scholarly journals Transmembrane exchange of fluorosugars: characterization of red cell GLUT1 kinetics using 19F NMR

2018 ◽  
Author(s):  
D Shishmarev ◽  
CQ Fontenelle ◽  
I Kuprov ◽  
B Linclau ◽  
PW Kuchel
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Membrane Transport ◽  
Glucose Transport ◽  
Transport Processes ◽  
Nmr Studies ◽  
Exchange Spectroscopy ◽  
Glucose Analogues ◽  
Kinetics Of ◽  
Nuclear Magnetic

ABSTRACTWe developed a novel approach for quantifying the equilibrium-exchange kinetics of carrier-mediated transmembrane transport of fluorinated substrates. Our method is based on an adapted kinetic theory describing the concentration dependence of the transmembrane-exchange rates of two simultaneously transported species. Using the new approach, we quantified the kinetics of membrane transport of both anomers of three monofluorinated glucose analogues in human erythrocytes (red blood cells: RBCs) using 19F nuclear magnetic resonance (NMR) exchange spectroscopy (EXSY). An inosine-based glucose-free medium was shown to promote survival and stable metabolism of RBCs over the duration of the experiments (a few hours). Earlier NMR studies only yielded the apparent rate constants and transmembrane fluxes of the anomeric species, whereas we were able to categorize the two anomers in terms of the catalytic activity (specificity constants) of the glucose transport protein GLUT1 towards them. Differences in the membrane permeability of the three glucose analogues were qualitatively interpreted in terms of local perturbations in the bonding of substrates to amino-acid residues in the active site of GLUT1. The methodology of this work will be applicable to studies of other carrier-mediated membrane transport processes, especially those with competition between simultaneously transported species. The GLUT1-specific results will apply to the design of probes of glucose transport, or inhibitors of glucose metabolism in cells including those exhibiting the Warburg effect.ABBREVIATIONSEXSYexchange spectroscopyFDGfluoro-deoxy-glucoseFDG-nn-fluoro-n- deoxy-D-glucose (n = 2, 3, 4)FIDfree induction decayGlcD-glucoseNMRnuclear magnetic resonanceRBCred blood cell

Response of 31P-nuclear magnetic resonance spectra of frog skin to variations in PCO2 and hypoxia

1983 ◽  
Vol 245 (6) ◽  
pp. F792-F800
Author(s):  
R. L. Nunnally ◽  
J. S. Stoddard ◽  
S. I. Helman ◽  
J. P. Kokko
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Epithelial Transport ◽  
Transport Processes ◽  
Nmr Studies ◽  
Nernst Potential ◽  
31P Nuclear Magnetic Resonance ◽  
Order Of Magnitude ◽  
Epithelial Sheets ◽  
Nuclear Magnetic

31P-nuclear magnetic resonance (NMR) studies were conducted on split epithelial sheets of frog skins to examine the effects of hypoxia and respiratory pH variations on various phosphate-containing intracellular substrates. Frog skins were split into epithelial sheets from which the supporting tissue was removed. Epithelial sheets in either phosphate-free Cl--Ringer or phosphate-free SO2-4-Ringer were bubbled at room temperature with 100% N2, 100% O2, 2% CO2-98% O2, 5% CO2-95% O2, and 15% CO2-85% O2. The results show that the intracellular pH (pHi) with Cl- -Ringer was 7.19 and with SO2-4-Ringer was 7.42 with extracellular pH of 7.52 when bubbled with 100% O2. These pHiS indicate that H+ concentration is at least an order of magnitude less than predicted from the previously measured Nernst potential. With exposure to increasing extracellular PCO2, there is a polynomial decrease in pHi. The pHi tended to be more alkaline in SO2-4 -Ringer, suggesting the presence of a HCO-3/Cl- exchange mechanism. The ATP concentration is critically and reversibly dependent on PO2. ADP concentrations were consistently low in well-oxygenated conditions. Variable but small quantities of phosphocreatine were detected. These studies demonstrate further the potential importance in utilizing NMR spectroscopy to examine coupling of biochemical substrates to epithelial transport processes.

scholarly journals Real-time nuclear magnetic resonance spectroscopy in the study of biomolecular kinetics and dynamics

2021 ◽  
Vol 2 (1) ◽  
pp. 291-320
Author(s):  
György Pintér ◽  
Katharina F. Hohmann ◽  
J. Tassilo Grün ◽  
Julia Wirmer-Bartoschek ◽  
Clemens Glaubitz ◽  
...  
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Resonance Spectroscopy ◽  
Signal To Noise ◽  
Nmr Studies ◽  
Time Resolved ◽  
Kinetics And Dynamics ◽  
Time Limitations ◽  
Kinetics Of ◽  
Nuclear Magnetic

Abstract. The review describes the application of nuclear magnetic resonance (NMR) spectroscopy to study kinetics of folding, refolding and aggregation of proteins, RNA and DNA. Time-resolved NMR experiments can be conducted in a reversible or an irreversible manner. In particular, irreversible folding experiments pose large requirements for (i) signal-to-noise due to the time limitations and (ii) synchronising of the refolding steps. Thus, this contribution discusses the application of methods for signal-to-noise increases, including dynamic nuclear polarisation, hyperpolarisation and photo-CIDNP for the study of time-resolved NMR studies. Further, methods are reviewed ranging from pressure and temperature jump, light induction to rapid mixing to induce rapidly non-equilibrium conditions required to initiate folding.

Nuclear magnetic resonance (NMR) studies of sintering effects on the lithium ion dynamics in Li1.5Al0.5Ti1.5(PO4)3

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Edda Winter ◽  
Philipp Seipel ◽  
Tatiana Zinkevich ◽  
Sylvio Indris ◽  
Bambar Davaasuren ◽  
...  
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Lithium Ion ◽  
Magic Angle Spinning ◽  
Spin Lattice Relaxation ◽  
Magic Angle ◽  
Nmr Studies ◽  
Lithium Ions ◽  
Jump Dynamics ◽  
Nuclear Magnetic

Abstract Various nuclear magnetic resonance (NMR) methods are combined to study the structure and dynamics of Li1.5Al0.5Ti1.5(PO4)3 (LATP) samples, which were obtained from sintering at various temperatures between 650 and 900 °C. 6Li, 27Al, and 31P magic angle spinning (MAS) NMR spectra show that LATP crystallites are better defined for higher calcination temperatures. Analysis of 7Li spin-lattice relaxation and line-shape changes indicates the existence of two species of lithium ions with clearly distinguishable jump dynamics, which can be attributed to crystalline and amorphous sample regions, respectively. An increase of the sintering temperature leads to higher fractions of the fast lithium species with respect to the slow one, but hardly affects the jump dynamics in either of the phases. Specifically, the fast and slow lithium ions show jumps in the nanoseconds regime near 300 and 700 K, respectively. The activation energy of the hopping motion in the LATP crystallites amounts to ca. 0.26 eV. 7Li field-gradient diffusometry reveals that the long-range ion migration is limited by the sample regions featuring slow transport. The high spatial resolution available from the high static field gradients of our setup allows the observation of the lithium ion diffusion inside the small (<100 nm) LATP crystallites, yielding a high self-diffusion coefficient of D = 2 × 10−12 m2/s at room temperature.

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