Magnetic resonance (Gottingen, Germany)最新文献

{"title":"Magnetic expression in kerogen reveals impact on fluid transport.","authors":"Benjamin Nicot,&nbsp;Jean-Pierre Korb,&nbsp;Isabelle Jolivet,&nbsp;Hervé Vezin,&nbsp;Didier Gourier,&nbsp;Anne-Laure Rollet","doi":"10.5194/mr-3-125-2022","DOIUrl":"10.5194/mr-3-125-2022","url":null,"abstract":"<p><p>How can the transport of fluids in a confined and complex mixed organic/inorganic matrix be far below the expected value from a topological aspect? A good example of this situation is oil shales. Oil and gas shales are source rocks in which organic matter has matured to form hydrocarbons. They exhibit a dual porous network formed by the intertwining of mineral and organic pores that leads to very low permeability. Still, the exact origin of this extremely low permeability remains somehow unclear. The present communication addresses this important question and provides novel insights on the mechanisms that strongly hinder fluid diffusion in such materials. By combining nuclear and electronic magnetic resonance techniques with SEM imaging, we show evidence that magnetic interaction occurs in kerogen. This results from a magnetic coupling between vanadyl present in porphyrins and the organic matrix. We demonstrate that such coupling retards fluid diffusion and is reversible. This key dynamical feature explains the extremely low mobility of oil in shale rocks. This phenomenon may be a more general feature occurring in several systems where fluids are confined in a complex hierarchical matrix that embeds both organic and inorganic radicals resulting from the aging process.</p>","PeriodicalId":93333,"journal":{"name":"Magnetic resonance (Gottingen, Germany)","volume":" ","pages":"125-136"},"PeriodicalIF":0.0,"publicationDate":"2022-07-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10539839/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47494456","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Insight into the structure of black coatings of ancient Egyptian mummies by advanced electron magnetic resonance of vanadyl complexes.","authors":"Charles E Dutoit,&nbsp;Laurent Binet,&nbsp;Hervé Vezin,&nbsp;Océane Anduze,&nbsp;Agnès Lattuati-Derieux,&nbsp;Didier Gourier","doi":"10.5194/mr-3-111-2022","DOIUrl":"10.5194/mr-3-111-2022","url":null,"abstract":"<p><p>Ancient Egyptian mummies from the Late Period to the Greco-Roman Period were covered by a black coating consisting of complex and heterogeneous mixtures of conifer resins, wax, fat and oil with variable amounts of bitumen. Natural bitumen always contains traces of vanadyl porphyrin complexes that we used here as internal probes to explore the nanoscale environment of V<math><msup><mi></mi><mrow><mn>4</mn><mo>+</mo></mrow></msup></math> ions in these black coatings by electron nuclear double resonance (ENDOR) and hyperfine sub-level correlation spectroscopy (HYSCORE). Four types of vanadyl porphyrin complexes were identified from the analysis of <math><msup><mi></mi><mn>14</mn></msup></math>N hyperfine interactions. Three types (referred to as VO-P1, VO-P2 and VO-P3) are present in natural bitumen from the Dead Sea, among which VO-P1 and VO-P2 are also present in black coatings of mummies. The absence of VO-P3 in mummies, which is replaced by another complex, VO-P4, may be due to its transformation during preparation of the black matter for embalming. Analysis of <math><msup><mi></mi><mn>1</mn></msup></math>H hyperfine interaction shows that bitumen and other natural substances are intimately mixed in these black coatings, with aggregate sizes of bitumen increasing with the bitumen content but not exceeding a few nanometres.</p>","PeriodicalId":93333,"journal":{"name":"Magnetic resonance (Gottingen, Germany)","volume":"3 2","pages":"111-124"},"PeriodicalIF":0.0,"publicationDate":"2022-07-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10539842/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"71415934","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The effect of spin polarization on double electron-electron resonance (DEER) spectroscopy.","authors":"Sarah R Sweger, Vasyl P Denysenkov, Lutz Maibaum, Thomas F Prisner, Stefan Stoll","doi":"10.5194/mr-3-101-2022","DOIUrl":"10.5194/mr-3-101-2022","url":null,"abstract":"<p><p>Double electron-electron resonance (DEER) spectroscopy measures the distribution of distances between two electron spins in the nanometer range, often on doubly spin-labeled proteins, via the modulation of a refocused spin echo by the dipolar interaction between the spins. DEER is commonly conducted under conditions where the polarization of the spins is small. Here, we examine the DEER signal under conditions of high spin polarization, thermally obtainable at low temperatures and high magnetic fields, and show that the signal acquires a polarization-dependent out-of-phase component both for the intramolecular and intermolecular contributions. For the latter, this corresponds to a phase shift of the spin echo that is linear in the pump pulse position. We derive a compact analytical form of this phase shift and show experimental measurements using monoradical and biradical nitroxides at several fields and temperatures. The effect highlights a novel aspect of the fundamental spin physics underlying DEER spectroscopy.</p>","PeriodicalId":93333,"journal":{"name":"Magnetic resonance (Gottingen, Germany)","volume":" ","pages":"101-110"},"PeriodicalIF":0.0,"publicationDate":"2022-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10583274/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46573888","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Imatinib disassembles the regulatory core of Abelson kinase by binding to its ATP site and not by binding to its myristoyl pocket.","authors":"Stephan Grzesiek, Johannes Paladini, Judith Habazettl, Rajesh Sonti","doi":"10.5194/mr-3-91-2022","DOIUrl":"10.5194/mr-3-91-2022","url":null,"abstract":"<p><p>It was recently reported (Xie et al., 2022) that the Abelson tyrosine kinase (Abl) ATP-site inhibitor imatinib also binds to Abl's myristoyl binding pocket, which is the target of allosteric Abl inhibitors. This was based on a crystal structure of a truncated Abl kinase domain construct in complex with imatinib bound to the allosteric site as well as further isothermal titration calorimetry (ITC), NMR, and kinase activity data. Although imatinib's affinity for the allosteric site is significantly weaker (10 <math><mrow><mi>µ</mi></mrow></math>M) than for the ATP site (10 nM), imatinib binding to the allosteric site may disassemble the regulatory core of Abl, thereby stimulating kinase activity, in particular for Abl mutants with reduced imatinib ATP-site affinity. It was argued that the previously observed imatinib-induced opening of the Abl regulatory core (Skora et al., 2013; Sonti et al., 2018) may be caused by the binding of imatinib to the allosteric site and not to the ATP site. We show here that this is not the case but that indeed imatinib binding to the ATP site induces the opening of the regulatory core at nanomolar concentrations. This agrees with findings that other type-II ATP-site inhibitors (nilotinib, ponatinib) disassemble the regulatory core despite demonstrated negligible binding to the allosteric site.</p>","PeriodicalId":93333,"journal":{"name":"Magnetic resonance (Gottingen, Germany)","volume":"3 1","pages":"91-99"},"PeriodicalIF":0.0,"publicationDate":"2022-05-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10539847/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"71415929","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A portable NMR platform with arbitrary phase control and temperature compensation.","authors":"Qing Yang,&nbsp;Jianyu Zhao,&nbsp;Frederik Dreyer,&nbsp;Daniel Krüger,&nbsp;Jens Anders","doi":"10.5194/mr-3-77-2022","DOIUrl":"10.5194/mr-3-77-2022","url":null,"abstract":"<p><p>In this paper, we present a custom-designed nuclear magnetic resonance (NMR) platform based on a broadband complementary metal-oxide-semiconductor (CMOS) NMR-on-a-chip transceiver and a synchronous reference signal generator, which features arbitrary phase control of the excitation pulse in combination with phase-coherent detection at a non-zero intermediate frequency (IF). Moreover, the presented direct digital synthesis (DDS)-based frequency generator enables a digital temperature compensation scheme similar to classical field locking without the need for additional hardware. NMR spectroscopy and relaxometry measurements verify the functionality of the proposed frequency reference and temperature compensation scheme as well as the overall state-of-the-art performance of the presented system.</p>","PeriodicalId":93333,"journal":{"name":"Magnetic resonance (Gottingen, Germany)","volume":" ","pages":"77-90"},"PeriodicalIF":0.0,"publicationDate":"2022-05-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10539832/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44181278","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Localising nuclear spins by pseudocontact shifts from a single tagging site.","authors":"Henry W Orton, Elwy H Abdelkader, Lydia Topping, Stephen J Butler, Gottfried Otting","doi":"10.5194/mr-3-65-2022","DOIUrl":"10.5194/mr-3-65-2022","url":null,"abstract":"<p><p>Ligating a protein at a specific site with a tag molecule containing a paramagnetic metal ion provides a versatile way of generating pseudocontact shifts (PCSs) in nuclear magnetic resonance (NMR) spectra. PCSs can be observed for nuclear spins far from the tagging site, and PCSs generated from multiple tagging sites have been shown to enable highly accurate structure determinations at specific sites of interest, even when using flexible tags, provided the fitted effective magnetic susceptibility anisotropy (<math><mrow><mi>Δ</mi><mi>χ</mi></mrow></math>) tensors accurately back-calculate the experimental PCSs measured in the immediate vicinity of the site of interest. The present work investigates the situation where only the local structure of a protein region or bound ligand is to be determined rather than the structure of the entire molecular system. In this case, the need for gathering structural information from tags deployed at multiple sites may be queried. Our study presents a computational simulation of the structural information available from samples produced with single tags attached at up to six different sites, up to six different tags attached to a single site, and in-between scenarios. The results indicate that the number of tags is more important than the number of tagging sites. This has important practical implications, as it is much easier to identify a single site that is suitable for tagging than multiple ones. In an initial experimental demonstration with the ubiquitin mutant S57C, PCSs generated with four different tags at a single site are shown to accurately pinpoint the location of amide protons in different segments of the protein.</p>","PeriodicalId":93333,"journal":{"name":"Magnetic resonance (Gottingen, Germany)","volume":" ","pages":"65-76"},"PeriodicalIF":0.0,"publicationDate":"2022-05-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10539793/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45627325","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"SORDOR pulses: expansion of the Böhlen-Bodenhausen scheme for low-power broadband magnetic resonance.","authors":"Jens D Haller,&nbsp;David L Goodwin,&nbsp;Burkhard Luy","doi":"10.5194/mr-3-53-2022","DOIUrl":"10.5194/mr-3-53-2022","url":null,"abstract":"<p><p>A novel type of efficient broadband pulse, called second-order phase dispersion by optimised rotation (SORDOR), has recently been introduced. In contrast to adiabatic excitation, SORDOR-90 pulses provide effective transverse 90<math><msup><mi></mi><mo>∘</mo></msup></math> rotations throughout their bandwidth, with a quadratic offset dependence of the phase in the <math><mrow><mi>x</mi><mo>,</mo><mi>y</mi></mrow></math> plane. Together with phase-matched SORDOR-180 pulses, this enables the Böhlen-Bodenhausen broadband refocusing approach for linearly frequency-swept pulses to be extended to any type of 90<math><msup><mi></mi><mo>∘</mo></msup></math>/180<math><msup><mi></mi><mo>∘</mo></msup></math> pulse-delay sequence. Example pulse shapes are characterised in theory and experiment, and an example application is given with a <math><mrow><msup><mi></mi><mn>19</mn></msup><mi>F</mi></mrow></math>-PROJECT experiment for measuring relaxation times with reduced distortions due to <math><mi>J</mi></math>-coupling evolution.</p>","PeriodicalId":93333,"journal":{"name":"Magnetic resonance (Gottingen, Germany)","volume":"3 1","pages":"53-63"},"PeriodicalIF":0.0,"publicationDate":"2022-04-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10539771/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"71415931","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Radiation damping strongly perturbs remote resonances in the presence of homonuclear mixing.","authors":"Philippe Pelupessy","doi":"10.5194/mr-3-43-2022","DOIUrl":"10.5194/mr-3-43-2022","url":null,"abstract":"<p><p>In this work, it is experimentally shown that the weak oscillating magnetic field (known as the \"radiation damping\" field) caused by the inductive coupling between the transverse magnetization of nuclei and the radio frequency circuit perturbs remote resonances when homonuclear total correlation mixing is applied. Numerical simulations are used to rationalize this effect.</p>","PeriodicalId":93333,"journal":{"name":"Magnetic resonance (Gottingen, Germany)","volume":" ","pages":"43-51"},"PeriodicalIF":0.0,"publicationDate":"2022-02-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10539763/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43595406","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Spin relaxation: is there anything new under the Sun?","authors":"Bogdan A Rodin, Daniel Abergel","doi":"10.5194/mr-3-27-2022","DOIUrl":"10.5194/mr-3-27-2022","url":null,"abstract":"<p><p>Spin relaxation has been at the core of many studies since the early days of nuclear magnetic resonance (NMR) and the underlying theory worked out by its founding fathers. This Bloch-Redfield-Abraham relaxation theory has been recently reinvestigated () in the perspective of Lindblad theory of quantum Markovian master equations in order to account for situations where the widely used semi-classical relaxation theory breaks down. In this article, we review the conventional approach of quantum mechanical theory of NMR relaxation and show that, under the usual assumptions, it is equivalent to the Lindblad formulation. We also comment on the debate on semi-classical versus quantum versions of spectral density functions involved in relaxation.</p>","PeriodicalId":93333,"journal":{"name":"Magnetic resonance (Gottingen, Germany)","volume":" ","pages":"27-41"},"PeriodicalIF":0.0,"publicationDate":"2022-02-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10539756/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46756307","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Correction of field instabilities in biomolecular solid-state NMR by simultaneous acquisition of a frequency reference.","authors":"Václav Římal, Morgane Callon, Alexander A Malär, Riccardo Cadalbert, Anahit Torosyan, Thomas Wiegand, Matthias Ernst, Anja Böckmann, Beat H Meier","doi":"10.5194/mr-3-15-2022","DOIUrl":"10.5194/mr-3-15-2022","url":null,"abstract":"<p><p>With the advent of faster magic-angle spinning (MAS) and higher magnetic fields, the resolution of biomolecular solid-state nuclear magnetic resonance (NMR) spectra has been continuously increasing. As a direct consequence, the always narrower spectral lines, especially in proton-detected spectroscopy, are also becoming more sensitive to temporal instabilities of the magnetic field in the sample volume. Field drifts in the order of tenths of parts per million occur after probe insertion or temperature change, during cryogen refill, or are intrinsic to the superconducting high-field magnets, particularly in the months after charging. As an alternative to a field-frequency lock based on deuterium solvent resonance rarely available for solid-state NMR, we present a strategy to compensate non-linear field drifts using simultaneous acquisition of a frequency reference (SAFR). It is based on the acquisition of an auxiliary 1D spectrum in each scan of the experiment. Typically, a small-flip-angle pulse is added at the beginning of the pulse sequence. Based on the frequency of the maximum of the solvent signal, the field evolution in time is reconstructed and used to correct the raw data after acquisition, thereby acting in its principle as a digital lock system. The general applicability of our approach is demonstrated on 2D and 3D protein spectra during various situations with a non-linear field drift. SAFR with small-flip-angle pulses causes no significant loss in sensitivity or increase in experimental time in protein spectroscopy. The correction leads to the possibility of recording high-quality spectra in a typical biomolecular experiment even during non-linear field changes in the order of 0.1 ppm h<math><msup><mi></mi><mrow><mo>-</mo><mn>1</mn></mrow></msup></math> without the need for hardware solutions, such as stabilizing the temperature of the magnet bore. The improvement of linewidths and peak shapes turns out to be especially important for <math><msup><mi></mi><mn>1</mn></msup></math>H-detected spectra under fast MAS, but the method is suitable for the detection of carbon or other nuclei as well.</p>","PeriodicalId":93333,"journal":{"name":"Magnetic resonance (Gottingen, Germany)","volume":"3 1","pages":"15-26"},"PeriodicalIF":0.0,"publicationDate":"2022-02-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10539777/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"71415928","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}