1
|
Romanenko K, Elliott SJ, Shubin AA, Kuchel PW. Identification of beryllium fluoride complexes in mechanically distorted gels using quadrupolar split 9Be NMR spectra resolved with solution-state selective cross-polarization. Phys Chem Chem Phys 2021; 23:16932-16941. [PMID: 34337629 DOI: 10.1039/d1cp02515e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The uniformly anisotropic media afforded by hydrogels are being increasingly exploited in analytical (structure elucidation) nuclear magnetic resonance (NMR) spectroscopy, and in studies of mechanosensitive biophysical and biochemical properties of living cells. The 9Be NMR parameters of beryllium fluoride complexes formed in aqueous solutions are sensitive markers of the anisotropic molecular environments produced by gelatin gels. The electric quadrupole moment of the 9Be nucleus (spin I = 3/2) interacts with the electric field gradient tensor in a stretched (or compressed) gel, giving rise to the splitting of peaks in 9Be NMR spectra. These are in addition to those produced by scalar coupling to the 19F nuclei. Thus, an equilibrium mixture of beryllofluoride complexes (BeF2, BeF3-, and BeF42-) in mechanically distorted gels generates an envelope of overlapping 9Be NMR multiplets. In the present work, the multiplets were dissected apart by using selective excitation of 9Be-19F cross-polarization; and the spectral components were quantified with multi-parameter line-shape decomposition, coupled with SpinDynamica simulations. The effects of gel density and Bloom number (a measure of gelatin-gel rigidity under standard conditions of sample preparation) on residual quadrupolar splittings were examined. Cross-polarization experiments revealed a bimodal distribution of residual quadrupolar coupling constants (RQC) of the BeF3- complexes. The average RQC of the dominant BeF3- population was ∼3 times larger than that of BeF42-. The secondary BeF3- population existed in a tetrahedral configuration. It was attributed to BeF3- complexes associated with negatively charged -COO- groups of the denatured collagen matrix.
Collapse
Affiliation(s)
- Konstantin Romanenko
- School of Life and Environmental Sciences, University of Sydney, Building G08, Sydney, NSW 2006, Australia.
| | | | | | | |
Collapse
|
2
|
Enhanced Ca 2+ influx in mechanically distorted erythrocytes measured with 19F nuclear magnetic resonance spectroscopy. Sci Rep 2021; 11:3749. [PMID: 33580124 PMCID: PMC7881017 DOI: 10.1038/s41598-021-83044-z] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2020] [Accepted: 01/19/2021] [Indexed: 01/30/2023] Open
Abstract
We present the first direct nuclear magnetic resonance (NMR) evidence of enhanced entry of Ca2+ ions into human erythrocytes (red blood cells; RBCs), when these cells are mechanically distorted. For this we loaded the RBCs with the fluorinated Ca2+ chelator, 1,2-bis(2-amino-5-fluorophenoxy)ethane-N,N,N',N'-tetraacetic acid (5FBAPTA), and recorded 19F NMR spectra. The RBCs were suspended in gelatin gel in a special stretching/compression apparatus. The 5FBAPTA was loaded into the cells as the tetraacetoxymethyl ester; and 13C NMR spectroscopy with [1,6-13C]D-glucose as substrate showed active glycolysis albeit at a reduced rate in cell suspensions and gels. The enhancement of Ca2+ influx is concluded to be via the mechanosensitive cation channel Piezo1. The increased rate of influx brought about by the activator of Piezo1, 2-[5-[[(2,6-dichlorophenyl)methyl]thio]-1,3,4-thiadiazol-2-yl]-pyrazine (Yoda1) supported this conclusion; while the specificity of the cation-sensing by 5FBAPTA was confirmed by using the Ca2+ ionophore, A23187.
Collapse
|
3
|
Meikle TG, Keizer DW, Babon JJ, Drummond CJ, Separovic F, Conn CE, Yao S. Chemical Exchange of Hydroxyl Groups in Lipidic Cubic Phases Characterized by NMR. J Phys Chem B 2021; 125:571-580. [PMID: 33251799 DOI: 10.1021/acs.jpcb.0c08699] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Proton transportation in proximity to the lipid bilayer membrane surface, where chemical exchange represents a primary pathway, is of significant interest in many applications including cellular energy turnover underlying ATP synthesis, transmembrane mobility, and transport. Lipidic inverse bicontinuous cubic phases (LCPs) are unique membrane structures formed via the spontaneous self-assembly of certain lipids in an aqueous environment. They feature two networks of water channels, separated by a single lipid bilayer which approximates the geometry of a triply periodic minimal surface. When composed of monoolein, the LCP bilayer features two glycerol hydroxyl groups at the lipid-water interface which undergo exchange with water. Depending on the conditions of the aqueous solution used in the formation of LCPs, both resonances of the glycerol hydroxyl groups may be observed by solution 1H NMR. In this study, PFG-NMR and 1D EXSY were employed to gain insight into chemical exchange between the monoolein hydroxyl groups and water in LCPs. Results including the relative population of hydroxyl protons in exchange with water for a number of LCPs at different hydration levels and the exchange rate constants at 35 wt % hydration are reported. Several technical aspects of PFG-NMR and EXSY-NMR for the characterization of chemical exchange in LCPs are discussed, including an alternative way to analyze PFG-NMR data of exchange systems which overcomes the inherent low sensitivity at high diffusion encoding.
Collapse
Affiliation(s)
- Thomas G Meikle
- School of Science, College of Science, Engineering and Health, RMIT University, Melbourne, VIC 3000, Australia
| | - David W Keizer
- Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Melbourne, VIC 3010, Australia
| | - Jeffrey J Babon
- The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC 3052, Australia.,Department of Medical Biology, The University of Melbourne, Melbourne, VIC 3010, Australia
| | - Calum J Drummond
- School of Science, College of Science, Engineering and Health, RMIT University, Melbourne, VIC 3000, Australia
| | - Frances Separovic
- Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Melbourne, VIC 3010, Australia.,School of Chemistry, The University of Melbourne, Melbourne, VIC 3010, Australia
| | - Charlotte E Conn
- School of Science, College of Science, Engineering and Health, RMIT University, Melbourne, VIC 3000, Australia
| | - Shenggen Yao
- Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Melbourne, VIC 3010, Australia
| |
Collapse
|
4
|
Rapid zero-trans kinetics of Cs + exchange in human erythrocytes quantified by dissolution hyperpolarized 133Cs + NMR spectroscopy. Sci Rep 2019; 9:19726. [PMID: 31873230 PMCID: PMC6928147 DOI: 10.1038/s41598-019-56250-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2019] [Accepted: 12/02/2019] [Indexed: 12/31/2022] Open
Abstract
Transmembrane flux of Cs+ (a K+ congener) was measured in human red blood cells (RBCs; erythrocytes) on the 10-s time scale. This is the first report on dissolution dynamic nuclear polarization (dDNP) nuclear magnetic resonance (NMR) spectroscopy with this nuclide in mammalian cells. Four technical developments regularized sample delivery and led to high quality NMR spectra. Cation-free media with the Piezo1 (mechanosensitive cation channel) activator yoda1 maximized the extent of membrane transport. First-order rate constants describing the fluxes were estimated using a combination of statistical methods in Mathematica, including the Markov chain Monte Carlo (MCMC) algorithm. Fluxes were in the range 4-70 μmol Cs+ (L RBC)-1 s-1; these are smaller than for urea, but comparable to glucose. Methodology and analytical procedures developed will be applicable to transmembrane cation transport studies in the presence of additional Piezo1 effectors, to other cellular systems, and potentially in vivo.
Collapse
|
5
|
Schepkin VD. Statistical tensor analysis of the MQ MR signals generated by weak quadrupole interactions. Z Med Phys 2019; 29:326-336. [PMID: 31160139 DOI: 10.1016/j.zemedi.2019.03.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2018] [Revised: 02/02/2019] [Accepted: 03/27/2019] [Indexed: 11/16/2022]
Abstract
Multiple quantum NMR signals that appear in the presence of weak quadrupole interactions were formulated using statistical tensors (Fano, 1957). The approach aimed to present a concise and a computer-based tool for a detailed analysis and modification of the MQ pulse sequences. The calculation avoids a lengthy procedure of utilizing exponential operators and, moreover, the same formulae are applicable for any interval in the TQ pulse sequence, as well as any spin value. The quantum operator algebra was implemented using "Mathematica" software (Wolfram Inc.). The results of tensor's evolutions in the TQ pulse sequence were graphically illustrated using corresponding spherical harmonics. The visualization takes into consideration the parity properties of irreducible tensors and the corresponding spherical harmonics.
Collapse
Affiliation(s)
- Victor D Schepkin
- CIMAR, National High Magnetic Field Laboratory/FSU, Tallahassee, FL, USA.
| |
Collapse
|
6
|
Bengs C, Levitt MH. SpinDynamica: Symbolic and numerical magnetic resonance in a Mathematica environment. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2018; 56:374-414. [PMID: 28809056 PMCID: PMC6001486 DOI: 10.1002/mrc.4642] [Citation(s) in RCA: 76] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2017] [Accepted: 08/03/2017] [Indexed: 05/11/2023]
Abstract
SpinDynamica is a set of Mathematica packages for performing numerical and symbolic analysis of a wide range of magnetic resonance experiments and phenomena. An overview of the SpinDynamica architecture and functionality is given, with some simple representative examples.
Collapse
Affiliation(s)
- Christian Bengs
- School of ChemistryUniversity of SouthamptonSouthamptonSO17 1BJUK
| | | |
Collapse
|
7
|
Kuchel PW, Kirk K, Shishmarev D. The NMR 'split peak effect' in cell suspensions: Historical perspective, explanation and applications. PROGRESS IN NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY 2018; 104:1-11. [PMID: 29405979 DOI: 10.1016/j.pnmrs.2017.11.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2017] [Revised: 10/31/2017] [Accepted: 11/02/2017] [Indexed: 06/07/2023]
Abstract
The physicochemical environment inside cells is distinctly different from that immediately outside. The selective exchange of ions, water and other molecules across the cell membrane, mediated by integral, membrane-embedded proteins is a hallmark of living systems. There are various methodologies available to measure the selectivity and rates (kinetics) of such exchange processes, including several that take advantage of the non-invasive nature of NMR spectroscopy. A number of solutes, including particular inorganic ions, show distinctive NMR behaviour, in which separate resonances arise from the intra- and extracellular solute populations, without the addition of shift reagents, differences in pH, or selective binding partners. This 'split peak effect/phenomenon', discovered in 1984, has become a valuable tool, used in many NMR studies of cellular behaviour and function. The explanation for the phenomenon, based on the differential hydrogen bonding of the reporter solutes to water, and the various ways in which this phenomenon has been used to investigate aspects of cellular biochemistry and physiology, are the topics of this review.
Collapse
Affiliation(s)
- Philip W Kuchel
- The University of Sydney, School of Life and Environmental Sciences, Faculty of Science, Sydney, NSW 2006, Australia.
| | - Kiaran Kirk
- Australian National University, Research School of Biology, College of Science, Canberra, ACT 2601, Australia
| | - Dmitry Shishmarev
- The University of Sydney, School of Life and Environmental Sciences, Faculty of Science, Sydney, NSW 2006, Australia; Australian National University, John Curtin School of Medical Research, College of Health and Medicine, Canberra, ACT 2601, Australia
| |
Collapse
|
8
|
Kuchel PW, Shishmarev D. Accelerating metabolism and transmembrane cation flux by distorting red blood cells. SCIENCE ADVANCES 2017; 3:eaao1016. [PMID: 29057326 PMCID: PMC5647125 DOI: 10.1126/sciadv.aao1016] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/14/2017] [Accepted: 09/21/2017] [Indexed: 06/07/2023]
Abstract
Under static conditions, mammalian red blood cells (RBCs) require a continuous supply of energy, typically via glucose, to maintain their biconcave disc shape. Mechanical distortion, in a complementary way, should lead to increased energy demand that is manifest in accelerated glycolysis. The experimental challenge in observing this phenomenon was met by reversibly and reproducibly distorting the cells and noninvasively measuring glycolytic flux. This was done with a gel-distorting device that was coupled with 13C nuclear magnetic resonance (NMR) spectroscopy. We measured [3-13C]l-lactate production from [1,6-13C]d-glucose in the RBCs suspended in gelatin gels, and up to 90% rate enhancements were recorded. Thus, for the first time, we present experiments that demonstrate the linkage of mechanical distortion to metabolic changes in whole mammalian cells. In seeking a mechanism for the linkage between shape and energy supply, we measured transmembrane cation flux with Cs+ (as a K+ congener) using 133Cs NMR spectroscopy, and the cation flux was increased up to fivefold. The postulated mechanism for these notable (in terms of whole-body energy consumption) responses is stimulation of Ca-adenosine triphosphatase by increased transmembrane flux of Ca2+ via the channel protein Piezo1 and increased glycolysis because its flux is adenosine triphosphate demand-regulated.
Collapse
|
9
|
Shishmarev D, Momot KI, Kuchel PW. Anisotropic diffusion in stretched hydrogels containing erythrocytes: evidence of cell-shape distortion recorded by PGSE NMR spectroscopy. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2017; 55:438-446. [PMID: 26914993 DOI: 10.1002/mrc.4416] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2015] [Revised: 12/29/2015] [Accepted: 01/07/2016] [Indexed: 06/05/2023]
Abstract
The remarkable flexibility of human red blood cells (RBCs) allows them to assume a range of shapes in normal and disease states. Biochemical mechanisms and energetic requirements associated with changes in RBC geometry are not well understood because of a lack of experimental procedures to fix and study cells in different morphological forms. By incorporating RBCs into stretchable gelatin hydrogels, we created conditions for adjustable elongation of their normal discocytic shape in all orientations. As the RBC-containing gels were stretched or compressed, the changes in the cell morphology were studied by using 1 H-PGSE-NMR spectroscopy. Measurements of the apparent diffusion coefficient of water along the three orthogonal directions revealed tuneable anisotropy in the environment of the hydrogel samples. Light microscopy was also used for recording the extent to which RBCs were distorted in a stretched gel that had been set around them. Having demonstrated the applicability of NMR diffusometry to detect morphological changes of immobilised cells, we have laid the groundwork for future investigations of controllably distorted RBCs. Specifically, we expect studies of metabolic and biophysical properties of the physically deformed cells, thus inferring the connection between intracellular physico-chemical processes and RBC morphology. Copyright © 2016 John Wiley & Sons, Ltd.
Collapse
Affiliation(s)
- Dmitry Shishmarev
- School of Molecular Bioscience, University of Sydney, Sydney, NSW, 2006,, Australia
| | - Konstantin I Momot
- School of Chemistry, Physics and Mechanical Engineering, Queensland University of Technology, Brisbane, QLD, 4001,, Australia
| | - Philip W Kuchel
- School of Molecular Bioscience, University of Sydney, Sydney, NSW, 2006,, Australia
| |
Collapse
|
10
|
Shishmarev D, Kuchel PW. NMR magnetization-transfer analysis of rapid membrane transport in human erythrocytes. Biophys Rev 2016; 8:369-384. [PMID: 28510013 PMCID: PMC5425803 DOI: 10.1007/s12551-016-0221-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2016] [Accepted: 09/13/2016] [Indexed: 10/20/2022] Open
Abstract
Nuclear magnetic resonance (NMR) magnetization-transfer (MT) experiments provide a convenient tool for studying rapid sub-second membrane-transport processes in situ in metabolically active cells. These experiments are used with membrane-permeable substances when separate (resolved) NMR signals are observed from their populations inside and outside the cells. Here, we provide a description of the theory and practice of the most common NMR MT experiments that have been used to study membrane-transport processes in human erythrocytes (red blood cells; RBCs). The procedures, involved in the analysis of the experimental data for defining mechanisms of transport, and for estimating values of kinetic parameters in the corresponding mathematical models, are given special attention.
Collapse
Affiliation(s)
- Dmitry Shishmarev
- School of Life and Environmental Sciences, The University of Sydney, Sydney, NSW, 2006, Australia
| | - Philip W Kuchel
- School of Life and Environmental Sciences, The University of Sydney, Sydney, NSW, 2006, Australia.
| |
Collapse
|