Category Archives: MAS

[NMR] 5th DNP/NMR Educational Tutorial, June 05/ Dr. Yusuke Nishiyama from JEOL

Dear NMR Enthusiast,

We are happy to announce the 5th Educational Tutorial. 

This week Dr. Yusuke Nishiyama, JEOL, Japan will talk about 

“Practical aspects of Fast MAS Solid-State NMR”.

Here are the webinar details:

Time: Friday, June 05, 2020, 07:00 AM California or 10:00 AM Boston or 4:00 PM Paris or 11:00 PM Tokyo

Join Meeting: https://ucsb.zoom.us/j/95617252728

Meeting ID: 956 1725 2728

The current format of the tutorial will consist of a 35-minute talk which will include both basic and advanced material and 25 minutes of discussion. Prof. Vipin Agarwal, TIFR Hyderabad, India will be a special panelist in the discussion session.

Please note that we have advanced the timing of (only) this session by 90 minutes for Speaker’s convenience.

Best regards,

Global NMR Discussion Meetings

PS. 

We are glad that you are liking our tutorials. In case you want to hear it again, here is the link to our previous sessions:

https://www.youtube.com/channel/UCMDyuVI6NMYzR3LByZWP4sg

Please subscribe to our YouTube channel.

[Organizers:

Adrian Draney (Guido Pintacuda Lab, CRMN lyon)

Amrit Venkatesh (Aaron Rossini Lab, Iowa)

Asif Equbal (Songi Han Lab, UCSB)

Blake Wilson (Robert Tycko Lab, NIH)

Daphna Shimon (Ilia Kaminker Lab, Tel Aviv)

Michael Hope (Lyndon Emsley Lab, EPFL)

Mona Mohammadi (Alexej Jerschow, NYU)

PinelopiMoutzouri (Lyndon Emsley Lab, EPFL) ]

====================================

This is the AMPERE MAGNETIC RESONANCE mailing list:

http://www.drorlist.com/nmrlist.html

NMR web database:

http://www.drorlist.com/nmr.html

Proton-detection in solid-state NMR to study Frustrated Lewis-Pairs #DNPNMR

The recently established research group of Dr. Thomas Wiegand is embedded in the Magnetic Resonance Research Center led by Prof. Arno Kentgens at the Institute of Molecules and Materials at Radboud University Nijmegen (The Netherlands). A central line of research in the Wiegand lab is to detect noncovalent interactions by solid-state Nuclear Magnetic Resonance spectroscopy in molecular recognition processes from both fields, materials sciences and biology. The group is focusing on unravelling catalytic reactions (e.g. hydrogenation reactions), self-assembly phenomena in the context of phase separation and protein-nucleic acid interactions. The lab is equipped with NMR spectrometers up to 850 MHz with access to the 1.2 GHz magnet installed soon in Utrecht.

The project will focus on the development and application of fast Magic-Angle Spinning experiments at > 110 kHz to detect protons which serve as highly sensitive reporters for noncovalent interactions. The student will develop an understanding of the physical origin of the residual proton linewidths at fast MAS in powdered materials as well as establish solid-state NMR approaches allowing the quantification of the strength of noncovalent interactions, e.g. hydrogen bonds. In that vein, catalytic reactions involving Frustrated Lewis-Pairs (FLPs), particularly hydrogenation reactions, will be investigated. The group has a profound knowledge in studying FLPs (typically main-group based molecules undergoing a wide variety of small molecule activation) by solid-state NMR. A further focus of the project will lie on performing Para Hydrogen Induced Polarization (PHIP) experiments to access kinetic information about such FLP-based hydrogenation reactions. The final goal is to design novel FLP-based heterogeneous catalysts and study their reactions by solid-state NMR approaches, especially also employing Dynamic Nuclear Polarization (DNP) to enhance the signal-to-noise ratios in such experiments.

The successful candidate should have a strong interest in spectroscopic techniques and in their applications to materials sciences. Basic experience in NMR is beneficial. Interest in practical work in the chemistry laboratory is expected, since the student will prepare the samples in collaboration with our partners.

Prerequisites are a Master in Chemistry, Physics, Interdisciplinary Sciences, or related areas. Applications with motivation letter, CV, university transcripts with exam grades and contact details for two academic references should be sent by email directly to Dr. Thomas Wiegand (t.wiegand@science.ru.nl). Applications will be accepted until the position is filled. The position is available from May 2020 (negotiable).

More information about the ongoing projects in the solid-state NMR lab and the hardware available can be found at https://www.ru.nl/science/magneticresonance/. Questions regarding the position should be directed to Dr. Wiegand by email.

====================================

This is the AMPERE MAGNETIC RESONANCE mailing list:

http://www.drorlist.com/nmrlist.html

NMR web database:

http://www.drorlist.com/nmr.html

[NMR] Postdoc: Solid-state NMR at 1.2 GHz

Postdoc position at ETH Zurich: for the development of fast MAS methods and biomolecular applications at high field (in particular at 1.2 GHz) in the group of Beat Meier (http://nmr.ethz.ch), we look for a postdoctoral researcher with a strong experimental background in solid-state NMR. Experience with NMR hardware and with biomolecular applications and structural biology is an asset. Spectrometers at 600 and 850 MHz are available and a 1.2 GHz system is expected in the first half of 2020.

The position is available from January 1, 2020 (or later) and is initially planned for for 1 year (renewable). Candidates should send a CV and the names of at least two references to Beat Meier (beme@ethz.ch)

====================================

This is the AMPERE MAGNETIC RESONANCE mailing list:

http://www.drorlist.com/nmrlist.html

NMR web database:

http://www.drorlist.com/nmr.html

Four millimeter spherical rotors spinning at 28 kHz with double-saddle coils for cross polarization NMR #DNPNMR

Gao, Chukun, Patrick T. Judge, Erika L. Sesti, Lauren E. Price, Nicholas Alaniva, Edward P. Saliba, Brice J. Albert, Nathan J. Soper, Pin-Hui Chen, and Alexander B. Barnes. “Four Millimeter Spherical Rotors Spinning at 28 KHz with Double-Saddle Coils for Cross Polarization NMR.” Journal of Magnetic Resonance 303 (June 2019): 1–6.

https://doi.org/10.1016/j.jmr.2019.03.006

Spherical rotors in magic angle spinning (MAS) experiments have significant advantages over traditional cylindrical rotors including simplified spinning implementation, easy sample exchange, more efficient microwave coupling for dynamic nuclear polarization (DNP), and feasibility of downscaling to access higher spinning frequencies. Here, we implement spherical rotors with 4 mm outside diameter (o.d.) and demonstrate spinning > 28 kHz using a single aperture for spinning gas. We show a modified stator geometry to improve fiber optic detection, increase NMR filling factor, and improve alignment for sample exchange and microwave irradiation. Higher NMR Rabi frequencies were obtained using smaller radiofrequency (RF) coils on small-diameter spherical rotors, compared to our previous implementation of MAS spheres with an o.d. of 9.5 mm. We report nutation fields of 110 kHz on 13C with 820 W of input power and 100 kHz on 1H with 800 W of input power. Proton decoupling fields of 78 kHz were applied over 20 ms of signal acquisition without any sign of arcing. Compared to our initial demonstration of a split coil for 9.5 mm spheres, this current implementation of a double-saddle coil inductor for 4 mm spheres not only intensifies the RF fields, but also improves RF homogeneity. We achieve an 810°/90° nutation intensity ratio of 0.84 at 300.197 MHz (1H). We also show electromagnetic simulations predicting a nearly 3-fold improvement in electron Rabi frequency of 0.99 MHz (with 4 mm spheres) compared to 0.38 MHz (with 3.2 mm cylinders), with 5 W of incident microwave power. Further improvements in magnetic resonance spin control are expected as RF inductors and microwave coupling are optimized for spherical rotors and scaled down to the micron scale.

Magic angle spinning spheres

This article is indirectly related to DNP. It describes an exciting new idea from the Barnes lab how to spin samples in a MAS-NMR experiments and the perspective of integrating DNP.

Chen, Pinhui, Brice J Albert, Chukun Gao, Nicholas Alaniva, Lauren E Price, Faith J Scott, Edward P Saliba, et al. “Magic Angle Spinning Spheres.” SCIENCE ADVANCES, 2018, 8.

https://doi.org/10.1126/sciadv.aau1540.

Magic angle spinning (MAS) is commonly used in nuclear magnetic resonance of solids to improve spectral resolution. Rather than using cylindrical rotors for MAS, we demonstrate that spherical rotors can be spun stably at the magic angle. Spherical rotors conserve valuable space in the probe head and simplify sample exchange and microwave coupling for dynamic nuclear polarization. In this current implementation of spherical rotors, a single gas stream provides bearing gas to reduce friction, drive propulsion to generate and maintain angular momentum, and variable temperature control for thermostating. Grooves are machined directly into zirconia spheres, thereby converting the rotor body into a robust turbine with high torque. We demonstrate that 9.5–mm–outside diameter spherical rotors can be spun at frequencies up to 4.6 kHz with N2(g) and 10.6 kHz with He(g). Angular stability of the spinning axis is demonstrated by observation of 79Br rotational echoes out to 10 ms from KBr packed within spherical rotors. Spinning frequency stability of ±1 Hz is achieved with resistive heating feedback control. A sample size of 36 ul can be accommodated in 9.5-mm-diameter spheres with a cylindrical hole machined along the spinning axis. We further show that spheres can be more extensively hollowed out to accommodate 161 ul of the sample, which provides superior signal-to-noise ratio compared to traditional 3.2-mm-diameter cylindrical rotors.

Magic angle spinning NMR below 6 K with a computational fluid dynamics analysis of fluid flow and temperature gradients

This article is not specifically about DNP spectroscopy. However, magic angle spinning at 6K is definitely of interest to DNP, especially when using low-power, solid-state microwave sources.

Sesti, E.L., et al., Magic angle spinning NMR below 6 K with a computational fluid dynamics analysis of fluid flow and temperature gradients. J. Magn. Reson., 2018. 286(Supplement C): p. 1-9.

http://www.sciencedirect.com/science/article/pii/S1090780717302689

We report magic angle spinning (MAS) up to 8.5 kHz with a sample temperature below 6 K using liquid helium as a variable temperature fluid. Cross polarization 13C NMR spectra exhibit exquisite sensitivity with a single transient. Remarkably, 1H saturation recovery experiments show a 1H T1 of 21 s with MAS below 6 K in the presence of trityl radicals in a glassy matrix. Leveraging the thermal spin polarization available at 4.2 K versus 298 K should result in 71 times higher signal intensity. Taking the 1H longitudinal relaxation into account, signal averaging times are therefore predicted to be expedited by a factor of >500. Computer assisted design (CAD) and finite element analysis were employed in both the design and diagnostic stages of this cryogenic MAS technology development. Computational fluid dynamics (CFD) models describing temperature gradients and fluid flow are presented. The CFD models bearing and drive gas maintained at 100 K, while a colder helium variable temperature fluid stream cools the center of a zirconia rotor. Results from the CFD were used to optimize the helium exhaust path and determine the sample temperature. This novel cryogenic experimental platform will be integrated with pulsed dynamic nuclear polarization and electron decoupling to interrogate biomolecular structure within intact human cells.

[NMR] Postdoc in biomolecular SSNMR – protein aggregation & protein-lipid interactions

Postdoctoral position in biological MAS ssNMR

The Van der Wel lab is looking for a postdoc candidate with a background in NMR, preferably solid-state NMR, to join our research effort focused on protein aggregation and protein-lipid interactions. More information on our research and recent publications can be found below and on our website at http://www.vanderwellab.org

Potentially interested parties are encouraged to email any questions and/or (informal) inquiries to vanderwel@pitt.edu

Patrick van der Wel

———————————–

Research topics: 

The researcher is expected to join the Van der Wel lab to contribute to our NIH-funded research. One focus in the lab is the use of MAS NMR to study amyloid structure and protein aggregation with a particular focus on polyglutamine-expanded proteins implicated in Huntington’s Disease. Another key focus is on the study by ssNMR of membrane structure and dynamics, as well as protein-lipid interactions, in particular in context of mitochondrial apoptosis, which has important implications for neurodegenerative disease and cancer research. 

Selected recent publications: (online access here )

  • Mandal et al. (2015) Structural Changes and Proapoptotic Peroxidase Activity of Cardiolipin-Bound Mitochondrial Cytochrome c. Biophys. J., 109(9), 1873–84.
  • Hoop et al. (2016) Huntingtin exon 1 fibrils feature an interdigitated β-hairpin-based polyglutamine core. PNAS, 113(6), 1546–51. 
  • Merg et al. (2016) Peptide-Directed Assembly of Single-Helical Gold Nanoparticle Superstructures Exhibiting Intense Chiroptical Activity. JACS, 138(41), 13655–63. 
  • Boatz et al. (2017) Cataract-associated P23T γD-crystallin retains a native-like fold in amorphous-looking aggregates formed at physiological pH. Nat Commun, 8, 15137. 

Location/Resources:

Our facility houses wide-bore 600MHz and 750MHz Bruker ssNMR spectrometers outfitted with 4-, 3.2-, 1.9-, and 1.3-mm CP/MAS as well as static ssNMR probes. Additional facilities include state-of-the-art EM, X-ray and solution NMR instrumentation, with the latter including 700, 800, and 900 MHz spectrometers. Excellent resources are available for protein production, biophysical and computational studies. The lab is housed in the interdisciplinary Dept of Structural Biology, one of the basic science departments of the University of Pittsburgh School of Medicine in Pittsburgh, Pennsylvania (USA). 

Application/More Information.

For more detailed information on these projects, links to related publications, and other information please visit the lab website at http://www.vanderwellab.org. To apply, or to obtain more information, please contact Patrick van der Wel by email at vanderwel@pitt.edu. Applications are expected to include a cover letter (or “cover email”) explaining specific research interests, a CV, and the names and contact information for three reference writers.

———————————–

====================================

This is the AMPERE MAGNETIC RESONANCE mailing list:

http://www.drorlist.com/nmrlist.html

NMR web database:

http://www.drorlist.com/nmr.html

[NMR] Postdoctoral position in structural biology of membrane remodeling

POSTDOCTORAL POSITION AVAILABLE

STRUCTURAL BIOLOGY OF MEMBRANE REMODELING

A NIH-funded postdoctoral position is available immediately in the Ramachandran Lab at Case Western Reserve University (CWRU) to study the structural aspects of protein-mediated membrane remodeling during endocytic and mitochondrial membrane fission. This position involves extensive collaboration with the lab of Patrick van der Wel at the University of Pittsburgh. The position requires a Ph.D. in biochemistry or biophysics with a focus on structural biology or membrane biophysics (NMR or ssNMR, preferably). This position will provide an excellent opportunity to learn and apply a wide array of structural and biophysical techniques to explore protein function on a model membrane surface. The Ramachandran laboratory also employs a host of cutting-edge spectroscopic approaches including FRET, fluorescence correlation spectroscopy (FCS) and fluorescence lifetime imaging (FLIM) to explore protein-protein and protein-membrane interactions in membrane remodeling and fission, both in vitro and in vivo. The Ramachandran and Van der Wel labs and the facilities at CWRU and University of Pittsburgh are equipped with state-of-the-art instrumentation for both biophysical techniques and structural biology, as well as for protein purification, characterization and membrane reconstitution.

Requirements: Applicants must be highly motivated and must have demonstrated experience (i.e. relevant publications) in protein biochemistry and structural biology. The candidate should have a strong conceptual and experimental background in biochemistry and biophysics, as well as in the mechanistic dissection of structure-function relationships in proteins; he/she should be independent, proactive, hardworking and productive; only candidates that have first-author publications (or articles in press) will be considered. Candidates must have completed their PhD at the time of appointment. Salary will commensurate with experience and will adhere to current NIH guidelines. Interested candidates should submit their CV, reprints of selected publications, three reference letters (directly from referees), and a cover letter summarizing their experience, long-term goals, and estimated start date directly to Rajesh Ramachandran at rxr275@case.edu.

Relevant Publications, please visit our webpage:

Ramachandran lab: https://physiology.case.edu/people/faculty/rajesh-ramachandran/

Van der Wel lab: http://www.vanderwellab.org

====================================

This is the AMPERE MAGNETIC RESONANCE mailing list:

http://www.drorlist.com/nmrlist.html

NMR web database:

http://www.drorlist.com/nmr.html

[NMR] ultra fast-MAS proton-detected solid-state NMR

PhD students and postdocs in ultra fast-MAS proton-detected solid-state NMR

The group of Prof. Dr. Rasmus Linser at the Ludwig-Maximilians-University in Munich, Germany, is looking for additional group members in the field of ultra fast-MAS bio-NMR.

Our focus is the characterization of protein structure, dynamics and interactions, using both solution and solid-state NMR spectroscopy. In the past, we have committed ourselves to the development of innovative NMR methodology as well as application of new and established methods to better understand the behavior of various proteins. In particular, we have a major record in proton-detected solid-state NMR, which is currently transforming into a new state of the art in solid-state NMR. Our interests nowadays are structure and dynamics playing a role for enzymatic function and for protein-small molecule interactions. Our lab has its own new 800 and 700 MHz magnets used for both, solids and solution. We own a broad selection of solids probes, including 3.2, 2.5, 1.3, and 0.7 mm, reaching up to the highest spin rates of commercially available technology above 110 kHz MAS. The biochemistry lab structure is very well set up (including for example a brand-new Beckman Coulter centrifuge and two ÄKTA systems) and furthermore well connected within the faculty.

The preferred candidate should be interested in both, protein preparation and NMR characterization of proteins, including all aspects from screening of conditions, assignments, structure calculation, and basics of dynamics.

He or she should be a devoted scientist hungry for structural biology data and scientific exchange with his or her fellow coworkers. A social and committed personality is also an important prerequisite.

Munich is a major science hub known for its lifestyle and culture, close to the Alps and picturesque nature reserves. The faculty for Chemistry and Pharmacy, including the Gene Center, is around the corner from the Biology campus and the MPI for biochemistry and has an extremely constructive and collegial vibe. The group forms part of several platforms fostering high-quality interdisciplinary research and scientific exchange, including the CIPSM Center of Excellence, the collaborative research project 749 the Center for NanoSciences CeNS, and the LMU Center for Advanced Studies.

Some German language skills would be desirable, but are not a must.

If you feel like you meet the above criteria, I would be very happy to get in touch.

Please also check the following webpages:

www.cup.lmu.de/oc/linser/

http://www.cipsm.de/

http://www.cens.de/

— 

Prof. Dr. Rasmus Linser

Ludwig-Maximilians-Universität München

Department Chemie

Butenandtstr. 5-13

81377 München

http://www.cup.lmu.de/oc/linser/

EMAIL: RASMUS.LINSER@LMU.DE

====================================

This is the AMPERE MAGNETIC RESONANCE mailing list:

http://www.drorlist.com/nmrlist.html

NMR web database:

http://www.drorlist.com/nmr.html

Have a question?

If you have questions about our instrumentation or how we can help you, please contact us.