The cellular interior contains macromolecules at concentrations exceeding 300 mg/mL and volume occupancies of 30%. Until recently, however, most protein studies were performed in vitro and in dilute solutions. In-cell NMR spectroscopy provides a means to gain atomiclevel data noninvasively in the cellular environment. Although in-cell NMR has recently undergone significant advances, it is still in its infancy. Here, we review the limitations and potential pitfalls of in-cell NMR and recent advances in the field.

The design of an integrated gradient-field/frequency lock-shim system for NMR spectrometer is presented. The integrated architecture is realized by combining embedded ethernet, field programmable gate array (FPGA), external memory interface (EMI), controller area network (CAN) bus and high-speed serial bus technologies, making the system compact and reliable. The system consists of three parts: (1) the field/frequency lock subsystem which ensures the stability of the magnetic field, (2) the shim subsystem which guarantees the consistency of the magnetic field, and (3) the gradient amplifier which generates the gradient field pulse. Due to its flexibility, the design can easily be adapted for different NMR spectrometers. The feasibility of the integrated system is illustrated by  tests of the shim, lock and gradient outputs on a 11.7 T NMR spectrometer.

A control interface for magnetic resonance imaging (MRI) spectrometer was presented. The control interface connects the host computer and the MRI spectrometer, which has the following functionalities: supervising the operation of pulse programmer and receiver, using direct memory access (DMA) and transferring the processed data via Gigabit Ethernet transmission. The real-time interaction between the host PC and the spectrometer is achieved through two Ethernet links. Its scalable hardware consists of a computer-on-module (COM) and a carrier. The COM possesses a high-performance CPU, which has both Cotex-A8 and DSP sub-units. The software, including Linux kernel, drivers and a console server, was developed for the board. Tests show that this scalable structure can achieve high data processing & transmission speed. With features such as low-cost and highly-integrated characteristics, the control interface is suitable for most MRI spectrometers, especially for portable ones.

Effects of gradient field linearity on the quality of images acquired on a permanent magnet mini-magnetic resonance imager were analyzed by theoretical analyses and numerical simulation. It was shown that gradient field with high linearity is a prerequisite to obtain high-quality images of small animals, such as mice, on permanent magnet, low field strength micro-magnetic resonance imagers. The gradient field linearity specification reported in the literature is too low to acquired high-quality mouse images. The image quality could not be improved by software compensation methods. The newly developed gradient field coil with high linear property and our independent intellectual property was also presented. The optimized gradient coil has been installed on our instrument, and yielded a better quality image.

¹H  and ¹³C NMR spectroscopy was carried out to investigate the chiral recognition of trans-4-hydroxyproline using water-soluble chiral lanthanide shift reagent Sm-pdta. When complexed with Smpdta, most signals in the ¹H  and ¹³C NMR spectra of trans-4-hydroxy-L-proline and trans-4-hydroxy-D-proline were shifted, leading to separation of the signals from the two enantiomers. The results showed that Sm-pdta is an effective reagent for chiral recognition of trans-4-hydroxyproline.

Prediction of chemical shifts using quantum chemical calculations is a useful tool for NMR spectra assignment. In this work, the protons chemical shifts of Valsartan dissolved in sodium dodecyl sulfate (SDS) micelle were calculated and compared with those obtained from NMR experiments. The computational results, especially those obtained with the ONIOM method, could distinguish the two conformations dissolved in the SDS micelle, and the theoretical values of chemical shifts are in reasonable agreement with those obtained with NMR experiments. Our study showed that in the calculations of chemical shifts of complex system, the environment should be considered in the theoretical model.

In magnetic resonance imaging, spike noise in the K-space will degrade the quality of the reconstructed images severely. We proposed a new approach to locate and remove spike noises based on the information in the background region. Firstly, one-dimensional discrete Fourier transform (DFT) is applied to K-space data along the k_x and k_y direction respectively to acquire two half transformed datasets. Then background in these two datasets are extracted and analyzed to locate and remove the spike noise. By experiments on simulated and real data, the proposed approach was proven to be able to remove certain kinds of spike noises effectively. Compared with the previous algorithms, this approach has the unique advantage in that it can deal with the cases in which consecutive rows of K-space data are contaminated with spike noises.

A water-fat separation magnetic resonance image (MRI) method based on inversion recovery technique, aiming to obtain water-only and fatonly images, was introduced. Base on different T₁ relaxation time of water and fat, two different inversion recovery time (T_I) was used to acquire two sets of MRI images with different water-fat signal contribution. With the images having different water and fat contributions, the water-only and fat-only images can be calculated by solving equations describing the relationship between the total signal intensity and the water/fat signal intensities. It was demonstrated that this method can be used to separate water and fat signals correctly and avoid the water-fat swap artifact that occurred sporadically in conventional Dixon method. With this method, no complex phase correction was needed, making the computation more simple and stable.

The host-guest chemistry of systems containing fasudil hydrochloride (FSDE) and cucurbit[n]uril (CB[n], n=7, 8) was investigated by NMR, ESI-MS, UV-Vis and IR spectroscopy. The experiment results indicated that the guest fasudil hydrochloride and CB[n] (n=7, 8) host could form a stable 1∶1 (molar ratio) inclusion complex, in which the positions of CB[7] and CB[8] were different because of the sizes of their cavities. The inclusion constant of fasudil hydrochloride with CB\[7\] and CB[8] was 2 524 L/mol and 1 216 L/mol, respectively. The binding constant was in the range of 200  L/mol~10 000 L/mol, indicating that CB[7] and CB[8] could be used as possible slow-released agents.

Faropenem sodium is a new and orally administered β-lactam antibiotic. The spectral data of faropenem sodium were reported, including UV, IR, MS, EA, TGA and NMR data. The NMR data included one-dimensional ¹H  and ¹³C NMR spectra and two-dimensional spectra including ¹H-¹H COSY, HSQC and HMBC. The NMR and IR signals were assigned. The molecular structure of faropenem sodium was determined.

An important intermediate of D-A-D polyfluorene derivative, 2,7-bis(4,4,5,5-tetramethyl-1,3,2-dioxaboralan-2-yl)-9,9-dioctylfluorene, was synthesized from Suzuki coupling polymerization. One- and two-dimensional NMR techniques (i.e., ¹H NMR, ¹³C NMR, DEPT, ¹H-¹H COSY, HMQC and HMBC) were used to assign the proton and carbon chemical shifts and to elucidate the structure of the compound.

The infrared spectrum, ultraviolet spectrum, nuclear magnetic resonance spectra and mass spectra of aspoxicillin, a semi-synthetic penicillin, were collected and interpreted. All the NMR signals were assigned. Based on the mass spectral data, the possible fragmentation pathways were discussed. The infrared spectrum was used to analyze the types of vibration of the functional groups in this compound. The structure of the compound was determined.

A new compound, N-phenyl-2-({5-[(2-(phenoxymethyl)-benzimidazol-1-yl)methyl]-1, 3, 4-oxadiazol-2-yl}thio) acetamide (3), was synthesized by the reaction of 5-{[2-(phenoxymethyl)-benzimidazol-1-yl]methyl}-2-thiol-1,3, 4-oxadiazole (2) with N-phenyl-2-chloro-acetamide. The compound 2 was obtained by the reaction of the hydrazide (1) with carbon disulfide in the presence of absolute ethanol and potassium hydroxide. The structure of the new compound 3 was determined by elemental analysis, IR and NMR techniques. The ¹H  and ¹³C NMR signals of the two isomers (trans and cis) of compound 3 were assigned using 2D NMR techniques. The corresponding coupling constants and the tautomeric ratios of isomers were calculated. The ratio of the dominant trans isomer was 64.5%, while the cis isomer was 35.5%.

Human MRG15 is a transcription factor that plays an important role in embryonic development, cell proliferation and senescence. The MRG15 chromo domain can interact with methylated Lys36 of histone H3. In this study, the assignment of amino acids of MRG15 chromo domain was done using solution NMR spectroscopy. The interaction between MRG15 chromo domain and H3K36me3 peptide was studied by the chemical shift perturbation approach. The binding sites (i.e., H21，Y46，W49 and W53) and dissociation constants (~1 mmol/L) were determined. These results provide give insight on the interaction between MRG15 chromo domain and histone H3 at molecular level.

Measurement of spin relaxation times is a useful tool for studying molecular dynamics in solids. It has been applied in the studies of molecular motions of sugars, amino acids, vitamins, adrenalin and testosterone, et al. Recently, it is also used in the studies of molecular dynamics associated with polymorphic phase transitions and structural dependence of molecular dynamics in small organic metabolites. This paper gives an introduction of spin relaxation times and their measurements with the emphasis on its application in the studies of molecular dynamics of sugars, amino acids and their derivatives.

¹⁹F nucleus has unique properties, such as that it is a 1/2 spin; natural abundance is 100%, having comparable sensitivity as ¹H; chemical shift dispersion is large and ultra sensitive to the environment; most biological samples do not contain ¹⁹F, such that there is no interference background signal, etc. These properties make ¹⁹F NMR an attractive approach to study biological systems. ¹⁹F NMR has wide applications in magnetic resonance imaging, pharmacology chemistry and studies of biomacromolecules. There are many reviews on these topics. Here we will focus on the applications of ¹⁹F NMR in protein studies, including ¹⁹F labeling methods, protein structure and dynamics characterization, protein folding, protein-drug interactions and in-cell protein NMR.

《波谱学杂志》是国内磁共振波谱领域唯一的学术期刊，  由中国物理学会波谱学专业委员会和中国科学院武汉物理与数学研究所共同主办，  创刊于1983年6月，  中英文混合刊，  国内外公开发行.

刊登内容：磁共振波谱方面的文章， 包括核磁共振（NMR）， 磁共振成像（MRI）， 核电四极矩共振（NQR）， 电子自旋共振（ESR）， 光磁共振（LMR）、 微波波段原子频率标准等方面的基础与应用基础研究.

读者对象： 从事磁共振和原子频率标准研究的科研人员， 化学、 化工、 生物、 医药等企事业单位科研和测试分析人员， 大专院校相关专业的教师和研究生.

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