Wednesday, May 31, 2017

Fast and accurate MAS-DNP simulations of large spin ensembles #DNPNMR


Mentink-Vigier, F., S. Vega, and G. De Paepe, Fast and accurate MAS-DNP simulations of large spin ensembles. Phys. Chem. Chem. Phys., 2017. 19(5): p. 3506-3522.


A deeper understanding of parameters affecting Magic Angle Spinning Dynamic Nuclear Polarization (MAS-DNP), an emerging nuclear magnetic resonance hyperpolarization method, is crucial for the development of new polarizing agents and the successful implementation of the technique at higher magnetic fields (>10 T). Such progress is currently impeded by computational limitation which prevents the simulation of large spin ensembles (electron as well as nuclear spins) and to accurately describe the interplay between all the multiple key parameters at play. In this work, we present an alternative approach to existing cross-effect and solid-effect MAS-DNP codes that yields fast and accurate simulations. More specifically we describe the model, the associated Liouville-based formalism (Bloch-type derivation and/or Landau-Zener approximations) and the linear time algorithm that allows computing MAS-DNP mechanisms with unprecedented time savings. As a result, one can easily scan through multiple parameters and disentangle their mutual influences. In addition, the simulation code is able to handle multiple electrons and protons, which allows probing the effect of (hyper)polarizing agents concentration, as well as fully revealing the interplay between the polarizing agent structure and the hyperfine couplings, nuclear dipolar couplings, nuclear relaxation times, both in terms of depolarization effect, but also of polarization gain and buildup times.

Friday, May 26, 2017

Nuclear-Electron Overhauser Effect in MC800 Liquid Asphalt Solutions


Yet another application (although not new) for Overhauser DNP at 9 GHz. 





Firat, Y.E., H. Yildirim, and A. Peksoz, Nuclear-Electron Overhauser Effect in MC800 Liquid Asphalt Solutions. Journal of Dispersion Science and Technology, 2015. 37(9): p. 1349-1359.


Experimental results on the extrapolated ultimate enhancement factors of o-, m-, and p-xylene protons at 1.53 mT are obtained for MC800 asphalt solutions. The ultimate enhancement factors are found such as ?26.9, ?25.7, and ?11.7 for o-, m-, and p-xylene, respectively. These results show that the solvent proton Overhauser effect cannot reach the extrapolated enhancement of ?330 in the extreme narrowing case because of occurrence of small scalar interactions in addition to the dipole?dipole interactions between solvent protons and asphalt electrons. The ortho, meta, and para positions of the ?CH3 group change the nature of the interactions. The nuclear magnetic resonance (NMR) signal enhancements exhibit a sensitive behavior depending on the chemical environment differing from isomer to isomer. The solvation or association of asphalt in xylene isomers at room temperature is revealed. Quantum chemical calculations for the xylene isomers with the electronic and optical properties; absorption wavelengths, excitation energy, atomic charges, dipole moment and frontier molecular orbital energies, molecular electrostatic potential; are carried out using the density functional theory (DFT) method (B3LYP) with the 6-311G(d,p) basis set by the standard Gaussian 09 software package program. The relative importance of scalar and translational dipolar interaction parameters determined in dynamic nuclear polarization experiments is explained by the electronic structure of HOMO?LUMO of the xylene isomers.

Wednesday, May 24, 2017

High field hyperpolarization-EXSY experiment for fast determination of dissociation rates in SABRE complexes


Hermkens, N.K.J., et al., High field hyperpolarization-EXSY experiment for fast determination of dissociation rates in SABRE complexes. J. Magn. Reson., 2017. 276: p. 122-127.


SABRE (Signal Amplification By Reversible Exchange) is a nuclear spin hyperpolarization technique based on the reversible concurrent binding of small molecules and para-hydrogen (p-H2) to an iridium metal complex in solution. At low magnetic field, spontaneous conversion of p-H2 spin order to enhanced longitudinal magnetization of the nuclear spins of the other ligands occurs. Subsequent complex dissociation results in hyperpolarized substrate molecules in solution. The lifetime of this complex plays a crucial role in attained SABRE NMR signal enhancements. Depending on the ligands, vastly different dissociation rates have been previously measured using EXSY or selective inversion experiments. However, both these approaches are generally time-consuming due to the long recycle delays (up to 2 min) necessary to reach thermal equilibrium for the nuclear spins of interest. In the cases of dilute solutions, signal averaging aggravates the problem, further extending the experimental time. Here, a new approach is proposed based on coherent hyperpolarization transfer to substrate protons in asymmetric complexes at high magnetic field. We have previously shown that such asymmetric complexes are important for application of SABRE to dilute substrates. Our results demonstrate that a series of high sensitivity EXSY spectra can be collected in a short experimental time thanks to the NMR signal enhancement and much shorter recycle delay.

Monday, May 22, 2017

Molecular dynamics-based selectivity for Fast-Field-Cycling relaxometry by Overhauser and solid effect dynamic nuclear polarization #DNPNMR


Neudert, O., C. Mattea, and S. Stapf, Molecular dynamics-based selectivity for Fast-Field-Cycling relaxometry by Overhauser and solid effect dynamic nuclear polarization. J. Magn. Reson., 2017. 276: p. 113-121.


In the last decade nuclear spin hyperpolarization methods, especially Dynamic Nuclear Polarization (DNP), have provided unprecedented possibilities for various NMR techniques by increasing the sensitivity by several orders of magnitude. Recently, in-situ DNP-enhanced Fast Field Cycling (FFC) relaxometry was shown to provide appreciable NMR signal enhancements in liquids and viscous systems. In this work, a measurement protocol for DNP-enhanced NMR studies is introduced which enables the selective detection of nuclear spin hyperpolarized by either Overhauser effect or solid effect DNP. Based on field-cycled DNP and relaxation studies it is shown that these methods allow for the independent measurement of polymer and solvent nuclear spins in a concentrated solution of high molecular weight polybutadiene in benzene doped with α,γ-bisdiphenylene-β-phenylallyl radical. Appreciable NMR signal enhancements of about 10-fold were obtained for both constituents. Moreover, qualitative information about the dynamics of the radical and solvent was obtained. Selective DNP-enhanced FFC relaxometry is applied for the measurement of the 1H nuclear magnetic relaxation dispersion of both constituents with improved precision. The introduced method is expected to greatly facilitate NMR studies of complex systems with multiple overlapping signal contributions that cannot be distinguished by standard methods.

Friday, May 19, 2017

T1 - Dynamic Nuclear Polarization Signal Enhancement with High-Affinity Biradical Tags #DNPNMR

Rivkah Rogawski, Ivan V. Sergeyev, Yongjun Li, M. Francesca Ottaviani, Virginia Cornish, and Ann E. McDermott The Journal of Physical Chemistry B 2017 121 (6), 1169-1175


Dynamic nuclear polarization is an emerging technique for sensitizing solid-state NMR experiments by transferring polarization from electrons to nuclei. Stable biradicals, the polarization source for the cross effect mechanism, are typically codissolved at millimolar concentrations with proteins of interest. Here we describe the high-affinity biradical tag TMP-T, created by covalently linking trimethoprim, a nanomolar affinity ligand of dihydrofolate reductase (DHFR), to the biradical polarizing agent TOTAPOL. With TMP-T bound to DHFR, large enhancements of the protein spectrum are observed, comparable to when TOTAPOL is codissolved with the protein. In contrast to TOTAPOL, the tight binding TMP-T can be added stoichiometrically at radical concentrations orders of magnitude lower than in previously described preparations. Benefits of the reduced radical concentration include reduced spectral bleaching, reduced chemical perturbation of the sample, and the ability to selectively enhance signals for the protein of interest.

Thursday, May 18, 2017

[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:

NMR web database:

[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:

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

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

NMR web database:

[NMR] Position as Research Engineer / Lab Manager for the magnetic resonance lab @ IPF Dresden


Position as Research Engineer / Lab Manager for the magnetic resonance lab @ IPF Dresden

At the Institute of Physical Chemistry and Polymer Physics, Department Polyelectrolytes and Dispersions, at the 

Leibniz-Institut für Polymerforschung is an opening for a Research Engineer / Lab Manager for the magnetic resonance laboratory. 

We are looking for a motivated, skillful person, who is willing to learn about novel technolgies and is closely collaborating with the PI's. The research engineer will be responsible for ensuring the operation of the laboratory and the various spectrometers (high-field NMR, low-field NMR and X-band EPR), perform routine experiments and sample preparation and support in simulations. Ensuring the smooth operation of the lab includes trouble shooting and modification of experimental setups. Skills in electronics and computing are desirable.

Qualification: MSc/Diploma in Physical Technology or equivalent
Duration: initially for two years

The Leibniz-Institut für Polymerforschung Dresden e.V. (IPF) is one of the largest polymer research facilities in Germany. As an institute of the Leibniz Association, the IPF is committed to carrying out application-oriented basic research. The focus of activities at the IPF is directed toward the advancement of basic scientific knowledge for the development of functional polymer materials and polymer materials with new or improved characteristics. Leading scientists of the IPF are at the same time appointed professors at the Technische Universität Dresden (TUD). Since 2011 the TUD has been one of the excellence universities in Germany. The IPF offers a stimulating working atmosphere for outstanding interdisciplinary research in one of the most beautiful cities of Germany. 

Dresden, the capital of Saxony, possesses an extraordinarily high density of research facilities which have made Dresden a leading research site, particularly in the fields of material research, microelectronics, and biotechnology. 

Applications including motivation letter, CV, should be submitted by e-mail as a single PDF document to the Department of Human Resources (with the No. 063-2017):

Leibniz-Institut für Polymerforschung Dresden e.V.
Frau Susanne Otto
Leiterin Personal und Soziales
Hohe Straße 6
01069 Dresden

Queries about the lab and the research project should be directed by e-mail to:
Ulrich Scheler Scheler@ipfdd.de .

Job offer (in German)

Best regards,
Ulrich Scheler

-------------------------------------------------------------
Dr. Ulrich Scheler
Leibniz-Institut für Polymerforschung Dresden e.V.
Hohe Strasse 6
D-01069 Dresden, Germany
phone +49 351 4658 275
fax +49 351 4658 231
--------------------------------------------------------------


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

NMR web database:

Wednesday, May 17, 2017

Surface-selective direct 17O DNP NMR of CeO2 nanoparticles #DNPNMR

Michael A. Hope et. al, Chem. Commun., 2017,53, 2142-2145 


Surface-selective direct 17O DNP has been demonstrated for the first time on CeO2nanoparticles, for which the first three layers can be distinguished with high selectivity. Polarisation build-up curves show that the polarisation of the (sub-)surface sites builds up faster than the bulk, accounting for the remarkable surface selectivity.

Monday, May 15, 2017

Site specific polarization transfer from a hyperpolarized ligand of dihydrofolate reductase


Wang, Y., M. Ragavan, and C. Hilty, Site specific polarization transfer from a hyperpolarized ligand of dihydrofolate reductase. J. Biomol. NMR, 2016. 65(1): p. 41-48.


Protein–ligand interaction is often characterized using polarization transfer by the intermolecular nuclear Overhauser effect (NOE). For such NOE experiments, hyperpolarization of nuclear spins presents the opportunity to increase the spin magnetization, which is transferred, by several orders of magnitude. Here, folic acid, a ligand of dihydrofolate reductase (DHFR), was hyperpolarized on 1H spins using dissolution dynamic nuclear polarization (D-DNP). Mixing hyperpolarized ligand with protein resulted in observable increases in protein 1H signal predominantly in the methyl group region of the spectra. Using 13C single quantum selection in a series of one-dimensional spectra, the carbon chemical shift ranges of the corresponding methyl groups can be elucidated. Signals observed in these hyperpolarized spectra could be confirmed using 3D isotope filtered NOESY spectra, although the hyperpolarized spectra were obtained in single scans. By further correlating the signal intensities observed in the D-DNP experiments with the occurrence of short distances in the crystal structure of the protein–ligand complex, the observed methyl proton signals could be matched to the chemical shifts of six amino acids in the active site of DHFR-folic acid binary complex. These data demonstrate that 13C chemical shift selection of protein resonances, combined with the intrinsic selectivity towards magnetization originating from the initially hyperpolarized spins, can be used for site specific characterization of protein–ligand interactions.

Friday, May 12, 2017

Hyperpolarized 13C pyruvate mouse brain metabolism with absorptive-mode EPSI at 1T


Miloushev, V.Z., et al., Hyperpolarized 13C pyruvate mouse brain metabolism with absorptive-mode EPSI at 1T. J Magn Reson, 2017. 275: p. 120-126.


The expected signal in echo-planar spectroscopic imaging experiments was explicitly modeled jointly in spatial and spectral dimensions. Using this as a basis, absorptive-mode type detection can be achieved by appropriate choice of spectral delays and post-processing techniques. We discuss the effects of gradient imperfections and demonstrate the implementation of this sequence at low field (1.05T), with application to hyperpolarized [1-13C] pyruvate imaging of the mouse brain. The sequence achieves sufficient signal-to-noise to monitor the conversion of hyperpolarized [1-13C] pyruvate to lactate in the mouse brain. Hyperpolarized pyruvate imaging of mouse brain metabolism using an absorptive-mode EPSI sequence can be applied to more sophisticated murine disease and treatment models. The simple modifications presented in this work, which permit absorptive-mode detection, are directly translatable to human clinical imaging and generate improved absorptive-mode spectra without the need for refocusing pulses.

Wednesday, May 10, 2017

Peptide and Protein Dynamics and Low-Temperature/DNP Magic Angle Spinning NMR #DNPNMR


Ni, Q.Z., et al., Peptide and Protein Dynamics and Low-Temperature/DNP Magic Angle Spinning NMR. J Phys Chem B, 2017.


In DNP MAS NMR experiments at ~80-110 K, the structurally important -13CH3 and -15NH3+ signals in MAS spectra of biological samples disappear due to the interference of the molecular motions with the 1H decoupling. Here we investigate the effect of these dynamic processes on the NMR lineshapes and signal intensities in several typical systems: (1) microcrystalline APG, (2) membrane protein bR, (3) amyloid fibrils PI3-SH3, (4) monomeric alanine-CD3 and (5) the pro-tonated and deuterated dipeptide N-Ac-VL over 78-300 K. In APG, the 3-site hopping of the Ala-Cbeta peak disappears com-pletely at 112 K, concomitant with the attenuation of CP signals from other 13C's and 15N's. Similarly, the 15N signal from Ala-NH3+ disappears ~173 K, concurrent with the attenuation in CP experiments of other 15N's as well as 13C's. In bR and PI3-SH3, the methyl groups are attenuated at ~95 K while all other 13C's remain unaffected. However, both systems exhibit substantial losses of intensity at ~243 K. Finally, with spectra of Ala and N-Ac-VL we show that it is possible to extract site specific dynamic data from the temperature dependence of the intensity losses. Furthermore, 2H labeling can assist with re-covering the spectral intensity. Thus, our study provides insight into the dynamic behavior of biological systems over a wide range of temperatures, and serves as a guide to optimizing the sensitivity and resolution of structural data in low temperature DNP MAS NMR spectra.

Monday, May 8, 2017

[NMR] PhD position in EPR & NMR at IPF Dresden

PhD position on EPR and NMR at the Leibniz Institute of Polymer Research Dresden, Germany

The Institute of Physical Chemistry and Polymer Physics, department Polyelectrolytes and Dispersions, at the Leibniz Institute of Polymer Research Dresden offers a position for a research assistant / PhD student (Chemist/Physicist). 

Project: Investigations on the dynamics of polyelectrolyte multilayers by spin-labeling and EPR spectroscopy (funded by Deutsche Forschungsgemeinschaft)

Salary 2/3 position TV-L EG 13 (26 hours/week). 

Start: asap
Duration: 31.03.2020
Qualification: MSc degree/diploma in Chemistry or Physics

Project description: Subject of the project are polyelectrolyte multilayers that can be prepared by alternating adsorption of polyanions and polycations using the Layer-by-layer technique on various substrates. It is a general and broadly applicable technique that enables manufacturing numerous different tailored structures. Polyelectrolyte multilayers find increasing attention in the targeted modification of surfaces and membranes. 

Various aspects, such as the growth mechanism, the internal structure of the layers as well as the dynamics are of fundamental interest for practical applications. While many details of the structures are known, there is much less knowledge for no less important dynamics of polymers in the multilayers. 

The aim of the project is to gain new insights into the mobility of chain segments of polyelectrolytes in multilayers and to show correlations between the internal structure and dynamics in these multilayers and resulting properties. 

In order to achieve this goal polyelectrolyte molecules are equipped with spin labels and incorporated in a defined manner in the PEM. The EPR spectroscopy offer the potential to study the rotational diffusion of the spin label linked to the macromolecule and to gain quantitative information about the mobility of polymer segments, which are complemented by NMR data,which are sensitive to longer time scales. 

The experimental investigations aim at the relationships between the chemical structure of the polyelectrolytes used, the conditions at the preparation of the PEM and the parameters of the surrounding medium (ionic strength, pH) and the mobility of polymer segments in different zones of the multilayer. 

The internal dynamics of the polyelectrolytes in the multilayers has an influence on the transport in the multilayer and through the multilayer when it is used as a membrane. The correlation of the temperature dependence of the polymer dynamics and the diffusion of small guest molecules results in insights in the mechanism of transport.

The Leibniz Institute of Polymer Research Dresden (IPF) is one of the largest polymer research facilities in Germany. As an institute of the Leibniz Association, the IPF is committed to carrying out application-oriented basic research. The focus of activities at the IPF is directed toward the advancement of basic scientific knowledge for the development of functional polymer materials and polymer materials with new or improved characteristics. Leading scientists of the IPF are at the same time appointed professors at the Technische Universität Dresden (TUD). Since 2011 the TUD has been one of the excellence universities in Germany. The IPF offers a stimulating working atmosphere for outstanding interdisciplinary research in one of the most beautiful cities of Germany. 

Dresden, the capital of Saxony, possesses an extraordinarily high density of research facilities which have made Dresden a leading research site, particularly in the fields of material research, microelectronics, and biotechnology. 

Applications including motivation letter, CV, should be submitted by e-mail as a single PDF document to the Department of Human Resources (with the No. 083-2017):

Leibniz-Institut für Polymerforschung Dresden e.V.
Frau Susanne Otto
Leiterin Personal und Soziales
Hohe Straße 6
01069 Dresden

Queries about the lab and the research project should be directed by e-mail to:
Ulrich Scheler Scheler@ipfdd.de or Uwe Lappan Lappan@ipfdd.de .

Job offer (in German)

Best regards,
Ulrich Scheler

-------------------------------------------------------------
Dr. Ulrich Scheler
Leibniz-Institut für Polymerforschung Dresden e.V.
Hohe Strasse 6
D-01069 Dresden, Germany
phone +49 351 4658 275
fax +49 351 4658 231
--------------------------------------------------------------


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

NMR web database:

[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:


-- 
Prof. Dr. Rasmus Linser
Ludwig-Maximilians-Universität München
Department Chemie
Butenandtstr. 5-13
81377 München


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

NMR web database:

Fumarase activity: an in vivo and in vitro biomarker for acute kidney injury


Nielsen, P.M., et al., Fumarase activity: an in vivo and in vitro biomarker for acute kidney injury. Scientific Reports, 2017. 7: p. 40812.


Renal ischemia/reperfusion injury (IRI) is a leading cause of acute kidney injury (AKI), and at present, there is a lack of reliable biomarkers that can diagnose AKI and measure early progression because the commonly used methods cannot evaluate single-kidney IRI. Hyperpolarized [1,4-13C2]fumarate conversion to [1,4-13C2]malate by fumarase has been proposed as a measure of necrosis in rat tumor models and in chemically induced AKI rats. Here we show that the degradation of cell membranes in connection with necrosis leads to elevated fumarase activity in plasma and urine and secondly that hyperpolarized [1,4-13C2]malate production 24 h after reperfusion correlates with renal necrosis in a 40-min unilateral ischemic rat model. Fumarase activity screening on bio-fluids can detect injury severity, in bilateral as well as unilateral AKI models, differentiating moderate and severe AKI as well as short- and long-term AKI. Furthermore after verification of renal injury by bio-fluid analysis the precise injury location can be monitored by in vivo measurements of the fumarase activity non-invasively by hyperpolarized [1,4-13C]fumarate MR imaging. The combined in vitro and in vivo biomarker of AKI responds to the essential requirements for a new reliable biomarker of AKI.

Friday, May 5, 2017

Tailored Polarizing Hybrid Solids with Nitroxide Radicals Localized in Mesostructured Silica Walls #DNPNMR


Silverio, D.L., et al., Tailored Polarizing Hybrid Solids with Nitroxide Radicals Localized in Mesostructured Silica Walls. Helvetica Chimica Acta, 2017: p. n/a-n/a.


Hyperpolarization by dynamic nuclear polarization relies on the microwave irradiation of paramagnetic radicals dispersed in molecular glasses to enhance the nuclear magnetic resonance (NMR) signals of target molecules. However, magnetic or chemical interactions between the radicals and the target molecules can lead to attenuation of the NMR signal through paramagnetic quenching and/or radical decomposition. Here we describe polarizing materials incorporating nitroxide radicals within the walls of the solids to minimize interactions between the radicals and the solute. These materials can hyperpolarize pure pyruvic acid, a particularly important substrate of clinical interest, while nitroxide radicals cannot be used, even when incorporated in the pores of silica, because of reactions between pyruvic acid and the radicals. The properties of these materials can be engineered by tuning the composition of the wall by introducing organic functionalities. This article is protected by copyright. All rights reserved.

Wednesday, May 3, 2017

Rotaxane probes for protease detection by 129Xe hyperCEST NMR


Slack, C.C., et al., Rotaxane probes for protease detection by 129Xe hyperCEST NMR. Chem Commun (Camb), 2017. 53(6): p. 1076-1079.


We report a CB6 rotaxane for the 129Xe hyperCEST NMR detection of matrix metalloprotease 2 (MMP-2) activity. MMP-2 is overexpressed in cancer tissue, and hence is a cancer marker. A peptide containing an MMP-2 recognition sequence was incorporated into the rotaxane, synthesized via CB6-promoted click chemistry. Upon cleavage of the rotaxane by MMP-2, CB6 became accessible for 129Xe@CB6 interactions, leading to protease-responsive hyperCEST activation.

Monday, May 1, 2017

Dynamic Polarization and Relaxation of 75As Nuclei in Silicon at High Magnetic Field and Low Temperature #DNPNMR


Järvinen, J., et al., Dynamic Polarization and Relaxation of 75As Nuclei in Silicon at High Magnetic Field and Low Temperature. Appl. Magn. Reson., 2017. 48(5): p. 473-483.


We present the results of experiments on dynamic nuclear polarization and relaxation of 75As in silicon crystals. Experiments are performed in strong magnetic fields of 4.6 T and temperatures below 1 K. At these conditions donor electron spins are fully polarized, and the allowed and forbidden electron spin resonance transitions are well resolved. We demonstrate effective nuclear polarization of 75As nuclei via the Overhauser effect on the time scale of several hundred seconds. Excitation of the forbidden transitions leads to a polarization through the solid effect. The relaxation rate of donor nuclei has strong temperature dependence characteristic of Orbach process.