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Calcium Metabolism in Enzymatically Dissociated Rat Heart Cells and in Intact Perfused Ferret Hearts
Published in Samuel Sideman, Rafael Beyar, Analysis and Simulation of the Cardiac System — Ischemia, 2020
Eduardo Marban, Shawn W. Robinson, W. Gil Wier, Masafumi Kitakaze, Martin M. Pike, David T. Yue, V. P. Chacko
19F NMR spectra were obtained on a Bruker® AM-360 FT NMR spectrometer equipped with an 8.5-T/89-mm superconducting magnet (19F resonance frequency of 338.86 MHz) and operated in the pulsed Fourier transform mode. The hearts were placed into a 25-mm-diameter NMR tube and lowered into the probe. All chemical shifts were referenced with respect to the 6F-Trp signal, assigned to 0 ppm.
Adulteration of Essential Oils
Published in K. Hüsnü Can Başer, Gerhard Buchbauer, Handbook of Essential Oils, 2020
Another useful method to validate the identity of an EO offers the spectroscopy of the magnetic properties of 13C nuclei. 13C NMR spectroscopy is a very useful technique regularly used to elucidate the structure of individual substances and has been applied by Kubeczka and Formácek (2002) to a large number of essential oils and individual reference compounds. Even though it is not very common to apply this technique to substance mixtures, as it is with an EO, the spectrum of a genuine oil is very distinct and characterized by the chemical shifts, signal multiplicities, and intensities of all components. Functional groups can be identified by chemical shifts and provide information on chemical structures of individual substances within the oil. No separation of the oil into its components is necessary, and therefore, the approach is simply measuring a solution of the oil in an NMR tube and comparing the spectrum with literature data or reference oils and compounds. Unfortunately NMR instruments are rarely found in traditional analytical laboratories, and thus, this method has not gained the significance in the field of EO analysis it deserves.
Gel Dosimetry
Published in Gad Shani, Radiation Dosimetry, 2017
Preparation of the agarose gels was as follows: agarose powder, Sigma Chemicals, type VII, was dissolved in triple-distilled water, then boiled to obtain a clear solution. It was subsequently oxygenated by bubbling the gas through it for 30 min and allowed to cool to 36°C before the Fricke solution was added. All steps after boiling were conducted under constant stirring. Volumes of about 70 μΐ were then poured into 5-rnm-diameter NMR tubes and allowed to gel at room temperature. The final concentrations were 1.5-mM ferrous ammonium sulphate, 1-mM sodium chloride, 50-mM sulphuric acid, and 1% agarose by weight. [12]
Correlated analytical and functional evaluation of higher order structure perturbations from oxidation of NISTmAb
Published in mAbs, 2023
Tsega L. Solomon, Frank Delaglio, John P. Giddens, John P. Marino, Yihua Bruce Yu, Marc B. Taraban, Robert G. Brinson
NMR samples were prepared from the 600 μL oxidation quenched aliquot that were thawed on the day of data collection and supplemented with 3% D2O and 150 M deuterated 3-(trimethylsilyl) propane-1-sulfonate (DSS-d6) (Sigma Aldrich). Samples were loaded into 5 mm standard NMR tubes for data acquisition. NMR experiments were measured at 50°C on a Bruker Avance III 600 MHz spectrometer equipped with a triple resonance cryogenetically cooled TCI probe and z-axis axis gradient system. 2D NMR data were recorded using a gradient-selected, sensitivity enhanced 1H- 13C gHSQC experiment with a recycle delay of 1.5 s.49 Data were collected with 64 scans and 128 increments and acquisition times of 100 ms and 14 ms in the direct and indirect dimension, respectively. Spectral window of 14 and 30 ppm, corresponding to a total data matrix of 1682 × 128 total points. Five replicate experiments were collected for each oxidation time point aliquot over the course of 18.5 h. Each experiment took approximately 3.7 h.
Stability of a high-concentration monoclonal antibody solution produced by liquid–liquid phase separation
Published in mAbs, 2021
Jack E. Bramham, Stephanie A. Davies, Adrian Podmore, Alexander P. Golovanov
NMR experiments were acquired using a Bruker 800 MHz Avance III spectrometer equipped with 5 mm TCI cryoprobe and variable temperature control unit. Sample temperature was calibrated against a standard methanol sample and verified with an external thermocouple placed in a sample tube in the probe. NMR samples (400 µL) were prepared in 5 mm NMR tubes (541-PP-7, Wilmad) with a coaxial insert (50 mm stem, Wilmad) filled with 2H2O to provide for external lock without sample adulteration. For variable temperature experiments, samples were left to equilibrate for 30 minutes upon reaching the desired temperate, with automated tuning, shimming and pulse calibration conducted following equilibration. For NMR analysis of mAbs after LLPS, lean fractions were assessed neat, whilst dense fractions were assessed neat or after dilution to lean phase concentration (10 mg/mL) with buffer containing 75 mM NaCl.
Unveiling the interaction profile of rosmarinic acid and its bioactive substructures with serum albumin
Published in Journal of Enzyme Inhibition and Medicinal Chemistry, 2020
Christina Papaemmanouil, Maria V. Chatziathanasiadou, Christos Chatzigiannis, Eleni Chontzopoulou, Thomas Mavromoustakos, Simona Golic Grdadolnik, Andreas G. Tzakos
The additional tr-NOESY experiments were recorded on Agilent Technologies DD2 600 MHz and VNMRS 800 MHz Spectrometers (NMR Centre, National Institute of Chemistry, Slovenia), using a cryoprobe, at 25 °C. The stock solutions for the ligands rosmarinic acid, caffeic acid and salvianic acid, as well as a stock solution of BSA were prepared in buffer 100% D2O, containing 10 mM Tris (98% d11). The pH was adjusted to 7.4, with the addition of DCl or NaOD. The NMR samples were prepared in an NMR tube, of 600 μL total volume. The ligand concentration was 2 mM, while the protein concentration was 20 μM, leading to a total ligand: protein ratio of 100:1. The tr-NOESY spectrum of rosmarinic acid was acquired at 600 MHz with 8192 data points in t2, 128 complex points in t1, spectral width of 4807 Hz, 32 scans, mixing time of 350 ms and relaxation delay of 1.5 s. The tr-NOESY spectra of a 1:1 mixture of salvianic (2 mM) and caffeic acid (2 mM) in the presence of BSA (20 μΜ) were acquired at 800 MHz with 8192 data points on t2, 188 complex points in t1, spectral width of 8012 Hz, 64 scans, mixing time of 700 ms and a relaxation delay of 1.5 s. Spectra were zero-filled twice and apodized with a squared sine bell function shifted by π/2 in both dimensions.