Journal of Magnetic Resonance (1969)最新文献

{"title":"Fast spectral-spatial EPR imaging with modulated gradient and simultaneous field scan","authors":"Thomas Herrling,&nbsp;Kai-Uwe Thiessenhusen,&nbsp;Uwe Ewert","doi":"10.1016/0022-2364(92)90370-M","DOIUrl":"https://doi.org/10.1016/0022-2364(92)90370-M","url":null,"abstract":"<div><p>Spectral spatial EPR imaging with <em>mo</em>dulated gradient and simultaneous field scan (MOSS) was investigated with regard to its spectral and spatial resolution and its total measuring time. The gradient coil system is used to overlap the fast field scan with a modulated field gradient. The complete image was measured in 64 s, utilizing a gradient-modulation frequency of 66 s⁻¹. This technique does not require image reconstruction. The influence of different modulation functions (cosine and triangular) and of a partial blanking of the applied cosine-modulated signal on the spectral-spatial image is discussed. The partial-blanking method is most suitable for fast imaging and best image quality.</p></div>","PeriodicalId":100800,"journal":{"name":"Journal of Magnetic Resonance (1969)","volume":"100 1","pages":"Pages 123-138"},"PeriodicalIF":0.0,"publicationDate":"1992-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0022-2364(92)90370-M","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91632261","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Long-range heteronuclear spin locking (HSL) and its application to peptide sequencing","authors":"Maritherese Tokles,&nbsp;Gerard S Hatvany,&nbsp;Peter L Rinaldi","doi":"10.1016/0022-2364(92)90371-D","DOIUrl":"10.1016/0022-2364(92)90371-D","url":null,"abstract":"<div><p>In this paper, the utility of heteronuclear-spin-locking 2D NMR experiments for structure elucidation from long-range interactions is demonstrated. Long-range {¹H}¹³C heteronuclear-shift-correlation spectra via spin locking provides peptide-sequencing information for gramicidin-S with considerably better sensitivity than was previously obtained with other long-range shift-correlation methods such as HOESY and COLOC.</p></div>","PeriodicalId":100800,"journal":{"name":"Journal of Magnetic Resonance (1969)","volume":"100 1","pages":"Pages 139-145"},"PeriodicalIF":0.0,"publicationDate":"1992-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0022-2364(92)90371-D","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84947630","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Measurement of heteronuclear NOE enhancements in biological macromolecules. A convenient pulse sequence for use with aqueous solutions","authors":"David Neuhaus,&nbsp;Carlo P.M van Mierlo","doi":"10.1016/0022-2364(92)90382-H","DOIUrl":"10.1016/0022-2364(92)90382-H","url":null,"abstract":"","PeriodicalId":100800,"journal":{"name":"Journal of Magnetic Resonance (1969)","volume":"100 1","pages":"Pages 221-228"},"PeriodicalIF":0.0,"publicationDate":"1992-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0022-2364(92)90382-H","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74369672","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Consideration of random errors in the quantitative imaging of NMR relaxation","authors":"Simon J Doran,&nbsp;John J Attard,&nbsp;Timothy P.L Roberts,&nbsp;T Adrian Carpenter,&nbsp;Laurance D Hall","doi":"10.1016/0022-2364(92)90369-I","DOIUrl":"https://doi.org/10.1016/0022-2364(92)90369-I","url":null,"abstract":"<div><p>Quantitative magnetic resonance imaging is a field whose development is at an early stage. Relatively little work has been done to assess the reliability of the values obtained from the quantitative maps previously presented. Here, the problem of spatial mapping of <em>T</em>₁ relaxation is studied. The effects of random errors on the results of imaging experiments incorporating saturation-recovery and fast inversion-recovery measurements are examined. Consideration is given to various factors affecting experimental design, common to all implementations of these techniques: the <span><math><mtext>S</mtext><mtext>N</mtext></math></span> ratio, the number of relaxation points sampled, and their distribution. No attempt has been made to assess different fitting algorithms. It is demonstrated that quantitative image data can be well modeled by simulations, leading to the conclusion that a <em>T</em>₁-imaging experiment can be regarded simply as a set of <em>independent</em><em>T</em>₁ measurements, one on each image voxel. Results from previous work on bulk <em>T</em>₁ measurements are therefore applicable to quantitative imaging and are used to design an efficient imaging experiment, under a typical clinical time constraint of approximately one hour.</p></div>","PeriodicalId":100800,"journal":{"name":"Journal of Magnetic Resonance (1969)","volume":"100 1","pages":"Pages 101-122"},"PeriodicalIF":0.0,"publicationDate":"1992-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0022-2364(92)90369-I","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91632258","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Baseline flattening by automatic phasing of dispersive water signals","authors":"Bruce A Johnson","doi":"10.1016/0022-2364(92)90377-J","DOIUrl":"https://doi.org/10.1016/0022-2364(92)90377-J","url":null,"abstract":"","PeriodicalId":100800,"journal":{"name":"Journal of Magnetic Resonance (1969)","volume":"100 1","pages":"Pages 189-194"},"PeriodicalIF":0.0,"publicationDate":"1992-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0022-2364(92)90377-J","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91678248","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Improved linear prediction of damped NMR signals using modified “forward-backward” linear prediction","authors":"Guang Zhu ,&nbsp;Ad Bax","doi":"10.1016/0022-2364(92)90379-L","DOIUrl":"https://doi.org/10.1016/0022-2364(92)90379-L","url":null,"abstract":"","PeriodicalId":100800,"journal":{"name":"Journal of Magnetic Resonance (1969)","volume":"100 1","pages":"Pages 202-207"},"PeriodicalIF":0.0,"publicationDate":"1992-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0022-2364(92)90379-L","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91678252","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A “magic-angle” sample-spinning nuclear magnetic resonance spectroscopic study of interference effects in the nuclear spin relaxation of polymers","authors":"John Chung ,&nbsp;Eric Oldfield,&nbsp;André Thevand,&nbsp;Larry Werbelow","doi":"10.1016/0022-2364(92)90366-F","DOIUrl":"10.1016/0022-2364(92)90366-F","url":null,"abstract":"<div><p>The proton-coupled, carbon-13 “magic-angle” sample-spinning nuclear magnetic resonance spin-lattice relaxation behavior of poly (<em>cis</em>-isoprene) and poly (<em>cis</em>-butadiene) as a function of temperature is reported. Analysis of the relaxation behavior of the methine carbons reveals strong temporal correlations between the ¹³CH dipolar and ¹³C anisotropic chemical shielding interactions. Equations are presented which enable the interpretation of these interferences for non-axially symmetric shielding tensors, subject to cylindrically symmetric reorientation. In the context of these expressions, the results indicate that the methine moiety in each of the two polymers executes relatively rapid, isotropic motions, on the time scale of the carbon-13 Larmor frequency. It is also shown that in certain polymeric systems, the sign of the interference term may change with frequency. This intriguing property provides additional insight into the relative reorientational anisotropies of the low- and high-frequency motions, and the specific case of the spin-lattice relaxation and differential line broadening of the methine carbons in poly (cis-isoprene) and poly (<em>trans</em>-isoprene) is considered in detail.</p></div>","PeriodicalId":100800,"journal":{"name":"Journal of Magnetic Resonance (1969)","volume":"100 1","pages":"Pages 69-81"},"PeriodicalIF":0.0,"publicationDate":"1992-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0022-2364(92)90366-F","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86301839","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Improved resolution of spectral splittings via bayesian spectral analysis","authors":"K Shay Vines,&nbsp;Ronald F Evilia,&nbsp;Scott L Whittenburg","doi":"10.1016/0022-2364(92)90378-K","DOIUrl":"10.1016/0022-2364(92)90378-K","url":null,"abstract":"","PeriodicalId":100800,"journal":{"name":"Journal of Magnetic Resonance (1969)","volume":"100 1","pages":"Pages 195-201"},"PeriodicalIF":0.0,"publicationDate":"1992-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0022-2364(92)90378-K","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84646015","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Natural-abundance 13C chemical-shift editing of homonuclearcorrelated spectral data for carbohydrates via heteronuclear 3D NMR spectroscopy","authors":"G.V.T Swapna,&nbsp;R Ramachandran","doi":"10.1016/0022-2364(92)90374-G","DOIUrl":"https://doi.org/10.1016/0022-2364(92)90374-G","url":null,"abstract":"","PeriodicalId":100800,"journal":{"name":"Journal of Magnetic Resonance (1969)","volume":"100 1","pages":"Pages 166-170"},"PeriodicalIF":0.0,"publicationDate":"1992-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0022-2364(92)90374-G","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91590515","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Theory and experimental results of transfer NOE experiments. II. The influence of residual mobility and relaxation centers inside the protein on the size of transfer NOEs","authors":"N.R Nirmala ,&nbsp;G.M Lippens ,&nbsp;K Hallenga","doi":"10.1016/0022-2364(92)90363-C","DOIUrl":"https://doi.org/10.1016/0022-2364(92)90363-C","url":null,"abstract":"<div><p>Experimental evidence is presented for a strong dependence of transfer NOE values on the Larmor frequency for certain residues of a peptide in its complex with a protein. This dependency has been explained by residual mobility in these residues of the peptide when bound. As a consequence, effective correlation times exist for some proton-proton pairs that are at least one order of magnitude smaller than expected for a rigid complex. This is shown to be the main reason for the failure to observe certain transfer NOEs in such a complex when studied at proton frequencies of 400 MHz or less. Another factor that can reduce the size of transfer NOES is the possibility of leakage of magnetization toward relaxation centers inside the protein. We have observed several intermolecular NOE cross peaks demonstrating such an intermolecular exchange of magnetization. The influence of cross relaxation to relaxation centers in the protein on the buildup and magnitude of proton transfer NOES for the bound and the free ligand is described in a model of the ligand-protein system that consists of a set of Bloch equations in which chemical exchange, transfer of magnetization, and relaxation sinks in the protein have been included. Simulations have been done for the cases of fast and intermediate exchange on the spin-lattice relaxation time scale while in all cases bound and free ligand signals were assumed to be in fast exchange on the chemical-shift scale. It is found that the magnitude of intramolecular transfer NOEs is reduced by the presence of cross relaxation from the peptide into the protein, in particular when the protein has relaxation centers such as methyl groups and aromatic rings. It is shown that these effects can reduce the size of transfer NOE effects by an order of magnitude for those ligand protons that are directly in contact with the protein. The simulations for ligand protein concentration ratios of 2, 10, and 100 with various numbers of relaxation sinks in the protein show that concentration ratios and mixing times must be optimized in order to observe sizeable transfer NOES in 2D NMR experiments. The influence of these effects on the accuracy of distances determined via transfer NOEs is also discussed.</p></div>","PeriodicalId":100800,"journal":{"name":"Journal of Magnetic Resonance (1969)","volume":"100 1","pages":"Pages 25-42"},"PeriodicalIF":0.0,"publicationDate":"1992-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0022-2364(92)90363-C","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91632379","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}