, Morris GA. Improved ultra-broadband chirp excitation. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2019; 302:28-33. [PMID: 30939336 DOI: 10.1016/j.jmr.2019.03.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2019] [Revised: 03/20/2019] [Accepted: 03/21/2019] [Indexed: 06/09/2023]
Abstract
The design and application of ultra-broadband excitation pulses have been among the most interesting and timely areas in NMR and EPR methodology in recent years, due especially to advances in hardware design in EPR, the advent and popularity of high- and ultrahigh-field NMR, and the application of numerical methods like optimal control theory to the design and optimization of radiofrequency pulses and pulse sequences. In this communication, we present a short, robust, and flexible version of the CHORUS family of constant-phase, very broadband excitation sequences. We demonstrate that more than 0.5 MHz excitation with uniform amplitudes and phases can be achieved with this excitation sequence.
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Affiliation(s)
| | - Mathias Nilsson
- School of Chemistry, University of Manchester, Oxford Road, Manchester M13 9PL, UK
| | - Gareth A Morris
- School of Chemistry, University of Manchester, Oxford Road, Manchester M13 9PL, UK
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17
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Becker J, Koos MRM, Schulze-Sünninghausen D, Luy B. ASAP-HSQC-TOCSY for fast spin system identification and extraction of long-range couplings. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2019; 300:76-83. [PMID: 30711785 DOI: 10.1016/j.jmr.2018.12.021] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/17/2018] [Revised: 12/19/2018] [Accepted: 12/20/2018] [Indexed: 06/09/2023]
Abstract
Based on Ernst-angle-type excitation and Acceleration by Sharing Adjacent Polarization (ASAP), a fast HSQC-TOCSY experiment is introduced. In the approach, the DIPSI-2 isotropic mixing period of the ASAP-HSQC is simply shifted, which provides a TOCSY period without additional application of rf-energy. The ASAP-HSQC-TOCSY allows the acquisition of a conventional 2D in about 30 s. Alternatively, it allows the acquisition of highly carbon-resolved spectra (several Hz digital resolution) on the order of minutes. An ASAP-HSQC-TOCSY-IPAP variant, finally, allows the sign-sensitive extraction of heteronuclear long-range coupling constants from a pair of highly resolved spectra in less than an hour. Pulse sequences, several example spectra, and a discussion of results are given.
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Affiliation(s)
- Johanna Becker
- Institut für Organische Chemie and Institut für Biologische Grenzflächen, Karlsruher Institut für Technologie (KIT), Fritz-Haber-Weg 6, 76131 Karlsruhe, Germany
| | - Martin R M Koos
- Institut für Organische Chemie and Institut für Biologische Grenzflächen, Karlsruher Institut für Technologie (KIT), Fritz-Haber-Weg 6, 76131 Karlsruhe, Germany
| | - David Schulze-Sünninghausen
- Institut für Organische Chemie and Institut für Biologische Grenzflächen, Karlsruher Institut für Technologie (KIT), Fritz-Haber-Weg 6, 76131 Karlsruhe, Germany
| | - Burkhard Luy
- Institut für Organische Chemie and Institut für Biologische Grenzflächen, Karlsruher Institut für Technologie (KIT), Fritz-Haber-Weg 6, 76131 Karlsruhe, Germany.
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18
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Rodin BA, Kiryutin AS, Yurkovskaya AV, Ivanov KL, Yamamoto S, Sato K, Takui T. Using optimal control methods with constraints to generate singlet states in NMR. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2018; 291:14-22. [PMID: 29626735 DOI: 10.1016/j.jmr.2018.03.005] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/20/2017] [Revised: 02/06/2018] [Accepted: 03/09/2018] [Indexed: 06/08/2023]
Abstract
A method is proposed for optimizing the performance of the APSOC (Adiabatic-Passage Spin Order Conversion) technique, which can be exploited in NMR experiments with singlet spin states. In this technique magnetization-to-singlet conversion (and singlet-to-magnetization conversion) is performed by using adiabatically ramped RF-fields. Optimization utilizes the GRAPE (Gradient Ascent Pulse Engineering) approach, in which for a fixed search area we assume monotonicity to the envelope of the RF-field. Such an approach allows one to achieve much better performance for APSOC; consequently, the efficiency of magnetization-to-singlet conversion is greatly improved as compared to simple model RF-ramps, e.g., linear ramps. We also demonstrate that the optimization method is reasonably robust to possible inaccuracies in determining NMR parameters of the spin system under study and also in setting the RF-field parameters. The present approach can be exploited in other NMR and EPR applications using adiabatic switching of spin Hamiltonians.
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Affiliation(s)
- Bogdan A Rodin
- International Tomography Center SB RAS, Novosibirsk 630090, Russia; Novosibirsk State University, Novosibirsk 630090, Russia
| | - Alexey S Kiryutin
- International Tomography Center SB RAS, Novosibirsk 630090, Russia; Novosibirsk State University, Novosibirsk 630090, Russia
| | - Alexandra V Yurkovskaya
- International Tomography Center SB RAS, Novosibirsk 630090, Russia; Novosibirsk State University, Novosibirsk 630090, Russia
| | - Konstantin L Ivanov
- International Tomography Center SB RAS, Novosibirsk 630090, Russia; Novosibirsk State University, Novosibirsk 630090, Russia.
| | - Satoru Yamamoto
- Graduate School of Science, Osaka City University, Osaka, Sumiyoshi, Osaka 558-8585, Japan
| | - Kazunobu Sato
- Graduate School of Science, Osaka City University, Osaka, Sumiyoshi, Osaka 558-8585, Japan
| | - Takeji Takui
- Graduate School of Science, Osaka City University, Osaka, Sumiyoshi, Osaka 558-8585, Japan
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19
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Gyöngyösi T, Timári I, Haller J, Koos MRM, Luy B, Kövér KE. Boosting the NMR Assignment of Carbohydrates with Clean In-Phase Correlation Experiments. Chempluschem 2018; 83:53-60. [PMID: 31957316 DOI: 10.1002/cplu.201700452] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2017] [Revised: 12/18/2017] [Indexed: 12/12/2022]
Abstract
Novel CLIP-COSY based homo- and heteronuclear correlation experiments are reported for the rapid, semi-automated NMR assignment of small to medium-sized molecules. The homonuclear CLIP-COSY and corresponding relayed experiments employ the perfect-echo based mixing sequence for in-phase coherence transfer between directly and/or indirectly coupled proton spins. The combined analysis of the resulting CLIP-COSY and relayed spectra made it possible to easily track down, layer by layer, the proton-proton connectivity network. In larger molecules the narrow chemical shift range of protons may, however, compromise the efficacy of the homonuclear correlation based assignment strategy. To overcome this limitation, an HSQC variant of the CLIP-COSY experiment has now been devised. Combined treatment of HSQC-CLIP-COSY (relayed) and standard HSQC spectra facilitates simultaneous and semi-automatic assignment of 1 H and 13 C resonances of medium-sized molecules, such as pentasaccharides. The recently introduced PSYCHE broadband homonuclear decoupling scheme has been also implemented into the devised homo- and heteronuclear CLIP-COSY based experiments, resulting in fully decoupled high-resolution pure-shift correlation spectra.
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Affiliation(s)
- Tamás Gyöngyösi
- Department of Inorganic and Analytical Chemistry, University of Debrecen, Egyetem tér 1, Debrecen, 4032, Hungary
| | - István Timári
- Department of Inorganic and Analytical Chemistry, University of Debrecen, Egyetem tér 1, Debrecen, 4032, Hungary.,Department of Chemistry and Biochemistry, The Ohio State University, 100 West 18th Avenue, Columbus, OH, 43210, USA
| | - Jens Haller
- Institute of Organic Chemistry, and Institute for Biological Interfaces 4-Magnetic Resonance, Karlsruhe Institute of Technology (KIT), Fritz-Haber-Weg 6, 76131, Karlsruhe, Germany
| | - Martin R M Koos
- Institute of Organic Chemistry, and Institute for Biological Interfaces 4-Magnetic Resonance, Karlsruhe Institute of Technology (KIT), Fritz-Haber-Weg 6, 76131, Karlsruhe, Germany
| | - Burkhard Luy
- Institute of Organic Chemistry, and Institute for Biological Interfaces 4-Magnetic Resonance, Karlsruhe Institute of Technology (KIT), Fritz-Haber-Weg 6, 76131, Karlsruhe, Germany
| | - Katalin E Kövér
- Department of Inorganic and Analytical Chemistry, University of Debrecen, Egyetem tér 1, Debrecen, 4032, Hungary
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20
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Kallies W, Glaser SJ. Cooperative broadband spin echoes through optimal control. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2018; 286:115-137. [PMID: 29241044 DOI: 10.1016/j.jmr.2017.10.011] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/29/2017] [Revised: 10/25/2017] [Accepted: 10/29/2017] [Indexed: 06/07/2023]
Abstract
The Hahn echo sequence is one of the most common building blocks in magnetic resonance, consisting of an excitation pulse and a refocusing pulse. Conventional approaches to improve the performance of echo experiments focused on the optimization of individual pulses, compensating their own imperfections. Here we present an approach to concurrently design both pulses such that they also compensate each others imperfections. The fact that for such cooperative pulses the individual pulses do not need to be perfect provides additional degrees of freedom, resulting in improved overall Hahn echo performance. Single-scan cooperative pulses are compared to conventional approaches by simulations as well as experiments.
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Affiliation(s)
- Wolfgang Kallies
- Department of Chemistry, Technical University of Munich, Lichtenbergstr. 4, 85748 Garching, Germany
| | - Steffen J Glaser
- Department of Chemistry, Technical University of Munich, Lichtenbergstr. 4, 85748 Garching, Germany.
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21
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Koos MRM, Feyrer H, Luy B. Broadband RF-amplitude-dependent flip angle pulses with linear phase slope. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2017; 55:797-803. [PMID: 28321918 DOI: 10.1002/mrc.4593] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2016] [Revised: 03/08/2017] [Accepted: 03/11/2017] [Indexed: 06/06/2023]
Abstract
Pulse sequences in NMR spectroscopy sometimes require the application of pulses with effective flip angles different from 90° and 180°. Previously (Magn. Reson. Chem. 2015, 53, 886-893), offset-compensated broadband excitation pulses with RF-amplitude-dependent effective flip angles (RADFA) were introduced that are applicable in such cases. However, especially RF-amplitude-restricted RADFA pulses turned out to perform not as good as desired in terms of achievable bandwidths. Here, a class of RF-amplitude-restricted RADFA pulses with linear phase slope is introduced that allows excitation over much larger bandwidths with better performance. In this theoretical work, the basic principle of the pulse class is explained, their physical limits explored, and their properties, also compared with other pulse classes, discussed in detail. Copyright © 2017 John Wiley & Sons, Ltd.
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Affiliation(s)
- Martin R M Koos
- Institut für Biologische Grenzflächen 4 - Magnetische Resonanz, Karlsruher Institut für Technologie (KIT), Postfach 3640, 76021, Karlsruhe, Germany
| | - Hannes Feyrer
- Institut für Organische Chemie, Karlsruher Institut für Technologie (KIT), Fritz-Haber-Weg 6, 76131, Karlsruhe, Germany
- Department of Medical Biochemistry and Biophysics (MBB), Karolinska Institutet, Scheeles Väg 2, 171 77, Stockholm, Sweden
| | - Burkhard Luy
- Institut für Biologische Grenzflächen 4 - Magnetische Resonanz, Karlsruher Institut für Technologie (KIT), Postfach 3640, 76021, Karlsruhe, Germany
- Institut für Organische Chemie, Karlsruher Institut für Technologie (KIT), Fritz-Haber-Weg 6, 76131, Karlsruhe, Germany
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22
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Nguyen TT, Glaser SJ. An optimal control approach to design entire relaxation dispersion experiments. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2017; 282:142-153. [PMID: 28822305 DOI: 10.1016/j.jmr.2017.07.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/20/2017] [Revised: 07/21/2017] [Accepted: 07/29/2017] [Indexed: 06/07/2023]
Abstract
A general approach is introduced to optimize experiments for the analysis of spin systems in the presence of chemical exchange. Rather than optimizing individual pulse sequence elements, such as refocusing pulses, entire relaxation dispersion sequences are optimized in the form of a single shaped pulse. This is achieved by defining a performance index that is only based on the remaining signal after the relaxation dispersion sequence for a range of exchange, relaxation, offset, and rf inhomogeneity parameters. The approach is demonstrated by optimizing energy-limited broadband relaxation dispersion sequences that closely approach the overall effect of ideal CPMG sequences. As illustrated both theoretically and experimentally, significant improvements are found compared to standard amplitude or energy-limited CPMG sequences.
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Affiliation(s)
- Thoa T Nguyen
- Technical University of Munich, Department of Chemistry, Lichtenbergstr. 4, 85747 Garching, Germany
| | - Steffen J Glaser
- Technical University of Munich, Department of Chemistry, Lichtenbergstr. 4, 85747 Garching, Germany.
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23
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Khaneja N. Chirp excitation. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2017; 282:32-36. [PMID: 28732341 DOI: 10.1016/j.jmr.2017.07.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/15/2017] [Revised: 07/01/2017] [Accepted: 07/11/2017] [Indexed: 06/07/2023]
Abstract
The paper describes the design of broadband chirp excitation pulses. We first develop a three stage model for understanding chirp excitation in NMR. We then show how a chirp π pulse can be used to refocus the phase of the chirp excitation pulse. The resulting magnetization still has some phase dispersion in it. We show how a combination of two chirp π pulses instead of one can be used to eliminate this dispersion, leaving behind a small residual phase dispersion. The excitation pulse sequence presented here allows exciting arbitrary large bandwidths without increasing the peak rf-amplitude. Experimental excitation profiles for the residual HDO signal in a sample of 99.5% D2O are displayed as a function of resonance offset. Although methods presented in this paper have appeared elsewhere, we present complete analytical treatment that elucidates the working of these methods.
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Affiliation(s)
- Navin Khaneja
- Department of Electrical Engineering, IIT Bombay, Powai 400076, India.
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24
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Schulze-Sünninghausen D, Becker J, Koos MRM, Luy B. Improvements, extensions, and practical aspects of rapid ASAP-HSQC and ALSOFAST-HSQC pulse sequences for studying small molecules at natural abundance. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2017; 281:151-161. [PMID: 28603039 DOI: 10.1016/j.jmr.2017.05.012] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2017] [Revised: 05/17/2017] [Accepted: 05/22/2017] [Indexed: 06/07/2023]
Abstract
Previously we introduced two novel NMR experiments for small molecules, the so-called ASAP-HSQC and ALSOFAST-HSQC (Schulze-Sünninghausen et al., 2014), which allow the detection of heteronuclear one-bond correlations in less than 30s at natural abundance. We propose an improved symmetrized pulse scheme of the basic experiment to minimize artifact intensities and the combination with non-uniform sampling to enable the acquisition of conventional HSQC spectra in as short as a couple of seconds and extremely 13C-resolved spectra in less than ten minutes. Based on steady state investigations, a first estimate to relative achievable signal intensities with respect to conventional, ASAP-, and ALSOFAST-HSQC experiments is given. In addition, we describe several extensions to the basic pulse schemes, like a multiplicity-edited version, a revised symmetrized CLIP-ASAP-HSQC, an ASAP-/ALSOFAST-HSQC sequence with broadband BIRD-based 1H,1H decoupling, and a symmetrized sequence optimized for water suppression. Finally, RF-power considerations with respect to the high duty cycle of the experiments are given.
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Affiliation(s)
- David Schulze-Sünninghausen
- Institute of Organic Chemistry and Institute for Biological Interfaces 4 - Magnetic Resonance, Karlsruhe Institute of Technology (KIT), Fritz-Haber-Weg 6, 76131 Karlsruhe, Germany; Bruker BioSpin GmbH, Rudolf-Plank-Str. 23, 76275 Ettlingen, Germany
| | - Johanna Becker
- Institute of Organic Chemistry and Institute for Biological Interfaces 4 - Magnetic Resonance, Karlsruhe Institute of Technology (KIT), Fritz-Haber-Weg 6, 76131 Karlsruhe, Germany
| | - Martin R M Koos
- Institute of Organic Chemistry and Institute for Biological Interfaces 4 - Magnetic Resonance, Karlsruhe Institute of Technology (KIT), Fritz-Haber-Weg 6, 76131 Karlsruhe, Germany
| | - Burkhard Luy
- Institute of Organic Chemistry and Institute for Biological Interfaces 4 - Magnetic Resonance, Karlsruhe Institute of Technology (KIT), Fritz-Haber-Weg 6, 76131 Karlsruhe, Germany.
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25
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Reller M, Wesp S, Koos MRM, Reggelin M, Luy B. Biphasic Liquid Crystal and the Simultaneous Measurement of Isotropic and Anisotropic Parameters by Spatially Resolved NMR Spectroscopy. Chemistry 2017. [DOI: 10.1002/chem.201702126] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Malin Reller
- Institut für Organische Chemie and Institut für Biologische Grenzflächen 4 - Magnetische Resonanz; Karlsruher Institut für Technologie (KIT); Fritz-Haber-Weg 6 76131 Karlsruhe Germany
| | - Svenja Wesp
- Organische Chemie; Technische Universität Darmstadt; Alarich-Weiss Str. 4 64287 Darmstadt Germany
| | - Martin R. M. Koos
- Institut für Organische Chemie and Institut für Biologische Grenzflächen 4 - Magnetische Resonanz; Karlsruher Institut für Technologie (KIT); Fritz-Haber-Weg 6 76131 Karlsruhe Germany
| | - Michael Reggelin
- Organische Chemie; Technische Universität Darmstadt; Alarich-Weiss Str. 4 64287 Darmstadt Germany
| | - Burkhard Luy
- Institut für Organische Chemie and Institut für Biologische Grenzflächen 4 - Magnetische Resonanz; Karlsruher Institut für Technologie (KIT); Fritz-Haber-Weg 6 76131 Karlsruhe Germany
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26
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Spindler PE, Schöps P, Kallies W, Glaser SJ, Prisner TF. Perspectives of shaped pulses for EPR spectroscopy. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2017; 280:30-45. [PMID: 28579101 DOI: 10.1016/j.jmr.2017.02.023] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2016] [Revised: 02/27/2017] [Accepted: 02/28/2017] [Indexed: 06/07/2023]
Abstract
This article describes current uses of shaped pulses, generated by an arbitrary waveform generator, in the field of EPR spectroscopy. We show applications of sech/tanh and WURST pulses to dipolar spectroscopy, including new pulse schemes and procedures, and discuss the more general concept of optimum-control-based pulses for applications in EPR spectroscopy. The article also describes a procedure to correct for experimental imperfections, mostly introduced by the microwave resonator, and discusses further potential applications and limitations of such pulses.
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Affiliation(s)
- Philipp E Spindler
- Institute of Physical and Theoretical Chemistry and Center of Biomolecular Magnetic Resonance, Goethe University Frankfurt, Germany
| | - Philipp Schöps
- Institute of Physical and Theoretical Chemistry and Center of Biomolecular Magnetic Resonance, Goethe University Frankfurt, Germany
| | - Wolfgang Kallies
- Department of Chemistry, Technical University of Munich, Germany
| | - Steffen J Glaser
- Department of Chemistry, Technical University of Munich, Germany
| | - Thomas F Prisner
- Institute of Physical and Theoretical Chemistry and Center of Biomolecular Magnetic Resonance, Goethe University Frankfurt, Germany.
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27
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Koos MRM, Kummerlöwe G, Kaltschnee L, Thiele CM, Luy B. CLIP-COSY: A Clean In-Phase Experiment for the Rapid Acquisition of COSY-type Correlations. Angew Chem Int Ed Engl 2016; 55:7655-9. [DOI: 10.1002/anie.201510938] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2015] [Revised: 02/05/2016] [Indexed: 11/09/2022]
Affiliation(s)
- Martin R. M. Koos
- Institut für Organische Chemie and Institut für Biologische, Grenzflächen 4-Magnetische Resonanz; Karlsruher Institut für Technologie (KIT); Fritz-Haber-Weg 6 76131 Karlsruhe Germany
| | - Grit Kummerlöwe
- Institut für Organische Chemie; Technische Universität München; Lichtenbergstrasse 4 85747 Garching Germany
| | - Lukas Kaltschnee
- Clemens-Schöpf-Institut für Organische Chemie und Biochemie; Technische Universität Darmstadt; Alarich-Weiss-Strasse 16 64287 Darmstadt Germany
| | - Christina M. Thiele
- Clemens-Schöpf-Institut für Organische Chemie und Biochemie; Technische Universität Darmstadt; Alarich-Weiss-Strasse 16 64287 Darmstadt Germany
| | - Burkhard Luy
- Institut für Organische Chemie and Institut für Biologische, Grenzflächen 4-Magnetische Resonanz; Karlsruher Institut für Technologie (KIT); Fritz-Haber-Weg 6 76131 Karlsruhe Germany
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28
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Koos MRM, Kummerlöwe G, Kaltschnee L, Thiele CM, Luy B. CLIP-COSY: Reine Inphase-Signale und schnelle Akquisition COSY-artiger Korrelationen. Angew Chem Int Ed Engl 2016. [DOI: 10.1002/ange.201510938] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Martin R. M. Koos
- Institut für Organische Chemie und Institut für Biologische, Grenzflächen 4 - Magnetische Resonanz; Karlsruher Institut für Technologie (KIT); Fritz-Haber-Weg 6 76131 Karlsruhe Deutschland
| | - Grit Kummerlöwe
- Institut für Organische Chemie; Technische Universität München; Lichtenbergstraße 4 85747 Garching Deutschland
| | - Lukas Kaltschnee
- Clemens-Schöpf-Institut für Organische Chemie und Biochemie; Technische Universität Darmstadt; Alarich-Weiss-Straße 16 64287 Darmstadt Deutschland
| | - Christina M. Thiele
- Clemens-Schöpf-Institut für Organische Chemie und Biochemie; Technische Universität Darmstadt; Alarich-Weiss-Straße 16 64287 Darmstadt Deutschland
| | - Burkhard Luy
- Institut für Organische Chemie und Institut für Biologische, Grenzflächen 4 - Magnetische Resonanz; Karlsruher Institut für Technologie (KIT); Fritz-Haber-Weg 6 76131 Karlsruhe Deutschland
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29
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Köcher SS, Heydenreich T, Zhang Y, Reddy GNM, Caldarelli S, Yuan H, Glaser SJ. Time-optimal excitation of maximum quantum coherence: Physical limits and pulse sequences. J Chem Phys 2016; 144:164103. [DOI: 10.1063/1.4945781] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Affiliation(s)
- S. S. Köcher
- Department of Chemistry, Technische Universität München, Lichtenbergstrasse 4, D-85747 Garching, Germany
- Institute of Energy and Climate Research (IEK-9), Forschungszentrum Jülich, D-52425 Jülich, Germany
| | - T. Heydenreich
- Department of Chemistry, Technische Universität München, Lichtenbergstrasse 4, D-85747 Garching, Germany
| | - Y. Zhang
- Department of Chemistry, Technische Universität München, Lichtenbergstrasse 4, D-85747 Garching, Germany
| | - G. N. M. Reddy
- Aix Marseille Université, Centrale Marseille, CNRS, iSm2 UMR 7313, 13397 Marseille, France
| | - S. Caldarelli
- Aix Marseille Université, Centrale Marseille, CNRS, iSm2 UMR 7313, 13397 Marseille, France
| | - H. Yuan
- Department of Mechanical and Automation Engineering, Chinese University of Hong Kong, Shatin, Hong Kong, China
| | - S. J. Glaser
- Department of Chemistry, Technische Universität München, Lichtenbergstrasse 4, D-85747 Garching, Germany
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30
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Khaneja N, Dubey A, Atreya HS. Ultra broadband NMR spectroscopy using multiple rotating frame technique. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2016; 265:117-128. [PMID: 26896867 DOI: 10.1016/j.jmr.2016.02.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/31/2015] [Revised: 02/06/2016] [Accepted: 02/08/2016] [Indexed: 06/05/2023]
Abstract
The paper describes the design of broadband excitation and inversion pulses by method of multiple rotating frame technique. The ideal situation for perfect excitation and inversion is to have no chemical shift offset and thereby everything on resonance. However, when chemical shifts span a wide range, this condition is not realized. We achieve this condition using a multiply modulated rf-field, whose effect can be understood by progressing into multiple frames. As we progress through the frames, the ratio of chemical shift dispersion to strength of static rf-field decreases, resulting in a final frame, where there is negligible chemical shift as compared to the effective rf-field and we get good excitation and inversion. Increasing the number of frames, increases excitation bandwidth and the ratio of bandwidth to rms excitation amplitude. We show, in principle, it is possible to excite arbitrary large bandwidth for a given rms rf-amplitude by increasing the number of frames. The time of excitation increases linearly with the bandwidth when we keep the rms rf-amplitude constant. Experimental demonstration of proposed method is presented on (1)H excitation over a bandwidth of 52 kHz with a rms amplitude of 10 kHz. Increasing the frames increases excitation bandwidth for same rms amplitude of 10 kHz. Experimental spectra obtained from 100%(13)C labeled arginine shows uniform excitation over the entire carbon spectra, obtained with a 8-frame pulse sequence.
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Affiliation(s)
- Navin Khaneja
- Department of Electrical Engineering, IIT Bombay, Powai 400076, India.
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31
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Becker J, Luy B. CLIP-ASAP-HSQC for fast and accurate extraction of one-bond couplings from isotropic and partially aligned molecules. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2015; 53:878-885. [PMID: 26137959 DOI: 10.1002/mrc.4276] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/03/2015] [Revised: 05/07/2015] [Accepted: 05/12/2015] [Indexed: 06/04/2023]
Abstract
Fast measurement of heteronuclear one-bond couplings, a class of NMR parameters valuable for structure elucidation, is highly desirable, especially if samples undergo chemical reactions or dynamic processes are observed. Methods presented so far face severe limitations in terms of resolution, accessible bandwidth, and sensitivity. We present the CLean InPhase-Acceleration by Sharing Adjacent Polarization-HSQC (CLIP-ASAP-HSQC) pulse sequence that allows fast acquisition of spectra with clean inphase multiplets in about 25 s. The performance in terms of accurate extraction of one-bond couplings is demonstrated on three test samples including partially aligned molecules.
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Affiliation(s)
- Johanna Becker
- Karlsruhe Institute of Technology (KIT), Institute for Biological Interfaces 4 - Magnetic Resonance, Eggenstein-Leopoldshafen, Germany
| | - Burkhard Luy
- Karlsruhe Institute of Technology (KIT), Institute for Biological Interfaces 4 - Magnetic Resonance, Eggenstein-Leopoldshafen, Germany
- Karlsruhe Institute of Technology (KIT), Institute of Organic Chemistry, Karlsruhe, Germany
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32
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Koos MRM, Feyrer H, Luy B. Broadband excitation pulses with variable RF amplitude-dependent flip angle (RADFA). MAGNETIC RESONANCE IN CHEMISTRY : MRC 2015; 53:886-893. [PMID: 26259565 DOI: 10.1002/mrc.4297] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/19/2015] [Revised: 06/02/2015] [Accepted: 06/18/2015] [Indexed: 06/04/2023]
Abstract
Pulse sequences in NMR spectroscopy sometimes require the adjustment of effective flip angles with respect to experiment-specific or sample-specific parameters. Here, we present a quality factor for efficient optimization of offset-compensated broadband excitation pulses with RF amplitude-dependent effective flip angles (RADFA). After proof of principle, physical limits of RF amplitude-restricted and RF power-restricted broadband RADFA pulses are explored and corresponding pulse shapes and performances characterized in detail.
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Affiliation(s)
- Martin R M Koos
- Institut für Biologische Grenzflächen, Karlsruher Institut für Technologie (KIT), Postfach 3640, 76021 Karlsruhe, Germany
| | - Hannes Feyrer
- Institut für Organische Chemie, Karlsruher Institut für Technologie (KIT), Fritz-Haber-Weg 6, 76131 Karlsruhe, Germany
| | - Burkhard Luy
- Institut für Biologische Grenzflächen, Karlsruher Institut für Technologie (KIT), Postfach 3640, 76021 Karlsruhe, Germany
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33
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Ehni S, Luy B. Robust INEPT and refocused INEPT transfer with compensation of a wide range of couplings, offsets, and B1-field inhomogeneities (COB3). JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2014; 247:111-117. [PMID: 25245402 DOI: 10.1016/j.jmr.2014.07.010] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2014] [Revised: 07/14/2014] [Accepted: 07/15/2014] [Indexed: 06/03/2023]
Abstract
Following the two-step optimization procedure previously introduced with the COB-INEPT (Ehni and Luy, 2012), a corresponding inphase-to-antiphase transfer element with close to optimal transfer efficiencies over a coupling range comprising approximately J-6J has been derived. The hard pulse sequence length is only 5.5 ms for coupling constants within 125-750 Hz. Robustness with respect to an offset range of 37.5 kHz on carbon (corresponding to 250 ppm on a 600 MHz spectrometer) and 10 kHz on protons (16.6 ppm at 600 MHz) is achieved with corresponding BUBI and BURBOP broadband pulses. As the sequence achieves a three times higher upper limit of J-compensation compared to the COB-INEPT, we name the transfer element COB3-INEPT. Next to the description of optimization and pulse sequence details, the performance of the resulting element is demonstrated on a test sample and partially aligned sample with actual total couplings in the range of 134 Hz⩽(1)TCH⩽391 Hz. The sequence can also be used for inphase-to-antiphase transfer starting from carbon, where the upper limit of J-compensation is 6J for CH-groups, 3J for CH2-groups, and slightly less than 2J for CH3. Theoretical transfers and experimental verification for the different multiplicities in an refocused INEPT are given.
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Affiliation(s)
- Sebastian Ehni
- Institute of Organic Chemistry and Institute for Biological Interfaces, Karlsruhe Institute of Technology (KIT), Fritz-Haber-Weg 6, 76131 Karlsruhe, Germany
| | - Burkhard Luy
- Institute of Organic Chemistry and Institute for Biological Interfaces, Karlsruhe Institute of Technology (KIT), Fritz-Haber-Weg 6, 76131 Karlsruhe, Germany.
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34
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Mandal S, Borneman TW, Koroleva VDM, Hürlimann MD. Direct optimization of signal-to-noise ratio of CPMG-like sequences in inhomogeneous fields. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2014; 247:54-66. [PMID: 25241006 DOI: 10.1016/j.jmr.2014.08.012] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/09/2014] [Revised: 08/20/2014] [Accepted: 08/21/2014] [Indexed: 06/03/2023]
Abstract
The performance of the standard CPMG sequence in inhomogeneous fields can be improved with the use of broadband excitation and refocusing pulses. In previous work we have developed short composite broadband refocusing pulses together with practical excitation pulses to realize such performance gains, and quantified them using the ratio of signal to noise power (SNR). In this work we systematically explore the performance of refocusing pulses as a function of the overall pulse length up to ten times the length of the regular 180° pulse. This is in the regime of non-adiabatic pulses. We introduce a new performance functional for numerical pulse optimization that directly maximizes SNR and study the effect of symmetry constraints on the pulses. We find that for the optimal pulses, the SNR per asymptotic echo increases with pulse length but, for typical echo spacings, the SNR per unit time is maximized for refocusing pulses that are between two and four times longer than the duration of the standard rectangular 180° pulse. The performance is limited by the control bandwidth and the inability of finding the global maximum. The best performance was obtained with symmetric phase-alternating (SPA) refocusing pulses optimized with our novel performance functional. To test them in the CPMG sequence, we also developed axis-matching excitation (AMEX) pulses for use with these SPA refocusing pulses and tested the new AMEX-SPA sequences experimentally in a grossly inhomogeneous field, observing excellent agreement with the theoretical expectations. One of these sequences produced over 4.5 times higher SNR per asymptotic echo and 3.9 times higher SNR per unit time than the standard CPMG sequence with the same instantaneous RF power level. We also found that the new sequences are at least as robust to changes in the RF field strength as the standard CPMG sequence.
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Affiliation(s)
- Soumyajit Mandal
- Schlumberger-Doll Research, One Hampshire Street, Cambridge, MA 02139, United States
| | - Troy W Borneman
- Institute for Quantum Computing, 200 University Ave. W., Waterloo, ON N2L 3G1, Canada; Department of Physics and Astronomy, University of Waterloo, Waterloo, ON N2L 3G1, Canada
| | - Van D M Koroleva
- Schlumberger-Doll Research, One Hampshire Street, Cambridge, MA 02139, United States; School of Engineering and Applied Sciences, Harvard University, 33 Oxford Street, Cambridge, MA 02138, United States
| | - Martin D Hürlimann
- Schlumberger-Doll Research, One Hampshire Street, Cambridge, MA 02139, United States.
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35
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Wei D, Spörl A, Chang Y, Khaneja N, Yang X, Glaser SJ. Time-optimized quantum gates on linear three-qubit systems with indirect Ising coupling. Chem Phys Lett 2014. [DOI: 10.1016/j.cplett.2014.08.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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36
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Enders M, Görling B, Braun AB, Seltenreich JE, Reichenbach LF, Rissanen K, Nieger M, Luy B, Schepers U, Bräse S. Cytotoxicity and NMR Studies of Platinum Complexes with Cyclooctadiene Ligands. Organometallics 2014. [DOI: 10.1021/om500540x] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Mirja Enders
- Institute
of Organic Chemistry, Karlsruhe Institute of Technology (KIT), Fritz-Haber-Weg 6, D-76131 Karlsruhe, Germany
| | - Benjamin Görling
- Institute
of Organic Chemistry, Karlsruhe Institute of Technology (KIT), Fritz-Haber-Weg 6, D-76131 Karlsruhe, Germany
| | - Alexander B. Braun
- Institute
of Organic Chemistry, Karlsruhe Institute of Technology (KIT), Fritz-Haber-Weg 6, D-76131 Karlsruhe, Germany
| | - Judith E. Seltenreich
- Institute
of Toxicology and Genetics, Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, D-76344 Eggenstein-Leopoldshafen, Germany
| | - Linus F. Reichenbach
- Institute
of Organic Chemistry, Karlsruhe Institute of Technology (KIT), Fritz-Haber-Weg 6, D-76131 Karlsruhe, Germany
| | - Kari Rissanen
- Department
of Chemistry, University of Jyväskylä, P.O. Box 35, 40014 Jyväskylä, Finland
| | - Martin Nieger
- Laboratory
of Inorganic Chemistry, Department of Chemistry, University of Helsinki, P.O. Box 55, A.I. Virtasen aukio 1, 00014 University of Helsinki, Finland
| | - Burkhard Luy
- Institute
of Organic Chemistry, Karlsruhe Institute of Technology (KIT), Fritz-Haber-Weg 6, D-76131 Karlsruhe, Germany
- Institute
for Biological Interfaces II, Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, D-76344 Eggenstein-Leopoldshafen, Germany
| | - Ute Schepers
- Institute
of Toxicology and Genetics, Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, D-76344 Eggenstein-Leopoldshafen, Germany
| | - Stefan Bräse
- Institute
of Organic Chemistry, Karlsruhe Institute of Technology (KIT), Fritz-Haber-Weg 6, D-76131 Karlsruhe, Germany
- Institute
for Biological Interfaces II, Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, D-76344 Eggenstein-Leopoldshafen, Germany
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37
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Marchione AA, Dooley RJ, Conklin B. Comparison of 1H-19F two-dimensional NMR scalar coupling correlation pulse sequences. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2014; 52:183-189. [PMID: 24535754 DOI: 10.1002/mrc.4052] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/17/2013] [Revised: 01/06/2014] [Accepted: 01/18/2014] [Indexed: 06/03/2023]
Abstract
The effectiveness of hetero-COSY, HETCOR, HMQC, and HSQC two-dimensional NMR pulse sequences for detection of (19)F-(1)H correlations by scalar coupling was evaluated on monofluorinated and polyfluorinated test compounds. All four of these sequences were effective in observing (1)H-(19)F correlations, using either (19) F or (1)H as the observe nucleus. All four sequences were amenable, to some degree, to adjustment to observe larger or smaller couplings preferentially. A 1/2J echo filter was effectively applied to remove artifacts from (2)JFF strong coupling. The HETCOR experiments afforded the best overall combination of sensitivity, resolution and selectivity for JHF.
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38
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Reinsperger T, Luy B. Homonuclear BIRD-decoupled spectra for measuring one-bond couplings with highest resolution: CLIP/CLAP-RESET and constant-time-CLIP/CLAP-RESET. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2014; 239:110-120. [PMID: 24365099 DOI: 10.1016/j.jmr.2013.11.015] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2013] [Revised: 11/22/2013] [Accepted: 11/23/2013] [Indexed: 06/03/2023]
Abstract
Heteronuclear one-bond couplings are of interest for various aspects of structural analysis of small organic molecules, including for example the distinction of axial and equatorial protons or the use of RDCs as angular constraints. Such couplings are most easily measured from pure doublets in HSQC-type spectra. Recently, the fully decoupled RESET HSQC experiment was reported and several other so-called pure-shift methods followed that allow for the removal of splittings due to homonuclear scalar interactions in one and two-dimensional NMR. In this work we present broadband homonuclear decoupled CLIP/CLAP-RESET experiments based on an isotope-selective BIRD filter element using a recently reported improved version of Zangger-Sterk data chunking. The concatenated FIDs result in multiplets in which most homonuclear splittings are removed while the heteronuclear one-bond couplings are retained. Couplings can be extracted in an IPAP fashion without scaling of subspectra by the use of optimized coherence transfer elements like the COB-INEPT. The method leads to complete homonuclear decoupling for CH groups and CH3 groups in isotropic samples, but leaves residual splittings with antiphase contributions for e.g. CH2 groups due to (2)JHH coupling evolution that is not affected by the BIRD element. For this case we present a constant-time version of the proposed BIRD decoupling scheme with full homonuclear decoupling. In addition, the effects of strong coupling are discussed. Strong coupling artifacts cannot be circumvented, but the proposed experiments allow their distinct recognition.
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Affiliation(s)
- Tony Reinsperger
- Institut für Biologische Grenzflächen, Karlsruher Institut für Technologie (KIT), Postfach 3640, 76021 Karlsruhe, Germany; Institut für Organische Chemie, Karlsruher Institut für Technologie (KIT), Fritz-Haber-Weg 6, 76131 Karlsruhe, Germany
| | - Burkhard Luy
- Institut für Biologische Grenzflächen, Karlsruher Institut für Technologie (KIT), Postfach 3640, 76021 Karlsruhe, Germany; Institut für Organische Chemie, Karlsruher Institut für Technologie (KIT), Fritz-Haber-Weg 6, 76131 Karlsruhe, Germany.
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39
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Schulze-Sünninghausen D, Becker J, Luy B. Rapid heteronuclear single quantum correlation NMR spectra at natural abundance. J Am Chem Soc 2014; 136:1242-5. [PMID: 24417402 DOI: 10.1021/ja411588d] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A novel NMR experiment, the so-called ASAP-HSQC, is introduced that allows the detection of heteronuclear one-bond correlations in less than 30 s on small molecules at natural abundance without compromises in sweep width, resolution or spectral quality. Equally, the experiment allows a significant increase in digital resolution or a moderate senstitivity enhancement in the same overall experiment time compared to a conventional HSQC. The gain is a consequence of keeping all unused proton magnetization along z during acquisition, so that the previously reported ASAP and ALSOFAST approaches can be transferred from HMQC to HSQC-type experiments. Next to basic and broadband pulse sequences, a characterization of the sequence with respect to minimum measurement time, sensitivity gain, and advantages in resolution compared to state-of-the-art experiments is given.
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Affiliation(s)
- David Schulze-Sünninghausen
- Institut für Organische Chemie and Institut für Biologische Grenzflächen, Karlsruher Institut für Technologie (KIT) , Fritz-Haber-Weg 6, 76131 Karlsruhe, Germany
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40
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Mandal S, Koroleva VDM, Borneman TW, Song YQ, Hürlimann MD. Axis-matching excitation pulses for CPMG-like sequences in inhomogeneous fields. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2013; 237:1-10. [PMID: 24125955 DOI: 10.1016/j.jmr.2013.09.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2013] [Revised: 09/06/2013] [Accepted: 09/08/2013] [Indexed: 06/02/2023]
Abstract
The performance of the standard CPMG sequence in inhomogeneous fields can be improved with the use of broadband excitation and refocusing pulses. Here we introduce a new class of excitation pulses, so-called axis-matching excitation pulses, that optimize the response for a given refocusing pulse. These new excitation pulses are tailored to the refocusing pulses and take their imperfections into account. Rather than generating purely transverse magnetization, these pulses are designed to generate magnetization pointing along the axis of the effective rotation of the refocusing cycle. This approach maximizes the CPMG component and minimizes the CP component of the signal. Replacing a standard 90° pulse with a new excitation pulse matched to the 180° refocusing pulse increases the signal bandwidth and improves the echo amplitudes by 30% in inhomogeneous fields in comparison to the standard CPMG sequence. Larger gains are obtained with more advanced refocusing pulses. Recent work demonstrated that it is possible to increase the signal to noise ratio (SNR) of individual echoes by more than a factor of 1.5 (in power units) without increasing the duration or amplitude of the refocusing pulses. This was achieved by replacing the standard 180° refocusing pulse by a short phase alternating pulse and the standard 90° excitation pulse by a broadband excitation pulse. We show here that with suitable axis-matching excitation pulses, the SNR further increases by over a factor of 2. We discuss the underlying theory and present several practical implementations of purely phase modulated axis-matching excitation pulses for a number of different refocusing pulses that were derived using methods of optimal control. To gain the full benefit of these new excitation pulses, it is essential to replace the standard phase cycling scheme based on 180° phase shifts by a new scheme involving phase inversion. We tested the new pulses experimentally and observe excellent agreement with the theoretical expectations. We also demonstrate that an additional benefit of axis-matching excitation pulses is the decrease of the transient that appears in the amplitudes of the first few echoes, thus enabling better measurements of short relaxation times.
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Affiliation(s)
- Soumyajit Mandal
- Schlumberger-Doll Research, One Hampshire Street, Cambridge, MA 02139, United States
| | - Van D M Koroleva
- Schlumberger-Doll Research, One Hampshire Street, Cambridge, MA 02139, United States; School of Engineering and Applied Sciences, Harvard University, 33 Oxford Street, Cambridge, MA 02138, United States
| | - Troy W Borneman
- Schlumberger-Doll Research, One Hampshire Street, Cambridge, MA 02139, United States; Institute for Quantum Computing, 200 University Ave. W., Waterloo, ON N2L 3G1, Canada; Department of Physics and Astronomy, University of Waterloo, Waterloo, ON N2L 3G1, Canada
| | - Yi-Qiao Song
- Schlumberger-Doll Research, One Hampshire Street, Cambridge, MA 02139, United States
| | - Martin D Hürlimann
- Schlumberger-Doll Research, One Hampshire Street, Cambridge, MA 02139, United States.
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41
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Jakubczyk D, Merle C, Brenner-Weiss G, Luy B, Bräse S. Deuterium and Tritium Labelling ofN-Acyl-L-homoserine Lactones (AHLs) by Catalytic Reduction of a Double Bond in the Layer-by-Layer Method. European J Org Chem 2013. [DOI: 10.1002/ejoc.201300084] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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42
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Ehni S, Luy B. BEBE(tr) and BUBI: J-compensated concurrent shaped pulses for 1H-13C experiments. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2013; 232:7-17. [PMID: 23673080 DOI: 10.1016/j.jmr.2013.04.007] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2013] [Revised: 03/22/2013] [Accepted: 04/12/2013] [Indexed: 06/02/2023]
Abstract
Shaped pulses designed for broadband excitation, inversion and refocusing are important tools in modern NMR spectroscopy to achieve robust pulse sequences especially in heteronuclear correlation experiments. A large variety of mostly computer-optimized pulse shapes exist for different desired bandwidths, available rf-field strengths, and tolerance to B1-inhomogeneity. They are usually derived for a single spin 1/2, neglecting evolution due to J-couplings. While pulses with constant resulting phase are selfcompensated for heteronuclear coupling evolution as long as they are applied exclusively on a single nucleus, the situation changes for concurrently applied pulse shapes. Using the example of a (1)H,(13)C two spin system, two J-compensated pulse pairs for the application in INEPT-type transfer elements were optimized: a point-to-point pulse sandwich called BEBE(tr), consisting of a broadband excitation and time-reversed excitation pulse, and a combined universal rotation and point-to-point pulse pair called BUBI, which acts as a refocusing pulse on (1)H and a corresponding inversion pulse on (13)C. After a derivation of quality factors and optimization protocols, a theoretical and experimental comparison with conventionally derived BEBOP, BIBOP, and BURBOP-180° pulses is given. While the overall transfer efficiency of a single pulse pair is only reduced by approximately 0.1%, resulting transfer to undesired coherences is reduced by several percent. In experiments this can lead to undesired phase distortions for pairs of uncompensated pulse shapes and even differences in signal intensities of 5-10% in HSQC and up to 68% in more complex COB-HSQC experiments.
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Affiliation(s)
- Sebastian Ehni
- Institute of Organic Chemistry and Institute for Biological Interfaces, Karlsruhe Institute of Technology (KIT), Fritz-Haber-Weg 6, 76131 Karlsruhe, Germany
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43
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Trigo-Mouriño P, Merle C, Koos MRM, Luy B, Gil RR. Probing Spatial Distribution of Alignment by Deuterium NMR Imaging. Chemistry 2013; 19:7013-9. [DOI: 10.1002/chem.201300254] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2013] [Indexed: 11/09/2022]
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44
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Nimbalkar M, Luy B, Skinner TE, Neves JL, Gershenzon NI, Kobzar K, Bermel W, Glaser SJ. The Fantastic Four: A plug 'n' play set of optimal control pulses for enhancing NMR spectroscopy. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2013; 228:16-31. [PMID: 23333616 DOI: 10.1016/j.jmr.2012.12.007] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/09/2012] [Revised: 12/05/2012] [Accepted: 12/11/2012] [Indexed: 06/01/2023]
Abstract
We present highly robust, optimal control-based shaped pulses designed to replace all 90° and 180° hard pulses in a given pulse sequence for improved performance. Special attention was devoted to ensuring that the pulses can be simply substituted in a one-to-one fashion for the original hard pulses without any additional modification of the existing sequence. The set of four pulses for each nucleus therefore consists of 90° and 180° point-to-point (PP) and universal rotation (UR) pulses of identical duration. These 1ms pulses provide uniform performance over resonance offsets of 20kHz ((1)H) and 35kHz ((13)C) and tolerate reasonably large radio frequency (RF) inhomogeneity/miscalibration of ±15% ((1)H) and ±10% ((13)C), making them especially suitable for NMR of small-to-medium-sized molecules (for which relaxation effects during the pulse are negligible) at an accessible and widely utilized spectrometer field strength of 600MHz. The experimental performance of conventional hard-pulse sequences is shown to be greatly improved by incorporating the new pulses, each set referred to as the Fantastic Four (Fanta4).
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Affiliation(s)
- Manoj Nimbalkar
- Department of Chemistry, Technische Universität München, Lichtenbergstrasse 4, D-85747 Garching, Germany.
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Assémat E, Lapert M, Sugny D, J. Glaser S. On the application of geometric optimal control theory to Nuclear Magnetic Resonance. ACTA ACUST UNITED AC 2013. [DOI: 10.3934/mcrf.2013.3.375] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Ehni S, Luy B. A systematic approach for optimizing the robustness of pulse sequence elements with respect to couplings, offsets, and B1-field inhomogeneities (COB). MAGNETIC RESONANCE IN CHEMISTRY : MRC 2012; 50 Suppl 1:S63-S72. [PMID: 23280662 DOI: 10.1002/mrc.3846] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2012] [Revised: 06/21/2012] [Accepted: 06/21/2012] [Indexed: 06/01/2023]
Abstract
Robust experiments that cover a wide range of chemical shift offsets and J-couplings are highly desirable for a multitude of applications in small molecule NMR spectroscopy. Many attempts to improve individual aspects of the robustness of pulse sequence elements based on rational and numerical design have been reported, but a general optimization strategy to cover all necessary aspects for a fully robust sequence is still lacking. In this article, a viable optimization strategy is introduced that covers a defined range of couplings, offsets, and B(1)-field inhomogeneities (COB) in a time-optimal way. Individual components of the optimization strategy can be optimized in any adequate way. As an example for the COB approach, we present the (1)H -(13)C-COB-INEPT with transfer of approximately 99% over the full carbon and proton bandwidth and (1)J(CH) -couplings in the range of 120-250 Hz, which have been optimized using efficient algorithms derived from optimal control theory. The theoretical performance is demonstrated in a number of corresponding COB-HSQC experiments.
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Affiliation(s)
- Sebastian Ehni
- Institute of Organic Chemistry and Institute for Biological Interfaces, Karlsruhe Institute of Technology, Fritz-Haber-Weg 6, 76131 Karlsruhe, Germany
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Kobzar K, Ehni S, Skinner TE, Glaser SJ, Luy B. Exploring the limits of broadband 90° and 180° universal rotation pulses. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2012; 225:142-160. [PMID: 23142001 DOI: 10.1016/j.jmr.2012.09.013] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2012] [Accepted: 09/28/2012] [Indexed: 06/01/2023]
Abstract
90° and 180° universal rotation (UR) pulses are two of the most important classes of pulses in modern NMR spectroscopy. This article presents a systematic study characterizing the achievable performance of these pulses as functions of bandwidth, pulse length, and tolerance to B(1)-field inhomogeneity/miscalibration. After an evaluation of different quality factors employed in pulse design algorithms based on optimal control theory, resulting pulses are discussed in detail with a special focus on pulse symmetry. The vast majority of resulting BURBOP (broadband universal rotations by optimal control) pulses are either fully symmetric or have one symmetric and one antisymmetric Cartesian rf component, where the importance of the first symmetry has not been demonstrated yet and the latter one matches the symmetry that results from a previously derived construction principle of universal rotation pulses out of point-to-point pulses [3]. Optimized BURBOP pulses are shown to perform better than previously reported UR pulses, resulting in shorter pulse durations for the same quality of broadband rotations. From a comparison of qualities of effective universal rotations, we find that the application of a single optimal refocusing pulse matches or improves the performance of two consecutive inversion pulses in INEPT-like pulse sequence elements of the same total duration.
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Affiliation(s)
- Kyryl Kobzar
- Bruker Biospin GmbH, Silberstreifen 4, 76287 Rheinstetten, Germany
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Schilling F, Glaser SJ. Tailored real-time scaling of heteronuclear couplings. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2012; 223:207-218. [PMID: 22982752 DOI: 10.1016/j.jmr.2012.07.024] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/19/2012] [Revised: 07/21/2012] [Accepted: 07/31/2012] [Indexed: 06/01/2023]
Abstract
Heteronuclear couplings are a valuable source of molecular information, which is measured from the multiplet splittings of an NMR spectrum. Radiofrequency irradiation on one coupled nuclear spin allows to modify the effective coupling constant, scaling down the multiplet splittings in the spectrum observed at the resonance frequency of the other nuclear spin. Such decoupling sequences are often used to collapse a multiplet into a singlet and can therefore simplify NMR spectra significantly. Continuous-wave (cw) decoupling has an intrinsic non-linear offset dependence of the scaling of the effective J-coupling constant. Using optimal control pulse optimization, we show that virtually arbitrary off-resonance scaling of the J-coupling constant can be achieved. The new class of tailored decoupling pulses is named SHOT (Scaling of Heteronuclear couplings by Optimal Tracking). Complementing cw irradiation, SHOT pulses offer an alternative approach of encoding chemical shift information indirectly through off-resonance decoupling, which however makes it possible for the first time to achieve linear J scaling as a function of offset frequency. For a simple mixture of eight aromatic compounds, it is demonstrated experimentally that a 1D-SHOT {(1)H}-(13)C experiment yields comparable information to a 2D-HSQC and can give full assignment of all coupled spins.
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Affiliation(s)
- Franz Schilling
- Department of Chemistry, Technische Universität München, 85747 Garching, Germany
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Lakomek NA, Ying J, Bax A. Measurement of ¹⁵N relaxation rates in perdeuterated proteins by TROSY-based methods. JOURNAL OF BIOMOLECULAR NMR 2012; 53:209-21. [PMID: 22689066 PMCID: PMC3412688 DOI: 10.1007/s10858-012-9626-5] [Citation(s) in RCA: 145] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/04/2012] [Accepted: 04/04/2012] [Indexed: 05/11/2023]
Abstract
While extracting dynamics parameters from backbone (15)N relaxation measurements in proteins has become routine over the past two decades, it is increasingly recognized that accurate quantitative analysis can remain limited by the potential presence of systematic errors associated with the measurement of (15)N R(1) and R(2) or R(1ρ) relaxation rates as well as heteronuclear (15)N-{(1)H} NOE values. We show that systematic errors in such measurements can be far larger than the statistical error derived from either the observed signal-to-noise ratio, or from the reproducibility of the measurement. Unless special precautions are taken, the problem of systematic errors is shown to be particularly acute in perdeuterated systems, and even more so when TROSY instead of HSQC elements are used to read out the (15)N magnetization through the NMR-sensitive (1)H nucleus. A discussion of the most common sources of systematic errors is presented, as well as TROSY-based pulse schemes that appear free of systematic errors to the level of <1 %. Application to the small perdeuterated protein GB3, which yields exceptionally high S/N and therefore is an ideal test molecule for detection of systematic errors, yields relaxation rates that show considerably less residue by residue variation than previous measurements. Measured R(2)'/R(1)' ratios fit an axially symmetric diffusion tensor with a Pearson's correlation coefficient of 0.97, comparable to fits obtained for backbone amide RDCs to the Saupe matrix.
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Affiliation(s)
| | | | - Ad Bax
- Correspondence: Ad Bax, National Institutes of Health, DHHS NIDDK LCP, Building 5, Room 126, 9000 Rockville Pike, Bethesda, MD 20892-0520, Tel.:301-496-2848, Fax: 301-402-0907,
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Skinner TE, Gershenzon NI, Nimbalkar M, Glaser SJ. Optimal control design of band-selective excitation pulses that accommodate relaxation and RF inhomogeneity. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2012; 217:53-60. [PMID: 22425442 DOI: 10.1016/j.jmr.2012.02.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2011] [Revised: 02/11/2012] [Accepted: 02/14/2012] [Indexed: 05/31/2023]
Abstract
Existing optimal control protocols for mitigating the effects of relaxation and/or RF inhomogeneity on broadband pulse performance are extended to the more difficult problem of designing robust, refocused, frequency selective excitation pulses. For the demanding case of T(1) and T(2) equal to the pulse length, anticipated signal losses can be significantly reduced while achieving nearly ideal frequency selectivity. Improvements in performance are the result of allowing residual unrefocused magnetization after applying relaxation-compensated selective excitation by optimized pulses (RC-SEBOPs). We demonstrate simple pulse sequence elements for eliminating this unwanted residual signal.
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Affiliation(s)
- Thomas E Skinner
- Physics Department, Wright State University, Dayton, OH 45435, USA.
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