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https://www.readbyqxmd.com/read/28396388/altering-the-allosteric-pathway-in-igps-suppresses-millisecond-motions-and-catalytic-activity
#1
George P Lisi, Kyle W East, Victor S Batista, J Patrick Loria
Imidazole glycerol phosphate synthase (IGPS) is a V-type allosteric enzyme, meaning that its catalytic rate is critically dependent on activation by its allosteric ligand, N'-[(5'-phosphoribulosyl)formimino]-5-aminoimidazole-4-carboxamide ribonucleotide (PRFAR). The allosteric mechanism of IGPS is reliant on millisecond conformational motions for efficient catalysis. We engineered four mutants of IGPS designed to disrupt millisecond motions and allosteric coupling to identify regions that are critical to IGPS function...
April 10, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28388495/local-diffusion-and-diffusion-t2-distribution-measurements-in-porous-media
#2
S Vashaee, B Newling, B MacMillan, F Marica, M Li, B J Balcom
Slice-selective pulsed field gradient (PFG) and PFG-T2 measurements are developed to measure spatially-resolved molecular diffusion and diffusion-T2 distributions. A spatially selective adiabatic inversion pulse was employed for slice-selection. The slice-selective pulse is able to select a coarse slice, on the order of 1cm, at an arbitrary position in the sample. The new method can be employed to characterize oil-water mixtures in porous media. The new technique has an inherent sensitivity advantage over phase encoding imaging based methods due to signal being localized from a thick slice...
May 2017: Journal of Magnetic Resonance
https://www.readbyqxmd.com/read/28379688/effects-of-doxorubicin-cisplatin-and-tamoxifen-on-the-metabolic-profile-of-human-breast-cancer-mcf-7-cells-as-determined-by-1-h-high-resolution-magic-angle-spinning-nuclear-magnetic-resonance
#3
Roberta M Maria, Wanessa F Altei, Heloisa S Selistre-de-Araujo, Luiz A Colnago
Doxorubicin (Doxo), cisplatin (Cis), and tamoxifen (Tamo) are part of many chemotherapeutic regimens. However, there have been limited studies of the way metabolism in breast cancer is affected by chemotherapy. We studied, through (1)H high-resolution magic angle spinning nuclear magnetic resonance (HR-MAS NMR) spectroscopy, the metabolic profile of human breast cancer MCF-7 control (Con) cells as well as MCF-7 cells treated with Tamo, Cis, and Doxo. (1)H HR-MAS NMR single-pulse spectra evidenced signals from the cell compounds, including fatty acids (membranes), water-soluble proteins, and metabolites...
April 12, 2017: Biochemistry
https://www.readbyqxmd.com/read/28351813/1d-and-2d-diffusion-pore-imaging-on-a-preclinical-mr-system-using-adaptive-rephasing-feasibility-and-pulse-sequence-comparison
#4
Marco Bertleff, Sebastian Domsch, Frederik B Laun, Tristan A Kuder, Lothar R Schad
Diffusion pore imaging (DPI) has recently been proposed as a means to acquire images of the average pore shape in an image voxel or region of interest. The highly asymmetric gradient scheme of its sequence makes it substantially demanding in terms of the hardware of the NMR system. The aim of this work is to show the feasibility of DPI on a preclinical 9.4T animal scanner. Using water-filled capillaries with an inner radius of 10μm, four different variants of the DPI sequence were compared in 1D and 2D measurements...
May 2017: Journal of Magnetic Resonance
https://www.readbyqxmd.com/read/28345344/unravelling-and-quantifying-the-nmr-invisible-metabolites-interacting-with-human-serum-albumin-by-binding-competition-and-t2-relaxation-based-decomposition-analysis
#5
Ruben Barrilero, Noelia Ramirez, Joan Carles Vallvé, Delia Taverner, Rocío Fuertes, Núria Amigó, Xavier Correig
Quantitative profiling of low-molecular-weight metabolites (LMWM) by 1H-NMR is routinely used in high-throughput serum metabolomics. First, the protein background is attenuated using a T2 filter, then the LMWM signals are resolved by line-shape fitting. However, protein binding modifies the motional properties of LMWM and their signal partially attenuates with the T2 filter, along with the protein background. Consequently, the quantified LMWM signal does not reflect the total concentration in serum but the non-binding part...
March 27, 2017: Journal of Proteome Research
https://www.readbyqxmd.com/read/28306342/nmr-based-plasma-metabolomic-discrimination-for-male-fertility-assessment-of-rats-treated-with-eurycoma-longifolia-extracts
#6
Forough Ebrahimi, Baharudin Ibrahim, Chin-Hoe Teh, Vikneswaran Murugaiyah, Kit-Lam Chan
Male infertility is one of the leading causes of infertility which affects many couples worldwide. Semen analysis is a routine examination of male fertility status which is usually performed on semen samples obtained through masturbation that may be inconvenient to patients. Eurycoma longifolia (Tongkat Ali, TA), native to Malaysia, has been traditionally used as a remedy to boost male fertility. In our recent studies in rats, upon the administration of high-quassinoid content extracts of TA including TA water (TAW), quassinoid-rich TA (TAQR) extracts, and a low-quassinoid content extract including quassinoid-poor TA (TAQP) extract, sperm count (SC) increased in TAW- and TAQR-treated rats when compared to the TAQP-treated and control groups...
June 2017: Systems Biology in Reproductive Medicine
https://www.readbyqxmd.com/read/28294621/quantification-of-metabolites-by-nmr-spectroscopy-in-the-presence-of-protein
#7
Jens Wallmeier, Claudia Samol, Lisa Ellmann, Helena U Zacharias, Franziska C Vogl, Muriel Garcia, Katja Dettmer, Peter J Oefner, Wolfram Gronwald
The high reliability of NMR spectroscopy makes it an ideal tool for large-scale metabolomic studies. However, the complexity of biofluids and, in particular, the presence of macromolecules poses a significant challenge. Ultrafiltration and protein precipitation are established means of deproteinization and recovery of free or total metabolite content, but neither is ever complete. In addition, aside from cost and labor, all deproteinization methods constitute an additional source of experimental variation. The Carr-Purcell-Meiboom-Gill (CPMG) echo-train acquisition of NMR spectra obviates the need for prior deproteinization by attenuating signals from macromolecules, but concentration values of metabolites measured in blood plasma will not necessarily reflect total or free metabolite content...
March 24, 2017: Journal of Proteome Research
https://www.readbyqxmd.com/read/28216958/-1-h-nmr-based-serum-metabolomics-reveals-erythromycin-induced-liver-toxicity-in-albino-wistar-rats
#8
Atul Rawat, Durgesh Dubey, Anupam Guleria, Umesh Kumar, Amit K Keshari, Swati Chaturvedi, Anand Prakash, Sudipta Saha, Dinesh Kumar
INTRODUCTION: Erythromycin (ERY) is known to induce hepatic toxicity which mimics other liver diseases. Thus, ERY is often used to produce experimental models of drug-induced liver-toxicity. The serum metabolic profiles can be used to evaluate the liver-toxicity and to further improve the understanding of underlying mechanism. OBJECTIVE: To establish the serum metabolic patterns of Erythromycin induced hepatotoxicity in albino wistar rats using (1)H NMR based serum metabolomics...
October 2016: Journal of Pharmacy & Bioallied Sciences
https://www.readbyqxmd.com/read/28161394/magic-angle-effect-plays-a-major-role-in-both-t1rho-and-t2-relaxation-in-articular-cartilage
#9
H Shao, C Pauli, S Li, Y Ma, A S Tadros, A Kavanaugh, E Y Chang, G Tang, J Du
PURPOSE: To investigate the effect of sample orientation on T1rho and T2 values of articular cartilage in histologically confirmed normal and abnormal regions using a whole-body 3T scanner. MATERIALS AND METHODS: Eight human cadaveric patellae were evaluated using a 2D CPMG sequence for T2 measurement as well as a 2D spin-locking prepared spiral sequence and a 3D magnetization-prepared angle-modulated partitioned-k-space spoiled gradient echo snapshots (3D MAPSS) sequence for T1rho measurement...
February 1, 2017: Osteoarthritis and Cartilage
https://www.readbyqxmd.com/read/28130009/practical-considerations-for-the-acquisition-of-ultra-wideline-14-n-nmr-spectra
#10
Stanislav L Veinberg, Austin W Lindquist, Michael J Jaroszewicz, Robert W Schurko
Several considerations for the acquisition, processing, and analysis of high quality ultra-wideline (UW) (14)N solid-state NMR (SSNMR) powder patterns under static conditions are discussed. It is shown that the (14)N quadrupolar parameters may be determined accurately using the frequencies of only two discontinuities in (14)N NMR powder patterns that are dominated by the first-order quadrupolar interaction, thereby eliminating the need for the acquisition of the entire pattern and concomitantly reducing experimental time...
December 21, 2016: Solid State Nuclear Magnetic Resonance
https://www.readbyqxmd.com/read/28110117/an-adaptive-method-for-determining-an-acquisition-parameter-t0-in-a-modified-cpmg-sequence
#11
Donghui Xing, Yiren Fan, Jianfei Hao, Xinmin Ge, Chaoliu Li, Yufeng Xiao, Fei Wu
The modified CPMG (Carr-Purcell-Meiboom-Gill) pulse sequence is a common sequence used for measuring the internal magnetic field gradient distribution of formation rocks, for which t0 (the duration of the first window) is a key acquisition parameter. In order to obtain the optimal t0, an adaptive method is proposed in this paper. By studying the factors influencing discriminant factor σ and its variation trend using T2-G forward numerical simulation, it is found that the optimal t0 corresponds to the maximum value of σ...
January 9, 2017: Journal of Magnetic Resonance
https://www.readbyqxmd.com/read/28052669/self-assembly-of-human-profilin-1-detected-by-carr-purcell-meiboom-gill-nuclear-magnetic-resonance-cpmg-nmr-spectroscopy
#12
Enrico Rennella, Ashok Sekhar, Lewis E Kay
Protein oligomerization in the cell has important implications for both health and disease, and an understanding of the mechanisms by which proteins can self-associate is, therefore, of critical interest. Initial stages of the oligomerization process can be hard to detect, as they often involve the formation of sparsely populated and transient states that are difficult to characterize by standard biophysical approaches. Using relaxation dispersion nuclear magnetic resonance spectroscopy, we study the oligomerization of human profilin-1, a protein that regulates the polymerization of actin...
January 20, 2017: Biochemistry
https://www.readbyqxmd.com/read/28049727/allosteric-transmission-along-a-loosely-structured-backbone-allows-a-cardiac-troponin-c-mutant-to-function-with-only-one-ca-2-ion
#13
Mayra de A Marques, Jose Renato Pinto, Adolfo H Moraes, Anwar Iqbal, Mariana T Q de Magalhães, Jamila Monteiro, Murilo M Pedrote, Martha M Sorenson, Jerson L Silva, Guilherme A P de Oliveira
Hypertrophic cardiomyopathy (HCM) is one of the most common cardiomyopathies and a major cause of sudden death in young athletes. The Ca(2+) sensor of the sarcomere, cardiac troponin C (cTnC), plays an important role in regulating muscle contraction. Although several cardiomyopathy-causing mutations have been identified in cTnC, the limited information about their structural defects has been mapped to the HCM phenotype. Here, we used high-resolution electron-spray ionization mass spectrometry (ESI-MS), Carr-Purcell-Meiboom-Gill relaxation dispersion (CPMG-RD), and affinity measurements of cTnC for the thin filament in reconstituted papillary muscles to provide evidence of an allosteric mechanism in mutant cTnC that may play a role to the HCM phenotype...
February 10, 2017: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/28024258/phase-incremented-echo-train-acquisition-applied-to-magnetic-resonance-pore-imaging
#14
S A Hertel, P Galvosas
Efficient phase cycling schemes remain a challenge for NMR techniques if the pulse sequences involve a large number of rf-pulses. Especially complex is the Carr Purcell Meiboom Gill (CPMG) pulse sequence where the number of rf-pulses can range from hundreds to several thousands. Our recent implementation of Magnetic Resonance Pore Imaging (MRPI) is based on a CPMG rf-pulse sequence in order to refocus the effect of internal gradients inherent in porous media. While the spin dynamics for spin-1/2 systems in CPMG like experiments are well understood it is still not straight forward to separate the desired pathway from the spectrum of unwanted coherence pathways...
December 16, 2016: Journal of Magnetic Resonance
https://www.readbyqxmd.com/read/27993533/transverse-water-relaxation-in-whole-blood-and-erythrocytes-at-3t-7t-9-4t-11-7t-and-16-4t-determination-of-intracellular-hemoglobin-and-extracellular-albumin-relaxivities
#15
Ksenija Grgac, Wenbo Li, Alan Huang, Qin Qin, Peter C M van Zijl
Blood is a physiological substance with multiple water compartments, which contain water-binding proteins such as hemoglobin in erythrocytes and albumin in plasma. Knowing the water transverse (R2) relaxation rates from these different blood compartments is a prerequisite for quantifying the blood oxygenation level-dependent (BOLD) effect. Here, we report the Carr-Purcell-Meiboom-Gill (CPMG) based transverse (R2CPMG) relaxation rates of water in bovine blood samples circulated in a perfusion system at physiological temperature in order to mimic blood perfusion in humans...
May 2017: Magnetic Resonance Imaging
https://www.readbyqxmd.com/read/27966496/recent-excitements-in-protein-nmr-large-proteins-and-biologically-relevant-dynamics
#16
REVIEW
Sai Chaitanya Chiliveri, Mandar V Deshmukh
The advent of Transverse Relaxation Optimized SpectroscopY (TROSY) and perdeuteration allowed biomolecular NMR spectroscopists to overcome the size limitation barrier (approx. 20 kDa) in de novo structure determination of proteins. The utility of these techniques was immediately demonstrated on large proteins and protein complexes (e.g. GroELGroES, ClpP protease, Hsp90-p53, 20S proteasome, etc.). Further, recent methodological developments such as Residual Dipolar Couplings and Paramagnetic Relaxation Enhancement allowed accurate measurement of long-range structural restraints...
December 2016: Journal of Biosciences
https://www.readbyqxmd.com/read/27936313/knight-shift-in-13-c%C3%A2-nmr-resonances-confirms-the-coordination-of-n-heterocyclic-carbene-ligands-to-water-soluble-palladium-nanoparticles
#17
Juan M Asensio, Simon Tricard, Yannick Coppel, Román Andrés, Bruno Chaudret, Ernesto de Jesús
The coordination of N-heterocyclic carbene (NHC) ligands to the surface of 3.7 nm palladium nanoparticles (PdNPs) can be unambiguously established by observation of Knight shift (KS) in the (13) C resonance of the carbenic carbon. In order to validate this coordination, PdNPs with sizes ranging from 1.3 to 4.8 nm were prepared by thermal decomposition or reduction with CO of a dimethyl NHC Pd(II) complex. NMR studies after (13) CO adsorption established that the KS shifts the (13) C resonances of the chemisorbed molecules several hundreds of ppm to high frequencies only when the particle exceeds a critical size of around 2 nm...
December 9, 2016: Angewandte Chemie
https://www.readbyqxmd.com/read/27860024/capturing-excited-states-in-the-fast-intermediate-exchange-limit-in-biological-systems-using-1-h%C3%A2-nmr-spectroscopy
#18
Emilie Steiner, Judith Schlagnitweit, Patrik Lundström, Katja Petzold
Changes in molecular structure are essential for the function of biomolecules. Characterization of these structural fluctuations can illuminate alternative states and help in correlating structure to function. NMR relaxation dispersion (RD) is currently the only method for detecting these alternative, high-energy states. In this study, we present a versatile (1) H R1ρ RD experiment that not only extends the exchange timescales at least three times beyond the rate limits of (13) C/(15) N R1ρ and ten times for CPMG experiments, but also makes use of easily accessible probes, thus allowing a general description of biologically important excited states...
December 19, 2016: Angewandte Chemie
https://www.readbyqxmd.com/read/27810802/body-diffusion-weighted-imaging-using-non-cpmg-fast-spin-echo
#19
Eric K Gibbons, Patrick Le Roux, Shreyas S Vasanawala, John M Pauly, Adam B Kerr
SS-FSE is a fast technique that does not suffer from off-resonance distortions to the degree that EPI does. Unlike EPI, SS-FSE is ill-suited to diffusion weighted imaging (DWI) due to the Carr-Purcell-Meiboom-Geill (CPMG) condition. Non-CPMG phase cycling does accommodate SS-FSE and DWI but places constraints on reconstruction, which are resolved here through parallel imaging. Additionally, improved echo stability can be achieved by using short duration and highly selective DIVERSE radiofrequency pulses. Here, signal-to-noise ratio (SNR) comparisons between EPI and nCPMG SS-FSE acquisitions and reconstruction techniques give similar values...
February 2017: IEEE Transactions on Medical Imaging
https://www.readbyqxmd.com/read/27809381/stability-and-sensitivity-of-water-t2-obtained-with-ideal-cpmg-in-healthy-and-fat-infiltrated-skeletal-muscle
#20
Christopher D J Sinclair, Jasper M Morrow, Robert L Janiczek, Matthew R B Evans, Elham Rawah, Sachit Shah, Michael G Hanna, Mary M Reilly, Tarek A Yousry, John S Thornton
Quantifying muscle water T2 (T2 -water) independently of intramuscular fat content is essential in establishing T2 -water as an outcome measure for imminent new therapy trials in neuromuscular diseases. IDEAL-CPMG combines chemical shift fat-water separation with T2 relaxometry to obtain such a measure. Here we evaluate the reproducibility and B1 sensitivity of IDEAL-CPMG T2 -water and fat fraction (f.f.) values in healthy subjects, and demonstrate the potential of the method to quantify T2 -water variation in diseased muscle displaying varying degrees of fatty infiltration...
December 2016: NMR in Biomedicine
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