Jul 22, 2019

19F Magic Angle Spinning Dynamic Nuclear Polarization Enhanced NMR Spectroscopy #DNPNMR

Viger-Gravel, Jasmine, Claudia E. Avalos, Dominik J. Kubicki, David Gajan, Moreno Lelli, Olivier Ouari, Anne Lesage, and Lyndon Emsley. “19F Magic Angle Spinning Dynamic Nuclear Polarization Enhanced NMR Spectroscopy.” Angewandte Chemie International Edition 58, no. 22 (May 27, 2019): 7249–53.

The introduction of high frequency, high power microwave sources, tailored biradicals, and low-temperature magic- 30 angle spinning probes has led to a rapid development of hyperpolarization strategies for solids and frozen solutions, leading to large gains in NMR sensitivity. Here, we introduce a protocol for efficient hyperpolarization of 19F nuclei in MAS DNP enhanced NMR. We identify trifluoroethanol-d3 as a versatile glassy matrix and show that 12 mM AMUPol (with microcrystalline KBr) provides direct 19F DNP enhancements of over 100 at 9.4 T. We apply this protocol to 10 obtain DNP-enhanced 19F and 19F-13C cross-polarization (CP) spectra for an active pharmaceutical ingredient and a fluorinated mesostructured hybrid material, using incipient wetness 40 impregnation with enhancements of ~25 and ~10 in the bulk solid, respectively. This strategy is a general and straightforward method for obtaining enhanced 19F MAS spectra from fluorinated materials.

Jul 19, 2019

1H high field electron-nuclear double resonance spectroscopy at 263 GHz/9.4 T

Tkach, Igor, Isabel Bejenke, Fabian Hecker, Annemarie Kehl, Müge Kasanmascheff, Igor Gromov, Ion Prisecaru, Peter Höfer, Markus Hiller, and Marina Bennati. “1H High Field Electron-Nuclear Double Resonance Spectroscopy at 263 GHz/9.4 T.” Journal of Magnetic Resonance 303 (June 2019): 17–27.

We present and discuss the performance of 1H electron-nuclear double resonance (ENDOR) at 263 GHz/9.4 Tesla by employing a prototype, commercial quasi optical spectrometer. Basic instrumental features of the setup are described alongside a comprehensive characterization of the new ENDOR probe head design. The performance of three different ENDOR pulse sequences (Davies, Mims and CP-ENDOR) is evaluated using the 1H BDPA radical. A key feature of 263 GHz spectroscopy – the increase in orientiation selectivity in comparison with 94 GHz experiments – is discussed in detail. For this purpose, the resolution of 1H ENDOR spectra at 263 GHz is verified using a representative protein sample containing approximately 15 picomoles of a tyrosyl radical. Davies ENDOR spectra recorded at 5 K reveal previously obscured spectral features, which are interpreted by spectral simulations aided by DFT calculations. Our analysis shows that seven internal proton couplings are detectable for this specific radical if sufficient orientation selectivity is achieved. The results prove the fidelity of 263 GHz experiments in reporting orientation-selected 1H ENDOR spectra and demonstrate that new significant information can be uncovered in complex molecular systems, owing to the enhanced resolution combined with high absolute sensitivity and no compromise in acquisition time.

Jul 17, 2019

High-throughput continuous-flow system for SABRE hyperpolarization

Štěpánek, Petr, Clara Sanchez-Perez, Ville-Veikko Telkki, Vladimir V. Zhivonitko, and Anu M. Kantola. “High-Throughput Continuous-Flow System for SABRE Hyperpolarization.” Journal of Magnetic Resonance 300 (March 2019): 8–17.

Signal Amplification By Reversible Exchange (SABRE) is a versatile method for hyperpolarizing small organic molecules that helps to overcome the inherent low signal-to-noise ratio of nuclear magnetic resonance (NMR) measurements. It offers orders of magnitude enhanced signal strength, but the obtained nuclear polarization usually rapidly relaxes, requiring a quick transport of the sample to the spectrometer. Here we report a new design of a polarizing system, which can be used to prepare a continuous flow of SABREhyperpolarized sample with a considerable throughput of several mililiters per second and a rapid delivery into an NMR instrument. The polarizer performance under different conditions such as flow rate of the hydrogen or liquid sample is tested by measuring a series of NMR spectra and magnetic resonance images (MRI) of hyperpolarized pyridine in methanol. Results show a capability to continuously produce sample with dramatically enhanced signal over two orders of magnitude. The constant supply of hyperpolarized sample can be exploited, e.g., in experiments requiring multiple repetitions, such as 2D and 3D-NMR or MRI measurements, and also naturally allows measurements of flow maps, including systems with high flow rates, for which the level of achievable thermal polarization might not be usable any more. In addition, the experiments can be viably carried out in a non-deuterated solvent, due to the effective suppression of the thermal polarization by the fast sample flow. The presented system opens the possibilities for SABRE experiments requiring a long-term, stable and high level of nuclear polarization.

Jul 15, 2019

Parahydrogen induced hyperpolarization provides a tool for NMR metabolomics at nanomolar concentrations

Sellies, Lisanne, Indrek Reile, Ruud L. E. G. Aspers, Martin C. Feiters, Floris P. J. T. Rutjes, and Marco Tessari. “Parahydrogen Induced Hyperpolarization Provides a Tool for NMR Metabolomics at Nanomolar Concentrations.” Chemical Communications 55, no. 50 (2019): 7235–38.

An NMR approach based on parahydrogen hyperpolarization is presented to detect and resolve specific classes of metabolites in complex biomixtures at down to nanomolar concentrations. We demonstrate our method on solid phase extracts of urine, by simultaneously observing hundreds of metabolites well below the limits of detection of thermal NMR.

Jul 13, 2019

[NMR] Postdoctoral position at Miami University

Postdoctoral Position: EPR Spectroscopic Studies of Membrane Proteins

Miami University, Oxford, OH, USA

A Postdoctoral research position is available immediately to study the structural and dynamic properties of integral membrane proteins in the laboratory of Prof. Gary A. Lorigan in the Department of Chemistry and Biochemistry at Miami University in Ohio. The postdoctoral position is funded through a NIH MIRA R35 grant.

Candidates who are interested in studying the structural and dynamic properties of membrane proteins are encouraged to apply. Experience in two of the following areas is desirable: molecular biology and biochemistry of membrane proteins, protein purification, and EPR spectroscopy. 2 pulsed EPR spectrometers (X-band/Q-band) for DEER and ESEEM experiments, 2 CW-EPR spectrometers, and a 500 MHz solid-state NMR instrument are available for this project. Miami University is home to the Ohio Advanced EPR Lab (http://epr.miamioh.edu). Please send a CV and two letters of recommendation to: Professor Gary A. Lorigan, Department of Chemistry and Biochemistry, Miami University gary.lorigan@miamioh.edu. A Ph.D. in Chemistry/Biochemistry or related fields is required. Contact phone is 513-529-3338. 

Miami University, an Equal Opportunity/Affirmative Action employer, encourages applications from minorities, women, protected veterans and individuals with disabilities. Miami University prohibits harassment, discrimination and retaliation on the basis of sex/gender (including sexual harassment, sexual violence, sexual misconduct, domestic violence, dating violence, or stalking), race, color, religion, national origin (ancestry), disability, age (40 years or older), sexual orientation, gender identity, pregnancy, status as a parent or foster parent, military status, or veteran status in its recruitment, selection, and employment practices. Requests for all reasonable accommodations for disabilities related to employment should be directed to ADAFacultyStaff@miamioh.edu or 513-529-3560.

As part of the University’s commitment to maintaining a healthy and safe living, learning, and working environment, we encourage you to read Miami University’s Annual Security & Fire Safety Report at http://www.MiamiOH.edu/campus-safety/annual-report/index.html(http://www.miamioh.edu/campus-safety/annual-report/index.html), which contains information about campus safety, crime statistics, and our drug and alcohol abuse and prevention program designed to prevent the unlawful possession, use, and distribution of drugs and alcohol on campus and at university events and activities. This report also contains information on programs and policies designed to prevent and address sexual violence, domestic violence, dating violence, and stalking. Each year, email notification of this website is made to all faculty, staff, and enrolled students. Written notification is also provided to prospective students and employees. Hard copies of the Annual Security & Fire Safety Report may be obtained from the Miami University Police Department at (513) 529-2225.

Gary A. Lorigan
John W. Steube Professor 
Department of Chemistry and Biochemistry
Miami University
651 E. High St.
Oxford, Ohio 45056

Office: 137 Hughes Laboratories
Phone: (513) 529-3338
Fax: (513) 529-5715
EPR facility: epr.muohio.edu

This is the AMPERE MAGNETIC RESONANCE mailing list:

NMR web database:

Jul 12, 2019

Nonpentacene Polarizing Agents with Improved Air Stability for Triplet Dynamic Nuclear Polarization at Room Temperature

Kouno, Hironori, Yusuke Kawashima, Kenichiro Tateishi, Tomohiro Uesaka, Nobuo Kimizuka, and Nobuhiro Yanai. “Nonpentacene Polarizing Agents with Improved Air Stability for Triplet Dynamic Nuclear Polarization at Room Temperature.” The Journal of Physical Chemistry Letters 10, no. 9 (May 2, 2019): 2208–13.

Triplet dynamic nuclear polarization (triplet-DNP), a method to enhance the NMR and MRI sensitivity using photo-excited triplet electrons, has a great potential to hyperpolarize nuclear spins at room temperature. Since the first report of room-temperature triplet-DNP in 1990, pentacene has been the only and best option of triplet polarizing agents. However, the poor airstability of pentacene has severely limited the applicability of triplet-DNP. Here, we report the first example of polarizing agents with significant air-stability as well as high polarizing ability comparable to pentacene. The introduction of electron-withdrawing diaza-substitution to pentacene and tetracene reduces the LUMO level and endows much-improved stability under the ambient condition. Importantly, the diaza-substituted pentacene and tetracene offer similar, or even slightly better, 1H NMR signal enhancement compared with pentacene in the prototypical triplet-DNP test using p-terphenyl crystals. This work removes one of the largest obstacles towards the application of triplet-DNP for hyperpolarization of biological molecules.

Jul 10, 2019

Post-Doctoral Position characterizing functional amyloids #DNPNMR

A Post-Doctoral position is available immediately to study functional amyloid formation by Streptococcus mutans, particularly as it relates to biofilm development. The focus of this project is to characterize the ultrastructure and amyloid properties of the adhesion P1 and other amyloidogenic surface proteins utilizing solution NMR, DNP-enhanced solid state NMR, cryoelectron microscopy, and diffraction techniques to study their structure in fibrillar and nonfibrillar forms. Applicants should have a strong background in biomolecular NMR spectroscopy, molecular microbiology, and biochemistry with an emphasis on protein structure/dynamics/function. Experience with standard cloning and recombinant DNA methodologies, protein chemistry, chromatography, and heterologous protein expression and purification is necessary. Familiarity with techniques to evaluate protein-protein interactions, protein crystallization and X-ray diffraction methodologies, mass spectrometry, and electron microscopy will be given preference. Also desirable would be familiarity with assays to assess amyloid fibrillization including use of fluorescent dyes and spectral shift assays, Congo-red induced birefringence, confocal microscopy and immunogold electron microscopy.

NMR facilities include fifteen spectrometers located at UF and the National High Magnetic Field Laboratory ranging from 500-900 MHz, including a 600 MHz ssNMR instrument with DNP capabilities. Extensive facilities for protein production and purification, cryoelec­tron microscopy, x-ray crystallography, and high performance computing are in close proximity to the Brady and Long labs as part of the UF centers for structural biology and high performance computing.

A Ph.D. and English language proficiency are required. Salary is commensurate with experience and range follows NIH guidelines. This is a grant-funded position and is annually renewable based on the availability of research funds. Please contact Joanna R. Long (jrlong@ufl.edu) and L. Jeannine Brady (jbrady@dental.ufl.edu) at The University of Florida, Departments of Biochemistry & Molecular Biology and Oral Biology, respectively, with any questions. (http://biochem.med.ufl.edu/research/faculty/primary-faculty/joanna-long/ and http://www.dental.ufl.edu/Offices/Oral_Biology/faculty/Brady_Linda/).

The University of Florida is an Equal Opportunity Institution dedicated to building a culturally diverse and inclusive faculty and staff. The selection process will be conducted in accord with the provisions of Florida’s “Government in the Sunshine” and Public Records Laws.

Joanna R. Long, PhD

Professor of Biochemistry & Molecular Biology

Director, Advanced Magnetic Resonance Imaging & Spectroscopy Facility

Assoc. Director, National High Magnetic Field Laboratory

McKnight Brain Institute, LG-187

Box 100245

University of Florida

Gainesville, FL 32605


This is the AMPERE MAGNETIC RESONANCE mailing list:

NMR web database:

ReplyReply allForward