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Journal of Biomolecular NMR

Sven G Hyberts, Scott A Robson, Gerhard Wagner
Non-Uniform Sampling has the potential to exploit the optimal resolution of high-field NMR instruments. This is not possible in 3D and 4D NMR experiments when using traditional uniform sampling due to the long overall measurement time. Nominally, uniformly sampled time domain data acquired to a maximum evolution time tmax can be extended to high resolution via a virtual maximum evolution time t*max while extrapolating with linear prediction or iterative soft thresholding (IST). At the high resolution obtainable with extrapolation of US data, however, the accuracy of peak positions is compromised as observed when comparing inter- and intra-residue peaks in a 3D HNCA experiment...
March 22, 2017: Journal of Biomolecular NMR
Pramodh Valluruapalli, Ashok Sekhar, Tairan Yuwen, Lewis E Kay
Although Chemical Exchange Saturation Transfer (CEST) type NMR experiments have been used to study chemical exchange processes in molecules since the early 1960s, there has been renewed interest in the past several years in using this approach to study biomolecular conformational dynamics. The methodology is particularly powerful for the study of sparsely populated, transiently formed conformers that are recalcitrant to investigation using traditional biophysical tools, and it is complementary to relaxation dispersion and magnetization transfer experiments that have traditionally been used to study chemical exchange processes...
March 19, 2017: Journal of Biomolecular NMR
Qi Gao, Gordon R Chalmers, Kelley W Moremen, James H Prestegard
Sparse isotopic labeling of proteins for NMR studies using single types of amino acid ((15)N or (13)C enriched) has several advantages. Resolution is enhanced by reducing numbers of resonances for large proteins, and isotopic labeling becomes economically feasible for glycoproteins that must be expressed in mammalian cells. However, without access to the traditional triple resonance strategies that require uniform isotopic labeling, NMR assignment of crosspeaks in heteronuclear single quantum coherence (HSQC) spectra is challenging...
March 13, 2017: Journal of Biomolecular NMR
Beat Vögeli
The relaxation interference between dipole-dipole interactions of two separate spin pairs carries structural and dynamics information. In particular, when compared to individual dynamic behavior of those spin pairs, such cross-correlated relaxation (CCR) rates report on the correlation between the spin pairs. We have recently mapped out correlated motion along the backbone of the protein GB3, using CCR rates among and between consecutive H(N)-N and H(α)-C(α) dipole-dipole interactions. Here, we provide a detailed account of the measurement of the four types of CCR rates...
March 12, 2017: Journal of Biomolecular NMR
Allan M Torres, Gang Zheng, William S Price
Highly selective and efficient water signal suppression is indispensable in biomolecular 2D nuclear Overhauser effect spectroscopy (NOESY) experiments. However, the application of conventional water suppression schemes can cause a significant or complete loss of the biomolecular resonances at and around the water chemical shift (ω2). In this study, a new sequence, NOESY-WaterControl, was developed to address this issue. The new sequence was tested on lysozyme and bovine pancreatic trypsin inhibitor (BPTI), demonstrating its efficiency in both water suppression and, more excitingly, preserving water-proximate biomolecular resonances in ω2...
March 7, 2017: Journal of Biomolecular NMR
Ulrich Weininger
NMR-spectroscopy enables unique experimental studies on protein dynamics at atomic resolution. In order to obtain a full atom view on protein dynamics, and to study specific local processes like ring-flips, proton-transfer, or tautomerization, one has to perform studies on amino-acid side chains. A key requirement for these studies is site-selective labeling with (13)C and/or (1)H, which is achieved in the most general way by using site-selectively (13)C-enriched glucose (1- and 2-(13)C) as the carbon source in bacterial expression systems...
February 28, 2017: Journal of Biomolecular NMR
Krzysztof Kosiński, Jan Stanek, Michał J Górka, Szymon Żerko, Wiktor Koźmiński
A method for five-dimensional spectral reconstruction of non-uniformly sampled NMR data sets is proposed. It is derived from the previously published signal separation algorithm, with major alterations to avoid unfeasible processing of an entire five-dimensional spectrum. The proposed method allows credible reconstruction of spectra from as little as a few hundred data points and enables sensitive resonance detection in experiments with a high dynamic range of peak intensities. The efficiency of the method is demonstrated on two high-resolution spectra for rapid sequential assignment of intrinsically disordered proteins, namely 5D HN(CA)CONH and 5D (HACA)CON(CO)CONH...
February 28, 2017: Journal of Biomolecular NMR
Erik Walinda, Daichi Morimoto, Masahiro Shirakawa, Kenji Sugase
It is becoming increasingly apparent that proteins are not static entities and that their function often critically depends on accurate sampling of multiple conformational states in aqueous solution. Accordingly, the development of methods to study conformational states in proteins beyond their ground-state structure ("excited states") has crucial biophysical importance. Here we investigate experimental schemes for optimally probing chemical exchange processes in proteins on the micro- to millisecond timescale by (15)N R 1ρ relaxation dispersion...
February 28, 2017: Journal of Biomolecular NMR
Yong Yao, Samit Kumar Dutta, Sang Ho Park, Ratan Rai, L Miya Fujimoto, Andrey A Bobkov, Stanley J Opella, Francesca M Marassi
The outer membrane protein Ail (Adhesion invasion locus) is one of the most abundant proteins on the cell surface of Yersinia pestis during human infection. Its functions are expressed through interactions with a variety of human host proteins, and are essential for microbial virulence. Structures of Ail have been determined by X-ray diffraction and solution NMR spectroscopy, but those samples contained detergents that interfere with functionality, thus, precluding analysis of the structural basis for Ail's biological activity...
February 26, 2017: Journal of Biomolecular NMR
Abhishek Mandal, Jennifer C Boatz, Travis B Wheeler, Patrick C A van der Wel
A number of recent advances in the field of magic-angle-spinning (MAS) solid-state NMR have enabled its application to a range of biological systems of ever increasing complexity. To retain biological relevance, these samples are increasingly studied in a hydrated state. At the same time, experimental feasibility requires the sample preparation process to attain a high sample concentration within the final MAS rotor. We discuss these considerations, and how they have led to a number of different approaches to MAS NMR sample preparation...
February 22, 2017: Journal of Biomolecular NMR
Tommaso Banelli, Marco Vuano, Federico Fogolari, Andrea Fusiello, Gennaro Esposito, Alessandra Corazza
We describe a new algorithmic approach able to automatically pick and track the NMR resonances of a large number of 2D NMR spectra acquired during a stepwise variation of a physical parameter. The method has been named Trace in Track (TINT), referring to the idea that a gaussian decomposition traces peaks within the tracks recognised through 3D mathematical morphology. It is capable of determining the evolution of the chemical shifts, intensity and linewidths of each tracked peak.The performances obtained in term of track reconstruction and correct assignment on realistic synthetic spectra were high above 90% when a noise level similar to that of experimental data were considered...
February 17, 2017: Journal of Biomolecular NMR
Sophie N Koroloff, Deanna M Tesch, Emmanuel O Awosanya, Alexander A Nevzorov
Multidimensional separated local-field and spin-exchange experiments employed by oriented-sample solid-state NMR are essential for structure determination and spectroscopic assignment of membrane proteins reconstituted in macroscopically aligned lipid bilayers. However, these experiments typically require a large number of scans in order to establish interspin correlations. Here we have shown that a combination of optimized repetitive cross polarization (REP-CP) and membrane-embedded free radicals allows one to enhance the signal-to-noise ratio by factors 2...
February 15, 2017: Journal of Biomolecular NMR
Tobias Harsch, Philipp Schneider, Bärbel Kieninger, Harald Donaubauer, Hans Robert Kalbitzer
Side chain amide protons of asparagine and glutamine residues in random-coil peptides are characterized by large chemical shift differences and can be stereospecifically assigned on the basis of their chemical shift values only. The bimodal chemical shift distributions stored in the biological magnetic resonance data bank (BMRB) do not allow such an assignment. However, an analysis of the BMRB shows, that a substantial part of all stored stereospecific assignments is not correct. We show here that in most cases stereospecific assignment can also be done for folded proteins using an unbiased artificial chemical shift data base (UACSB)...
February 15, 2017: Journal of Biomolecular NMR
Tomas Miljenović, Xinying Jia, Peter Lavrencic, Bostjan Kobe, Mehdi Mobli
NMR spectroscopy is a powerful method in structural and functional analysis of macromolecules and has become particularly prevalent in studies of protein structure, function and dynamics. Unique to NMR spectroscopy is the relatively low constraints on sample preparation and the high level of control of sample conditions. Proteins can be studied in a wide range of buffer conditions, e.g. different pHs and variable temperatures, allowing studies of proteins under conditions that are closer to their native environment compared to other structural methods such as X-ray crystallography and electron microscopy...
February 10, 2017: Journal of Biomolecular NMR
Thomas Bauer, Claudio Dotta, Livia Balacescu, Julia Gath, Andreas Hunkeler, Anja Böckmann, Beat H Meier
The temperature-dependent resonance-line broadening of HET-s(218-289) in its amyloid form is investigated in the range between 110 K and 280 K. Significant differences are observed between residues in the structured hydrophobic triangular core, which are broadened the least and can be detected down to 100 K, and in the solvent-exposed parts, which are broadened the most and often disappear from the observed spectrum around 200 K. Below the freezing of the bulk water, around 273 K, the protein fibrils are still surrounded by a layer of mobile water whose thickness decreases with temperature, leading to drying out of the fibrils...
February 4, 2017: Journal of Biomolecular NMR
Albert A Smith
Software for fitting of NMR spectra in MATLAB is presented. Spectra are fitted in the frequency domain, using Fourier transformed lineshapes, which are derived using the experimental acquisition and processing parameters. This yields more accurate fits compared to common fitting methods that use Lorentzian or Gaussian functions. Furthermore, a very time-efficient algorithm for calculating and fitting spectra has been developed. The software also performs initial peak picking, followed by subsequent fitting and refinement of the peak list, by iteratively adding and removing peaks to improve the overall fit...
February 3, 2017: Journal of Biomolecular NMR
Julia M Würz, Peter Güntert
The automated identification of signals in multidimensional NMR spectra is a challenging task, complicated by signal overlap, noise, and spectral artifacts, for which no universally accepted method is available. Here, we present a new peak picking algorithm, CYPICK, that follows, as far as possible, the manual approach taken by a spectroscopist who analyzes peak patterns in contour plots of the spectrum, but is fully automated. Human visual inspection is replaced by the evaluation of geometric criteria applied to contour lines, such as local extremality, approximate circularity (after appropriate scaling of the spectrum axes), and convexity...
February 3, 2017: Journal of Biomolecular NMR
Changmiao Guo, Guangjin Hou, Xingyu Lu, Tatyana Polenova
REDOR-based experiments with simultaneous (1)H-(13)C and (1)H-(15)N dipolar dephasing are explored for investigating intermolecular protein-protein interfaces in complexes formed by a U-(13)C,(15)N-labeled protein and its natural abundance binding partner. The application of a double-REDOR filter (dREDOR) results in a complete dephasing of proton magnetization in the U-(13)C,(15)N-enriched molecule while the proton magnetization of the unlabeled binding partner is not dephased. This retained proton magnetization is then transferred across the intermolecular interface by (1)H-(13)C or (1)H-(15)N cross polarization, permitting to establish the residues of the U-(13)C,(15)N-labeled protein, which constitute the binding interface...
January 24, 2017: Journal of Biomolecular NMR
Albert A Smith, Francesco Ravotti, Emilie Testori, Riccardo Cadalbert, Matthias Ernst, Anja Böckmann, Beat H Meier
Fast magic-angle spinning and partial sample deuteration allows direct detection of (1)H in solid-state NMR, yielding significant gains in mass sensitivity. In order to further analyze the spectra, (1)H detection requires assignment of the (1)H resonances. In this work, resonance assignments of backbone H(N) and Hα are presented for HET-s(218-289) fibrils, based on the existing assignment of Cα, Cβ, C', and N resonances. The samples used are partially deuterated for higher spectral resolution, and the shifts in resonance frequencies of Cα and Cβ due to the deuterium isotope effect are investigated...
January 10, 2017: Journal of Biomolecular NMR
Ye Tian, Charles D Schwieters, Stanley J Opella, Francesca M Marassi
Structure determination of proteins by NMR is unique in its ability to measure restraints, very accurately, in environments and under conditions that closely mimic those encountered in vivo. For example, advances in solid-state NMR methods enable structure determination of membrane proteins in detergent-free lipid bilayers, and of large soluble proteins prepared by sedimentation, while parallel advances in solution NMR methods and optimization of detergent-free lipid nanodiscs are rapidly pushing the envelope of the size limit for both soluble and membrane proteins...
December 29, 2016: Journal of Biomolecular NMR
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