Friday, September 30, 2016

Molecular Rationale for Improved Dynamic Nuclear Polarization of Biomembranes


Smith, A.N., et al., Molecular Rationale for Improved Dynamic Nuclear Polarization of Biomembranes. J Phys Chem B, 2016. 120(32): p. 7880-8.


Dynamic nuclear polarization (DNP) enhanced solid-state NMR can provide orders of magnitude in signal enhancement. One of the most important aspects of obtaining efficient DNP enhancements is the optimization of the paramagnetic polarization agents used. To date, the most utilized polarization agents are nitroxide biradicals. However, the efficiency of these polarization agents is diminished when used with samples other than small molecule model compounds. We recently demonstrated the effectiveness of nitroxide labeled lipids as polarization agents for lipids and a membrane embedded peptide. Here, we systematically characterize, via electron paramagnetic (EPR), the dynamics of and the dipolar couplings between nitroxide labeled lipids under conditions relevant to DNP applications. Complemented by DNP enhanced solid-state NMR measurements at 600 MHz/395 GHz, a molecular rationale for the efficiency of nitroxide labeled lipids as DNP polarization agents is developed. Specifically, optimal DNP enhancements are obtained when the nitroxide moiety is attached to the lipid choline headgroup and local nitroxide concentrations yield an average e(-)-e(-) dipolar coupling of 47 MHz. On the basis of these measurements, we propose a framework for development of DNP polarization agents optimal for membrane protein structure determination.

Thursday, September 29, 2016

Two Research Fellow positions and one PhD studentship at University of Southampton #DNPNMR

From the Ampere Magnetic Resonance List



Dear Colleagues,

I have two open Reserach Fellow Positions and a fully funded PhD studentship in my group (http://www.southampton.ac.uk/chemistry/about/staff/pileio.page) at the University of Southampton.

* Post-Doctoral Research Fellowship in nuclear magnetic resonance in the research group of Dr Giuseppe Pileio, in collaboration with Prof Malcolm H Levitt. The project, funded by EPSRC(UK), concerns the development of NMR hardware and methodology that combines supercritical fluids with long-lived states NMR and dissolution-DNP to prolong the storage of hyperpolarised spin order and allow it to be transported remotely from the production site. The position is tenable from 1 December 2016 or as soon as possible thereafter with initial appointment for 2 years but with the possibility of a further extension of 1 more years, subject to project requirements. For further details and how to apply please follow this link: https://jobs.soton.ac.uk/Vacancy.aspx?id=14426&forced=1

* A 3 years PhD studentship is also available on the same project with application deadline 31 October 2016 and a salary of £14,296 per annum. For further details and how to apply please follow this link: https://jobs.soton.ac.uk/Vacancy.aspx?ref=782416EB . Please note that: due to funding restrictions this position is only open to UK/EU applicants

* Post-Doctoral Research Fellowship in nuclear magnetic resonance in the research group of Dr Giuseppe Pileio. The project, funded by EPSRC under the First Grant scheme, concerns the development of NMR methodology to probe translational dynamics in porous media by singlet-state NMR spectroscopy. The position is tenable from 1 November 2016 or as soon as possible thereafter with appointment for 1 year but with the possibility of a further extension of 1 more year, subject to funding and project requirements. For further details and how to apply please follow this link: https://jobs.soton.ac.uk/Vacancy.aspx?id=14420&forced=1

University of Southampton is a UK Russell Group university positioned in the top 1% of world universities according to QS World University Rankings. We have an international reputation for research, teaching and enterprise activities. Southampton is particularly well known for its magnetic resonance and computational chemistry research.

Many Thanks,
Dr. Giuseppe Pileio, PhD

Lecturer in Physical Chemistry,
Department of Chemistry,
Building 27 - Room 2059,
University of Southampton,
University Road, SO17 1BJ,
Internal Post Code: M16,
Southampton, Hampshire, UK.

Tel.: +44 (023) 80 59 4160
ORCID: 0000-0001-9223-3896

====================================
This is the AMPERE MAGNETIC RESONANCE mailing list:

NMR web database:

Wednesday, September 28, 2016

Filterable Agents for Hyperpolarization of Water, Metabolites, and Proteins


Vuichoud, B., et al., Filterable Agents for Hyperpolarization of Water, Metabolites, and Proteins. Chemistry, 2016: p. n/a-n/a.


Hyperpolarization is generated by dissolution dynamic nuclear polarization (d-DNP) using a polymer-based polarizing agent dubbed FLAP (filterable labeled agents for polarization). It consists of a thermo-responsive poly(N-isopropylacrylamide), also known as pNiPAM-COOH, labeled with nitroxide radicals. The polymer powder is impregnated with an arbitrary solution of interest and frozen as is. Dissolution is followed by a simple filtration, leading to hyperpolarized solutions free from any contaminants. We demonstrated the use of FLAP to hyperpolarize partially deuterated water up to P(1 H)=6 % with a long relaxation T1 >36 s characteristic of high purity. Water hyperpolarization can be transferred to drugs, metabolites, or proteins that are waiting in an NMR spectrometer, either by exchange of labile protons or through intermolecular Overhauser effects. We also show that FLAPs are suitable polarizing agents for 13 C-labeled metabolites such as pyruvate, acetate, and alanine.

Tuesday, September 27, 2016

IVAN (International Varian-Agilent NMR users group) Introduction

Introduction of IVAN


The International Varian-Agilent NMR users group sponsored by MR Resources.

MR Resources is pleased to announce the formation of a new international organization directed toward owners and users of NMR spectrometers from Varian Inc. and Agilent Technologies Inc.

As we all know, on October 14, 2014 Agilent Technologies Inc., owner of the former NMR division of Varian Inc., exited the NMR business. As a result, during the two years since, MR Resources has greatly increased its service and support commitment to Varian-Agilent NMR owners and users, welcoming many new customers in the process. MR Resources is fully dedicated to helping support the approximately 5,500 Varian-Agilent NMR spectrometers that remain in use worldwide. We hope that MR Resources will be the new home for all Varian-Agilent NMR spectrometer owners and users worldwide.

As such, to further increase our on-going commitment to Varian-Agilent NMR users, MR Resources will provide full and exclusive sponsorship for the IVAN Users Group. The purpose of the group will be to facilitate on-going technical support of the International Varian-Agilent NMR spectrometer user community by fostering interactive information exchange and face-to-face meetings of users. We wish to provide a much needed home base and platform for meetings, communications and other activities for owners and users of Varian-Agilent NMR spectrometers. MR Resources and IVAN are not affiliated with Agilent Technologies Inc. or Varian Inc. in any way.

The IVAN Users Group is now officially active, and to start things off MR Resources will sponsor a series of informative and interactive meetings for Varian-Agilent NMR users locally, regionally and in conjunction with NMR conferences. The IVAN meetings will take place in different locations around the world. Locations for meetings will be determined by the needs of users. Please indicate on the membership sign-up form if you would like to participate in an organization in your area. These meetings will be exclusive to IVAN User Group members and will be free of charge to attend. These meetings will bring together owners, customers and users, along with MR Resources personnel and many highly committed former Varian-Agilent experts. Indeed, the IVAN Executive Committee is comprised of a "Who's Who" from the Varian-Agilent NMR companies and the NMR community at large. Our first meeting will be in San Jose, California at the Fairmont Hotel on Friday October 28, 2016. We are also planning a subsequent full day meeting to accompany the Asilomar ENC in the spring of 2017 to be held the Saturday before the ENC opening.

If you are an owner of a Varian-Agilent NMR spectrometer or an interested user, you are invited to join IVAN and attend our meetings, as well as participate in other activities that will soon be developed. Select Join IVAN and fill out the membership form. We urge as many Varian-Agilent NMR spectrometer owners and users worldwide to join this very important group in order to ensure continuing operation and longevity of the Varian-Agilent NMR systems that we all have such a huge investment in.

Membership

Membership in IVAN is available to all Varian-Agilent NMR spectrometer owners and interested users, independent of your service plan or status as a MR Resources customer. There is no charge to become a member or to participate in meetings and activities. There are some restrictions on membership for those who do not identify as a direct Varian-Agilent NMR end-user site and for those that are NMR Vendors. MR Resources intends its own commercial involvement in the user group to be low key. The success of the IVAN user group depends upon the activities of its members. The role of MR Resources is to provide a home for meetings and communication. An email link is available on the membership form to contact us directly with questions about membership.

The on-going objectives for IVAN will be those of its users to enhance the usefulness of their NMR systems, extend the lifetime of the instruments, and to keep them running properly.

First IVAN Meeting, Fall 2016

We invite you to attend a kick-off meeting for IVAN in the San Francisco Bay Area on Friday October 28, 2016. The meeting will be one day – 10:00 AM to 3:30 PM at the Fairmont Hotel in San Jose, including lunch and followed by a "Happy Hour" at the Fairmont. Once you join IVAN you may select Our First Meeting in San Jose to register for the upcoming user meeting.

We have a large conference room and catering arranged for up to 100 individuals. Space is limited so sign up early! We hope to see many of you from the Bay Area and we make a special invitation to users from the US West Coast and further distances as well. We promise that you will not be disappointed and hope you can make it if possible! If not, a meeting the day before ENC in Monterey, California is in planning, and other local meetings are already under discussion.

Agenda for the Founding San Jose IVAN Meeting
  9:00 AM:  
Registration and Coffee at the Fairmont
10:00 AM:
Welcome and Introduction of Jon Webb (Dave Rice)
10:10 AM:
A Vision for the Future for Varian-Agilent NMR  (Jon Webb, MR Resources)
10:45 AM: 
Announcing OpenVnmrJ1 Software for the Varian-Agilent Community (Dan Iverson)
11:30 AM:
Discussion Topic:
Moving Forward Together with Service and Applications2 (chair: Michele Bodner)
12:00 PM:
Lunch will be served during the discussion.
1:15 PM 
Operation/Applications Sessions3 (organizers: Krish Krishnamurthy and Dave Russell)
3:00-3:30 PM
Conclusions and Planning for the Future
4:00 PM …. 
 “Happy Hour” (Soda, Wine and Beer Catered)

1OpenVnmrJ1.1A is an open-source successor to Agilent's VnmrJ4.2A, released by VOSSG, the VnmrJ Open-Source Steering Committee on 12-Sept-2016. VOSSG will continue development of OpenVnmrJ in association with the IVAN group.
2 A discussion of how we users can enhance the longevity and productivity of our Varian-Agilent consoles, probes and magnets. Bring your questions and issues.
3 We anticipate special topics chosen from the list below. Check the website www.mrr.com for potential topics.

Meeting Special Topics

The topics below are under consideration for the afternoon sessions. Feel free to give your feedback about the choices with the following email link. We will select a subset, but at the very least, experts in these topics will be present at the San Jose meeting. Come with your questions!
  • New Veripulse Calibration with OpenVnmrJ (and VnmrJ4.2)
  • Software Administration and Automation with OpenVnmrJ (and VnmrJ4.2)
  • New 1D and 2D CRAFT from Chempacker
  • Using Chempack Tools
  • Biopack, NUS and NMRPipe with OpenVnmrJ (and VnmrJ4.2)
  • Managing Solids and Programming with SolidsPack Tools.
You can register for IVAN at the MRR webiste here. IVAN Registration
If you have more questions about IVAN you can send us an e-mail thru our website here. IVAN Questions


This email was sent to tmaly@bridge12.com 
MR Resources · 160 Authority Drive · Fitchburg, MA 01420 · USA 


Monday, September 26, 2016

Milli-tesla NMR and spectrophotometry of liquids hyperpolarized by dissolution dynamic nuclear polarization


Zhu, Y., et al., Milli-tesla NMR and spectrophotometry of liquids hyperpolarized by dissolution dynamic nuclear polarization. J Magn Reson, 2016. 270: p. 71-6.


Hyperpolarization methods offer a unique means of improving low signal strength obtained in low-field NMR. Here, simultaneous measurements of NMR at a field of 0.7mT and laser optical absorption from samples hyperpolarized by dissolution dynamic nuclear polarization (D-DNP) are reported. The NMR measurement field closely corresponds to a typical field encountered during sample injection in a D-DNP experiment. The optical spectroscopy allows determination of the concentration of the free radical required for DNP. Correlation of radical concentration to NMR measurement of spin polarization and spin-lattice relaxation time allows determination of relaxivity and can be used for optimization of the D-DNP process. Further, the observation of the nuclear Overhauser effect originating from hyperpolarized spins is demonstrated. Signals from (1)H and (19)F in a mixture of trifluoroethanol and water are detected in a single spectrum, while different atoms of the same type are distinguished by J-coupling patterns. The resulting signal changes of individual peaks are indicative of molecular contact, suggesting a new application area of hyperpolarized low-field NMR for the determination of intermolecular interactions.

Friday, September 23, 2016

Hydration Dynamics of a Peripheral Membrane Protein #DNPNMR


Fisette, O., et al., Hydration Dynamics of a Peripheral Membrane Protein. J. Am. Chem. Soc., 2016. 138(36): p. 11526-11535.


Water dynamics in the hydration shell of the peripheral membrane protein annexin B12 were studied using MD simulations and Overhauser DNP-enhanced NMR. We show that retardation of water motions near phospholipid bilayers is extended by the presence of a membrane-bound protein, up to around 10 Å above that protein. Near the membrane surface, electrostatic interactions with the lipid head groups strongly slow down water dynamics, whereas protein-induced water retardation is weaker and dominates only at distances beyond 10 Å from the membrane surface. The results can be understood from a simple model based on additive contributions from the membrane and the protein to the activation free energy barriers of water diffusion next to the biomolecular surfaces. Furthermore, analysis of the intermolecular vibrations of the water network reveals that retarded water motions near the membrane shift the vibrational modes to higher frequencies, which we used to identify an entropy gradient from the membrane surface toward the bulk water. Our results have implications for processes that take place at lipid membrane surfaces, including molecular recognition, binding, and protein–protein interactions.

Wednesday, September 21, 2016

Impact of Ho3+-doping on 13C dynamic nuclear polarization using trityl OX063 free radical #DNPNMR


Kiswandhi, A., et al., Impact of Ho3+-doping on 13C dynamic nuclear polarization using trityl OX063 free radical. Phys. Chem. Chem. Phys., 2016. 18(31): p. 21351-21359.


We have investigated the effects of Ho-DOTA doping on the dynamic nuclear polarization (DNP) of [1-13C] sodium acetate using trityl OX063 free radical at 3.35 T and 1.2 K. Our results indicate that addition of 2 mM Ho-DOTA on 3 M [1-13C] sodium acetate sample in 1 : 1 v/v glycerol : water with 15 mM trityl OX063 improves the DNP-enhanced 13C solid-state nuclear polarization by a factor of around 2.7-fold. Similar to the Gd3+ doping effect on 13C DNP, the locations of the positive and negative 13C maximum polarization peaks in the 13C microwave DNP sweep are shifted towards each other with the addition of Ho-DOTA on the DNP sample. W-band electron spin resonance (ESR) studies have revealed that while the shape and linewidth of the trityl OX063 ESR spectrum was not affected by Ho3+-doping, the electron spin-lattice relaxation time T1 of trityl OX063 was prominently reduced at cryogenic temperatures. The reduction of trityl OX063 electron T1 by Ho-doping is linked to the 13C DNP improvement in light of the thermodynamic picture of DNP. Moreover, the presence of Ho-DOTA in the dissolution liquid at room temperature has negligible reduction effect on liquid-state 13C T1, in contrast to Gd3+-doping which drastically reduces the 13C T1. The results here suggest that Ho3+-doping is advantageous over Gd3+ in terms of preservation of hyperpolarized state-an important aspect to consider for in vitro and in vivo NMR or imaging (MRI) experiments where a considerable preparation time is needed to administer the hyperpolarized 13C liquid.

Friday, September 16, 2016

Heteronuclear DNP of protons and deuterons with TEMPOL #DNPNMR


Kaminker, I., et al., Heteronuclear DNP of protons and deuterons with TEMPOL. Phys Chem Chem Phys, 2016. 18(16): p. 11017-41.


Dynamic nuclear polarization (DNP) experiments on samples with several types of magnetic nuclei sometimes exhibit "cross-talk" between the nuclei, such as different nuclei having DNP spectra with similar shapes and enhancements. In this work we demonstrate that while at 20 K the DNP spectra of (1)H and (2)H nuclei, in a sample composed of 50% v/v (1)H2O/DMSO-d6 and containing 40 mM TEMPOL, are different and can be analyzed using the indirect cross effect (iCE) model, at 6 K the DNP spectra of both (1)H and (2)H nuclei become identical. In addition we experimentally demonstrate that there exists an efficient polarization exchange between the two nuclear pools at this temperature. Both of these results are hallmark predictions of the thermal mixing (TM) formalism. However, the origin of these observations cannot, in our case, be explained using the standard TM formalism, as in our sample the electron reservoir cannot be described by a single non-Zeeman spin temperature, which is a prerequisite of TM. This conclusion follows from the analysis of the electron electron double resonance (ELDOR) experiments on our sample and is similar to the previously published results. Consequently, another mechanism must be used in order to explain these "cross-talk" effects. The heteronuclear cross effect (hnCE) DNP mechanism, previously introduced based on the simulations of the spin evolution in small model systems, results in "cross-talk" effects between two types of nuclei that are similar to the experimental ones seen in this work. In particular we show that the hnCE mechanism exhibits polarization transfer between the nuclei and that there exists a clear relationship between the steady state polarizations of the two types of nuclei which may, in the future, be correlated with the phenomenon observed in the two types of bulk nuclear signals in samples during DNP experiments. It is suggested that the hnCE electrons are a possible source for the process that equalizes the bulk enhancements of the (1)H and (2)H nuclei and are responsible for the observed cross-talk effects.

Wednesday, September 14, 2016

Room-temperature electron spin relaxation of nitroxides immobilized in trehalose: Effect of substituents adjacent to NO-group


Kuzhelev, A.A., et al., Room-temperature electron spin relaxation of nitroxides immobilized in trehalose: Effect of substituents adjacent to NO-group. J. Magn. Reson., 2016. 266: p. 1-7.


Trehalose has been recently promoted as efficient immobilizer of biomolecules for room-temperature EPR studies, including distance measurements between attached nitroxide spin labels. Generally, the structure of nitroxide influences the electron spin relaxation times, being crucial parameters for room-temperature pulse EPR measurements. Therefore, in this work we investigated a series of nitroxides with different substituents adjacent to NO-moiety including spirocyclohexane, spirocyclopentane, tetraethyl and tetramethyl groups. Electron spin relaxation times (T1, Tm) of these radicals immobilized in trehalose were measured at room temperature at X- and Q-bands (9/34 GHz). In addition, a comparison was made with the corresponding relaxation times in nitroxide-labeled DNA immobilized in trehalose. In all cases phase memory times Tm were close to 700 ns and did not essentially depend on structure of substituents. Comparison of temperature dependences of Tm at T = 80–300 K shows that the benefit of spirocyclohexane substituents well-known at medium temperatures (∼100–180 K) becomes negligible at 300 K. Therefore, unless there are specific interactions between spin labels and biomolecules, the room-temperature value of Tm in trehalose is weakly dependent on the structure of substituents adjacent to NO-moiety of nitroxide. The issues of specific interactions and stability of nitroxide labels in biological media might be more important for room temperature pulsed dipolar EPR than differences in intrinsic spin relaxation of radicals.

Tuesday, September 13, 2016

[NMR] Post-doctoral position in MAS-DNP at Aix-Marseille University (France) #DNPNMR

From the Ampere Magnetic Resonance List

A one-year post-doctoral position is available at the solid-state NMR group of Aix-Marseille University. The goal of the project is to investigate molecular crystals and powders, which cannot be characterized with conventional techniques, using solid-state NMR and dynamic nuclear polarization (DNP). The research work will be based on the preliminary results published in Angew. Chem. Int. Ed. Vol.54 p.6028 (dx.doi.org/10.1002/anie.201501172)

The net salary is around 2000€/month (Healthcare included) according to the experience of the candidate. 

The position is available immediately, and interested candidates should send their CV's including the name of at least one reference to Pierre Thureau pierre.thureau@univ-amu.fr

====================================
This is the AMPERE MAGNETIC RESONANCE mailing list:

NMR web database:

Monday, September 12, 2016

Hyperpolarization of Frozen Hydrocarbon Gases by Dynamic Nuclear Polarization at 1.2 K #DNPNMR


Vuichoud, B., et al., Hyperpolarization of Frozen Hydrocarbon Gases by Dynamic Nuclear Polarization at 1.2 K. J Phys Chem Lett, 2016. 7(16): p. 3235-9.


We report a simple and general method for the hyperpolarization of condensed gases by dynamic nuclear polarization (DNP). The gases are adsorbed in the pores of structured mesoporous silica matrices known as HYPSOs (HYper Polarizing SOlids) that have paramagnetic polarizing agents covalently bound to the surface of the mesopores. DNP is performed at low temperatures and moderate magnetic fields (T = 1.2 K and B0 = 6.7 T). Frequency-modulated microwave irradiation is applied close to the electron spin resonance frequency (f = 188.3 GHz), and the electron spin polarization of the polarizing agents of HYPSO is transferred to the nuclear spins of the frozen gas. A proton polarization as high as P((1)H) = 70% can be obtained, which can be subsequently transferred to (13)C in natural abundance by cross-polarization, yielding up to P((13)C) = 27% for ethylene.

Friday, September 9, 2016

[NMR] Postdoctoral Position in Biomolecular Solid-State NMR at USC, Los Angeles

From the Ampere Magnetic Resonance List


The Siemer lab at USC is looking for a postdoctoral associate with a background in NMR spectroscopy and knowledge of protein biochemical techniques. The lab studies the structure and dynamics of functional and toxic amyloid fibrils. To this goal we apply solid-state NMR spectroscopy in conjunction with other biochemical and biophysical methods.

The Siemer lab is part of the Protein Structure Center at USC and works in close collaboration wit the EPR lab of Ralf Langen and liquid-state NMR lab of Tobias Ulmer as part of an effort to investigate nervous system function with biophysical methods in an interdisciplinary environment.

The position is available immediately, and interested candidates should send their CV's including the names of three references to Ansgar Siemer asiemer@usc.edu.

-- 
Ansgar B Siemer 
Assistant Professor,
Biochemistry & Molecular Biology
Zilkha Neurogenetic Institute
Keck School of Medicine of USC
1501 San Pablo Street, ZNI 119F
Los Angeles, CA 90033
Tel: +1-323-442-2720

====================================
This is the AMPERE MAGNETIC RESONANCE mailing list:

NMR web database:

Structural analysis of a signal peptide inside the ribosome tunnel by DNP MAS NMR #DNPNMR


Lange, S., et al., Structural analysis of a signal peptide inside the ribosome tunnel by DNP MAS NMR. Sci Adv, 2016. 2(8): p. e1600379.


Proteins are synthesized in cells by ribosomes and, in parallel, prepared for folding or targeting. While ribosomal protein synthesis is progressing, the nascent chain exposes amino-terminal signal sequences or transmembrane domains that mediate interactions with specific interaction partners, such as the signal recognition particle (SRP), the SecA-adenosine triphosphatase, or the trigger factor. These binding events can set the course for folding in the cytoplasm and translocation across or insertion into membranes. A distinction of the respective pathways depends largely on the hydrophobicity of the recognition sequence. Hydrophobic transmembrane domains stabilize SRP binding, whereas less hydrophobic signal sequences, typical for periplasmic and outer membrane proteins, stimulate SecA binding and disfavor SRP interactions. In this context, the formation of helical structures of signal peptides within the ribosome was considered to be an important factor. We applied dynamic nuclear polarization magic-angle spinning nuclear magnetic resonance to investigate the conformational states of the disulfide oxidoreductase A (DsbA) signal peptide stalled within the exit tunnel of the ribosome. Our results suggest that the nascent chain comprising the DsbA signal sequence adopts an extended structure in the ribosome with only minor populations of helical structure.

Wednesday, September 7, 2016

Molecular Rationale for Improved Dynamic Nuclear Polarization of Biomembranes #DNPNMR


Smith, A.N., et al., Molecular Rationale for Improved Dynamic Nuclear Polarization of Biomembranes. J Phys Chem B, 2016. 120(32): p. 7880-8.


Dynamic nuclear polarization (DNP) enhanced solid-state NMR can provide orders of magnitude in signal enhancement. One of the most important aspects of obtaining efficient DNP enhancements is the optimization of the paramagnetic polarization agents used. To date, the most utilized polarization agents are nitroxide biradicals. However, the efficiency of these polarization agents is diminished when used with samples other than small molecule model compounds. We recently demonstrated the effectiveness of nitroxide labeled lipids as polarization agents for lipids and a membrane embedded peptide. Here, we systematically characterize, via electron paramagnetic (EPR), the dynamics of and the dipolar couplings between nitroxide labeled lipids under conditions relevant to DNP applications. Complemented by DNP enhanced solid-state NMR measurements at 600 MHz/395 GHz, a molecular rationale for the efficiency of nitroxide labeled lipids as DNP polarization agents is developed. Specifically, optimal DNP enhancements are obtained when the nitroxide moiety is attached to the lipid choline headgroup and local nitroxide concentrations yield an average e(-)-e(-) dipolar coupling of 47 MHz. On the basis of these measurements, we propose a framework for development of DNP polarization agents optimal for membrane protein structure determination.

Friday, September 2, 2016

500-fold enhancement of in situ (13)C liquid state NMR using gyrotron-driven temperature-jump DNP #DNPNMR


Yoon, D., et al., 500-fold enhancement of in situ (13)C liquid state NMR using gyrotron-driven temperature-jump DNP. J Magn Reson, 2016. 270: p. 142-6.


A 550-fold increase in the liquid state (13)C NMR signal of a 50muL sample was obtained by first hyperpolarizing the sample at 20K using a gyrotron (260GHz), then, switching its frequency in order to apply 100W for 1.5s so as to melt the sample, finally, turning off the gyrotron to acquire the (13)C NMR signal. The sample stays in its NMR resonator, so the sequence can be repeated with rapid cooling as the entire cryostat stays cold. DNP and thawing of the sample are performed only by the switchable and tunable gyrotron without external devices. Rapid transition from DNP to thawing in one second time scale was necessary especially in order to enhance liquid (1)H NMR signal.

Thursday, September 1, 2016

[NMR] Post-doctoral position in MAS-DNP, Lyon, France #DNPNMR

From the Ampere Magnetic Resonance List



A post-doctoral position is available in MAS-DNP at the High-Field NMR Center of Lyon (France)

Contact: Anne Lesage (anne.lesage@ens-lyon.fr)

The project will be developed at the Center for Very High Field NMR in Lyon, a research unit of the Institute of Analytical Sciences, affiliated with the CNRS, the UCBL and the ENS de Lyon.

The project will focus on the development of new strategies for high-field DNP enhanced solid-state NMR spectroscopy. It will include i) the implementation of new NMR methods tailored for high-field and fast MAS DNP, ii) the development of a novel generation of polarizing agents and iii) the application of these approaches to the investigation of challenging systems in materials science and structural biology.

Working environment: The High-Field NMR center of Lyon hosts two DNP systems operating at 400 MHz WB / 263 GHz and 800 MHz WB / 527 GHz. Both instruments are equipped with 3.2 and 1.3 mm DNP probes. In addition the center hosts 4 other NMR spectrometers (500 MHz WB, 700 MHz, 800 MH and 1000 MHz), all equipped with state-of-the-art solid-state NMR hardware. The NMR research groups of the CRMN are of worldwide-recognized excellence, notably in the field of solid-state NMR of materials and proteins, as well as in the field of hyperpolarisation techniques. The project will be carried out in an international environment, using a unique equipment worldwide, and in collaboration with leading groups in NMR spectroscopy and in radical design.

If you are interested, please send your application (a detailed CV and a motivation letter) to: anne.lesage@ens-lyon.fr

====================================
This is the AMPERE MAGNETIC RESONANCE mailing list:

NMR web database: