共查询到20条相似文献,搜索用时 31 毫秒
1.
Dr. Ümit Akbey Dr. Andrew J. Nieuwkoop Dr. Sebastian Wegner Anja Voreck Dr. Britta Kunert Dr. Priyanga Bandara Dr. Frank Engelke Prof. Dr. Niels Chr. Nielsen Prof. Dr. Hartmut Oschkinat 《Angewandte Chemie (International ed. in English)》2014,53(9):2438-2442
1H‐detected magic‐angle spinning NMR experiments facilitate structural biology of solid proteins, which requires using deuterated proteins. However, often amide protons cannot be back‐exchanged sufficiently, because of a possible lack of solvent exposure. For such systems, using 2H excitation instead of 1H excitation can be beneficial because of the larger abundance and shorter longitudinal relaxation time, T1, of deuterium. A new structure determination approach, “quadruple‐resonance NMR spectroscopy”, is presented which relies on an efficient 2H‐excitation and 2H‐13C cross‐polarization (CP) step, combined with 1H detection. We show that by using 2H‐excited experiments better sensitivity is possible on an SH3 sample recrystallized from 30 % H2O. For a membrane protein, the ABC transporter ArtMP in native lipid bilayers, different sets of signals can be observed from different initial polarization pathways, which can be evaluated further to extract structural properties. 相似文献
2.
Damien Jeannerat Dawn Ronan Yoann Baudry Andr Pinto Jean‐Paul Saulnier Stefan Matile 《Helvetica chimica acta》2004,87(9):2190-2207
The usefulness of computer‐assisted aliasing to secure maximal resolution of signal clusters in 1H‐ and 13C‐NMR spectra (which is essential for structure determination by HMBC 2D NMR spectroscopy) in minimal acquisition time is exemplified by the complete characterization of the two complementary p‐octiphenyls 1 and 2 with complex substitution patterns. The need for digital resolution near 1 Hz/pt to dissect the extensive signal clusters in the NMR spectra of these refined oligomers excluded structure determination under routine conditions. High resolution was secured by exploiting the low signal density in the 13C dimension of HMBC spectra by using computer‐assisted aliasing to maximize signal density. Based on the observed shifts in DEPT and 1H‐decoupled 13C‐NMR spectra of 1 and 2 , computer‐assisted aliasing allowed to reduce the number of required time increments by a factor of 20 to 30 compared to full‐width spectra with identical resolution. Without signal‐to‐noise constraints, this computer‐assisted aliasing reduced the acquisition time for high‐resolution NMR spectra needed for complete characterization of refined oligomers 1 and 2 by the same factor (e.g., from over a day to about an hour). With resolved signal clusters in fully aliased HSQC and HMBC spectra, unproblematic structure determination of 1 and 2 is demonstrated by unambiguous assignment of all C‐ and H‐atoms. These findings demonstrate that computer‐assisted aliasing of the underexploited 13C dimension makes extensive molecular complexity accessible by conventional multidimensional heteronuclear NMR experiments without extraordinary efforts. 相似文献
3.
Real‐Time Band‐Selective Homonuclear Proton Decoupling for Improving Sensitivity and Resolution in Phase‐Sensitive J‐Resolved Spectroscopy
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Real‐time band‐selective homonuclear 1H decoupling during data acquisition of z‐filtered J‐resolved spectroscopy produces 1H‐decoupled 1H NMR spectra and leads to sensitivity enhancement and improved resolution, and thus aids the measurement of J couplings and residual dipolar couplings in crowded regions of 1H NMR spectrum. High quality spectra from peptides, organic molecules, and also from enantiomers dissolved in weakly aligned chiral media are reported. 相似文献
4.
A. S. Brar Rajeev Kumar 《Journal of polymer science. Part A, Polymer chemistry》2002,40(14):2225-2236
N‐vinyl‐2‐pyrrolidone/methyl acrylate (V/M) copolymers were prepared by free‐radical bulk polymerization using benzoyl peroxide as an initiator. The copolymer composition of these copolymers was calculated from 1H NMR spectra. The radical reactivity ratios for N‐vinyl‐2‐pyrrolidone (V) and methyl acrylate (M) were rV = 0.09, rM = 0.44. These reactivity ratios for the copolymerization of V and M were determined using the Kelen–Tudos and nonlinear least‐squares error‐in‐variable methods. The 13C{1H} and 1H NMR spectra of these copolymers overlapped and were complex. The complete spectral assignment of the 13C and 1H NMR spectra were done with distortionless enhancement by polarization transfer and two dimensional 13C‐1H heteronuclear single quantum correlation spectroscopic experiments. The two‐dimensional 1H‐1H homonuclear total correlation spectroscopic NMR spectrum showed the various bond interactions, thus inferring the possible structure of the copolymers. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2225–2236, 2002 相似文献
5.
A. S. Brar Rajeev Kumar 《Journal of polymer science. Part A, Polymer chemistry》2002,40(15):2717-2717
N‐vinyl‐2‐pyrrolidone/methyl acrylate (V/M) copolymers were prepared by free‐radical bulk polymerization using benzoyl peroxide as an initiator. The copolymer composition of these copolymers was calculated from 1H NMR spectra. The radical reactivity ratios for N‐vinyl‐2‐pyrrolidone (V) and methyl acrylate (M) were rV = 0.09, rM = 0.44. These reactivity ratios for the copolymerization of V and M were determined using the Kelen–Tudos and nonlinear least‐squares error‐in‐variable methods. The 13C{1H} and 1H NMR spectra of these copolymers overlapped and were complex. The complete spectral assignment of the 13C and 1H NMR spectra were done with distortionless enhancement by polarization transfer and two dimensional 13C‐1H heteronuclear single quantum correlation spectroscopic experiments. The two‐dimensional 1H‐1H homonuclear total correlation spectroscopic NMR spectrum showed the various bond interactions, thus inferring the possible structure of the copolymers. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2225–2236, 2002 相似文献
6.
《Magnetic resonance in chemistry : MRC》2002,40(8):541-544
Two novel oligosaccharides, mono‐ and difructosyllactosucrose {[O‐β‐D ‐fructofuranosyl‐(2 → 1)]n‐β‐D ‐fructofuranosyl‐O‐[β‐D ‐galactopyranosyl‐(1 → 4)]‐α‐D ‐glucopyranoside, n = 1 and 2} were synthesized using 1F‐fructosyltransferase purified form roots of asparagus (Asparagus officinalis L.). Their 1H and 13C NMR spectra were assigned using several NMR techniques. The spectral analysis was started from two anomeric methines of aldose units, galactose and glucose, since they showed separate characteristic signals in their 1H and 13C NMR spectra. After assignments of all the 1H and 13C signals of two units of aldose, they were discriminated as galactose and glucose using proton–proton coupling constants. The HMBC spectrum revealed the galactose residue attached to C‐4 of glucose, fructose residue attached to the C‐1 of glucose, and further fructosyl fructose linkage extended from the glucosyl fructose residues. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
7.
Site‐Resolved Backbone and Side‐Chain Intermediate Dynamics in a Carbohydrate‐Binding Module Protein Studied by Magic‐Angle Spinning NMR Spectroscopy
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Hadar Ivanir‐Dabora Evgeny Nimerovsky Prof. P. K. Madhu Dr. Amir Goldbourt 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(30):10778-10785
Magic‐angle spinning solid‐state NMR spectroscopy has been applied to study the dynamics of CBM3b–Cbh9A from Clostridium thermocellum (ctCBM3b), a cellulose binding module protein. This 146‐residue protein has a nine‐stranded β‐sandwich fold, in which 35 % of the residues are in the β‐sheet and the remainder are composed of loops and turns. Dynamically averaged 1H‐13C dipolar coupling order parameters were extracted in a site‐specific manner by using a pseudo‐three‐dimensional constant‐time recoupled separated‐local‐field experiment (dipolar‐chemical shift correlation experiment; DIPSHIFT). The backbone‐Cα and Cβ order parameters indicate that the majority of the protein, including turns, is rigid despite having a high content of loops; this suggests that restricted motions of the turns stabilize the loops and create a rigid structure. Water molecules, located in the crystalline interface between protein units, induce an increased dynamics of the interface residues thereby lubricating crystal water‐mediated contacts, whereas other crystal contacts remain rigid. 相似文献
8.
Ana Snchez‐Migalln Antonio delaHoz Concepcin Lpez RosaM. Claramunt Lourdes Infantes Sam Motherwell Kenneth Shankland Harriott Nowell Ibon Alkorta Jos Elguero 《Helvetica chimica acta》2003,86(4):1026-1039
The crystal structure of 1‐hydroxy‐2,4,5‐triphenyl‐1H‐imidazole 3‐oxide ( 1 ) has been determined from laboratory X‐ray powder‐diffraction data. The two independent molecules in the asymmetric unit form chains via O? H???O hydrogen bonds related by a twofold screw axis. One of the O???O distances is extremely short (2.32(1) and 2.43(1) Å). Solid‐state NMR spectroscopy (CPMAS) combined with calculation of absolute shieldings (GIAO/B3LYP/6‐31G*) allowed us to determine that the compound behaves as if the O? H???O hydrogen bond has the proton in the middle (single‐well potential), resulting in the near identity of both 15N‐NMR signals. 相似文献
9.
Michael F. Brown Karina Martínez‐Mayorga Koji Nakanishi Gilmar F. J. Salgado Andrey V. Struts 《Photochemistry and photobiology》2009,85(2):442-453
Solid‐state NMR spectroscopy gives a powerful avenue for investigating G protein‐coupled receptors and other integral membrane proteins in a native‐like environment. This article reviews the use of solid‐state 2H NMR to study the retinal cofactor of rhodopsin in the dark state as well as the meta I and meta II photointermediates. Site‐specific 2H NMR labels have been introduced into three regions (methyl groups) of retinal that are crucially important for the photochemical function of rhodopsin. Despite its phenomenal stability 2H NMR spectroscopy indicates retinal undergoes rapid fluctuations within the protein binding cavity. The spectral lineshapes reveal the methyl groups spin rapidly about their three‐fold (C3) axes with an order parameter for the off‐axial motion of For the dark state, the 2H NMR structure of 11‐cis‐retinal manifests torsional twisting of both the polyene chain and the β‐ionone ring due to steric interactions of the ligand and the protein. Retinal is accommodated within the rhodopsin binding pocket with a negative pretwist about the C11=C12 double bond. Conformational distortion explains its rapid photochemistry and reveals the trajectory of the 11‐cis to trans isomerization. In addition, 2H NMR has been applied to study the retinylidene dynamics in the dark and light‐activated states. Upon isomerization there are drastic changes in the mobility of all three methyl groups. The relaxation data support an activation mechanism whereby the β‐ionone ring of retinal stays in nearly the same environment, without a large displacement of the ligand. Interactions of the β‐ionone ring and the retinylidene Schiff base with the protein transmit the force of the retinal isomerization. Solid‐state 2H NMR thus provides information about the flow of energy that triggers changes in hydrogen‐bonding networks and helix movements in the activation mechanism of the photoreceptor. 相似文献
10.
An Efficient Labelling Approach to Harness Backbone and Side‐Chain Protons in 1H‐Detected Solid‐State NMR Spectroscopy
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Deni Mance Dr. Tessa Sinnige Mohammed Kaplan Siddarth Narasimhan Mark Daniëls Dr. Klaartje Houben Prof. Marc Baldus Dr. Markus Weingarth 《Angewandte Chemie (International ed. in English)》2015,54(52):15799-15803
1H‐detection can greatly improve spectral sensitivity in biological solid‐state NMR (ssNMR), thus allowing the study of larger and more complex proteins. However, the general requirement to perdeuterate proteins critically curtails the potential of 1H‐detection by the loss of aliphatic side‐chain protons, which are important probes for protein structure and function. Introduced herein is a labelling scheme for 1H‐detected ssNMR, and it gives high quality spectra for both side‐chain and backbone protons, and allows quantitative assignments and aids in probing interresidual contacts. Excellent 1H resolution in membrane proteins is obtained, the topology and dynamics of an ion channel were studied. This labelling scheme will open new avenues for the study of challenging proteins by ssNMR. 相似文献
11.
《Magnetic resonance in chemistry : MRC》2003,41(4):301-303
4‐Methyl‐6,8‐dihydroxy‐7H‐benz[de]anthracen‐7‐one was isolated from the sap of Aloe by column chromatography. Its 1H and 13C NMR spectra were completely assigned by utilizing two‐dimensional 1H‐detected heteronuclear one‐bond (HMQC) and multiple‐bond (HMBC) chemical shift correlation experiments together with 1H–1H COSY and DEPT techniques. These techniques were also valuable in assigning the protons and carbons of those benzanthrone compounds which were previously incompletely reported because of the overlap of proton signals. The molecular structure was elucidated by 2D NMR analysis. The spectral properties (MS, IR and UV) are also presented. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
12.
Iodine‐Catalyzed Synthesis of Spiro[1,3,4‐benzotriazepine‐2,3′‐indole]‐2′,5(1H,1′H)‐diones under Mild Conditions
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The I2‐catalyzed preparation of spiro[1,3,4‐benzotriazepine‐2,3′‐indole]‐2′,5(1H,1′H)‐diones from 2‐aminobenzohydrazide and isatins in MeCN at room temperature in good‐to‐excellent yields is described. The structure of 3 was corroborated spectroscopically (IR, 1H‐ and 13C‐NMR, and EI‐MS data). A plausible mechanism for this type of reaction is proposed (Scheme 2). 相似文献
13.
Fused 3,6‐disubstituted triazolothiadiazoles were synthesized in good yield from a rapid and convenient oxidative cyclization of N‐heteroaryl‐substituted hydrazones promoted by chloramine‐T trihydrate at ambient temperature. The structure of the synthesized compounds was confirmed by FTIR, 1H NMR, 13C NMR, and mass spectral data. The synthesized compounds were evaluated for their antioxidant and antitubercular activities. All the compounds 5a‐i and 6a‐i showed good antitubercular activity. However, only compounds 5a‐i showed good antioxidant activity. 相似文献
14.
Considerable work has been invested in the area of computer‐assisted structure elucidation (CASE) methods. As NMR techniques have been developed that provide more effective atom‐to‐atom connectivity information, it has become theoretically possible to do de novo structure elucidation based on 2D NMR datasets recorded for an unknown molecule. However, as annular (ring) nitrogen atoms become more prevalent in complex chemical structures, the ability to rely solely on 1H and 13C homo‐ and hetero‐nuclear direct and long‐range connectivity information to solve a structure correspondingly diminishes. Hence, we now wish to report the results of an investigation into the application of CASE methods with and without long‐range 1H‐15N data using posaconazole as a model compound, which has eight annular nitrogens in its structure. With the inclusion of 1H‐15N data long‐range data, the structure could be successfully determined in a few hours. Excluding the 1H‐15N data caused the program to generate millions of candidate structures, none of which fit the data well enough to be stored. 相似文献
15.
Dr. Shakeel A. Shahid Dr. Madhu Nagaraj Nandini Chauhan Dr. Trent W. Franks Dr. Benjamin Bardiaux Dr. Michael Habeck Dr. Marcella Orwick‐Rydmark Prof. Dirk Linke Dr. Barth‐J. van Rossum 《Angewandte Chemie (International ed. in English)》2015,54(43):12602-12606
MAS‐NMR was used to study the structure and dynamics at ambient temperatures of the membrane‐anchor domain of YadA (YadA‐M) in a pellet of the outer membrane of E. coli in which it was expressed. YadA is an adhesin from the pathogen Yersinia enterocolitica that is involved in interactions with the host cell, and it is a model protein for studying the autotransport process. Existing assignments were sucessfully transferred to a large part of the YadA‐M protein in the E. coli lipid environment by using 13C‐13C DARR and PDSD spectra at different mixing times. The chemical shifts in most regions of YadA‐M are unchanged relative to those in microcrystalline YadA‐M preparations from which a structure has previously been solved, including the ASSA region that is proposed to be involved in transition‐state hairpin formation for transport of the soluble domain. Comparisons of the dynamics between the microcrystalline and membrane‐embedded samples indicate greater flexibility of the ASSA region in the outer‐membrane preparation at physiological temperatures. This study will pave the way towards MAS‐NMR structure determination of membrane proteins, and a better understanding of functionally important dynamic residues in native membrane environments. 相似文献
16.
María Yolanda Ríos M. Ángeles Ramírez‐Cisneros Ismael León‐Rivera Samuel Estrada‐Soto Gabriel Navarrete‐Vázquez A. Berenice Aguilar‐Guadarrama 《Magnetic resonance in chemistry : MRC》2012,50(4):329-331
Complete 1H and 13C NMR chemical shift assignments for 3,4‐seco‐lup‐20(29)‐en‐3‐oic acid ( 1 ) have been established by means of two‐dimensional COSY, HSQC, HMBC and NOESY spectroscopic experiments as well as by analysis of MS data. Compound 1 was isolated from Decatropis bicolor (Zucc.) Radlk. (Rutaceae) in addition to six coumarins and one alkaloid of known structure. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
17.
Synthesis of Isoxazole, 1, 2, 4‐Oxadiazole and (1H‐Pyrazol‐4‐yl)‐methanone Oxime Derivatives from N‐Hydroxy‐1H‐pyrazole‐4‐carbimidoyl Chloride and their Biological Activity
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Bhavanarushi Sangepu Bharath Gandu Gangagnirao Anupoju Vatsalarani Jetti 《Journal of heterocyclic chemistry》2016,53(3):754-761
Some novel isoxazole‐, 1,2,4 oxadiazole‐, and (1H‐pyrazol‐4‐yl)‐methanone oxime derivatives were synthesized from N‐hydroxy‐1H‐pyrazole‐4‐carbimidoyl chloride and the structures of all products were identified by spectral data (1H‐NMR, 13C‐NMR, IR, MS, and HRMS) and evaluated their antibacterial activity. 相似文献
18.
Yun‐Chih Lin Dr. Hung‐Lung Chou Dr. Loka Subramanyam Sarma Dr. Bing‐Joe Hwang Prof. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(40):10658-10665
Understanding the complex thermodynamic behavior of confined amphiphilic molecules in biological or mesoporous hosts requires detailed knowledge of the stacking structures. Here, we present detailed solid‐state NMR spectroscopic investigations on 1‐butanol molecules confined in the hydrophilic mesoporous SBA‐15 host. A range of NMR spectroscopic measurements comprising of 1H spin–lattice (T1), spin–spin (T2) relaxation, 13C cross‐polarization (CP), and 1H,1H two‐dimensional nuclear Overhauser enhancement spectroscopy (1H,1H 2D NOESY) with the magic angle spinning (MAS) technique as well as static wide‐line 2H NMR spectra have been used to investigate the dynamics and to observe the stacking structure of confined 1‐butanol in SBA‐15. The results suggest that not only the molecular reorientation but also the exchange motions of confined molecules of 1‐butanol are extremely restricted in the confined space of the SBA‐15 pores. The dynamics of the confined molecules of 1‐butanol imply that the 1H,1H 2D NOESY should be an appropriate technique to observe the stacking structure of confined amphiphilc molecules. This study is the first to observe that a significant part of confined 1‐butanol molecules are orientated as tilted bilayered structures on the surface of the host SBA‐15 pores in a time‐average state by solid‐state NMR spectroscopy with the 1H,1H 2D NOESY technique. 相似文献
19.
113Cd NMR Experiments Reveal an Unusual Metal Cluster in the Solution Structure of the Yeast Splicing Protein Bud31p
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Dr. Anne‐Marie M. van Roon Dr. Ji‐Chun Yang Dr. Daniel Mathieu Dr. Wolfgang Bermel Dr. Kiyoshi Nagai Dr. David Neuhaus 《Angewandte Chemie (International ed. in English)》2015,54(16):4861-4864
Establishing the binding topology of structural zinc ions in proteins is an essential part of their structure determination by NMR spectroscopy. Using 113Cd NMR experiments with 113Cd‐substituted samples is a useful approach but has previously been limited mainly to very small protein domains. Here we used 113Cd NMR spectroscopy during structure determination of Bud31p, a 157‐residue yeast protein containing an unusual Zn3Cys9 cluster, demonstrating that recent hardware developments make this approach feasible for significantly larger systems. 相似文献
20.
FlorianC. Stintzing Florian Kugler Reinhold Carle Jürgen Conrad 《Helvetica chimica acta》2006,89(5):1008-1016
Due to their inherent liability towards highly acidic conditions previously considered to be a prerequisite for data acquisition, betaxanthin structure dereplication by NMR spectroscopy has been scarcely reported and was, hitherto, exclusively based on 1H‐NMR data interpretation. Applying only slightly acidic conditions, we herein report the first 13C‐NMR data of two betaxanthins, i.e., indicaxanthin ( 1 ), isolated from yellow‐orange cactus pear fruits (Opuntia ficus‐indica [L.] Mill . cv. ‘Gialla’), and of miraxanthin V ( 2 ) from yellow Swiss chard petioles (Beta vulgaris L. ssp. cicla [L.] Alef . cv. ‘Bright Lights’), as derived by gHSQC‐ and gHMQC‐NMR experiments and inverse detection. 相似文献