Direct Monitoring of Bicarbonate Transport by Emission Spectroscopy

The transmembrane transport of bicarbonate is a key step in many important biological processes, while problems with bicarbonate transport are at the origin of various diseases. Over the past 10 years, many anionophores that have been developed for the transport of chloride, have also been tested as bicarbonate transporters. However, methodology to directly monitor the kinetics of transport of bicarbonate is lacking, hence indirect methods have been used, which mainly rely on the monitoring of chloride concentrations.Here we present an assay that allows the kinetics of bicarbonate transport into liposomes to be monitored directly, using emission spectroscopy. The assay utilises an encapsulated europium(III) complex, which exhibits a large increase in emission upon binding of bicarbonate. The advantages of this assay over existing methodology are that concentrations of bicarbonate are monitored directly and with a high sensitivity. This allows studies at very low concentrations of anionophores, and for the mechanisms of bicarbonate transport to be unravelled. We have distinguished classical antiport with bicarbonate from mechanisms involving CO2 diffusion and the dissipation of a pH gradient. Furthermore, the use of a standard fluorescence spectrometer and liposomes with a diameter ~200 nm makes this assay readily and reliably applicable in many laboratories, where it can facilitate the development of bicarbonate transporters for applications in physiological studies or therapies.

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Direct Monitoring of Bicarbonate Transport by Emission Spectroscopy

10.26434/chemrxiv.12624425.v3 ◽

2021 ◽

Author(s):

Luis Martínez-Crespo ◽

Sarah Hewitt ◽

Nicola Alessandro De Simone ◽

Vladimir Sindelar ◽

Anthony P. Davis ◽

...

Keyword(s):

Emission Spectroscopy ◽

High Sensitivity ◽

Bicarbonate Transport ◽

Biological Processes ◽

Indirect Methods ◽

The Past ◽

Low Concentrations ◽

Bicarbonate Transporters ◽

Fluorescence Spectrometer ◽

Kinetics Of

The transmembrane transport of bicarbonate is a key step in many important biological processes, while problems with bicarbonate transport are at the origin of various diseases. Over the past 10 years, many anionophores that have been developed for the transport of chloride, have also been tested as bicarbonate transporters. However, methodology to directly monitor the kinetics of transport of bicarbonate is lacking, hence indirect methods have been used, which mainly rely on the monitoring of chloride concentrations.Here we present an assay that allows the kinetics of bicarbonate transport into liposomes to be monitored directly, using emission spectroscopy. The assay utilises an encapsulated europium(III) complex, which exhibits a large increase in emission upon binding of bicarbonate. The advantages of this assay over existing methodology are that concentrations of bicarbonate are monitored directly and with a high sensitivity. This allows studies at very low concentrations of anionophores, and for the mechanisms of bicarbonate transport to be unravelled. We have distinguished classical antiport with bicarbonate from mechanisms involving CO2 diffusion and the dissipation of a pH gradient. Furthermore, the use of a standard fluorescence spectrometer and liposomes with a diameter ~200 nm makes this assay readily and reliably applicable in many laboratories, where it can facilitate the development of bicarbonate transporters for applications in physiological studies or therapies.

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Direct Monitoring of Bicarbonate Transport by Emission Spectroscopy

10.26434/chemrxiv.12624425 ◽

2020 ◽

Author(s):

Luis Martínez-Crespo ◽

Sarah Hewitt ◽

Nicola Alessandro De Simone ◽

Vladimir Sindelar ◽

Anthony P. Davis ◽

...

Keyword(s):

Emission Spectroscopy ◽

High Sensitivity ◽

Bicarbonate Transport ◽

Biological Processes ◽

Indirect Methods ◽

The Past ◽

Low Concentrations ◽

Bicarbonate Transporters ◽

Fluorescence Spectrometer ◽

Kinetics Of

The transmembrane transport of bicarbonate is a key step in many important biological processes, while problems with bicarbonate transport are at the origin of various diseases. Over the past 10 years, many anionophores that have been developed for the transport of chloride, have also been tested as bicarbonate transporters. However, methodology to directly monitor the kinetics of transport of bicarbonate is lacking, hence indirect methods have been used, which mainly rely on the monitoring of chloride concentrations.Here we present an assay that allows the kinetics of bicarbonate transport into liposomes to be monitored directly, using emission spectroscopy. The assay utilises an encapsulated europium(III) complex, which exhibits a large increase in emission upon binding of bicarbonate. The advantages of this assay over existing methodology are that concentrations of bicarbonate are monitored directly and with a high sensitivity. This allows studies at very low concentrations of anionophores, and for the mechanisms of bicarbonate transport to be unravelled. We have distinguished classical antiport with bicarbonate from mechanisms involving CO2 diffusion and the dissipation of a pH gradient. Furthermore, the use of a standard fluorescence spectrometer and liposomes with a diameter ~200 nm makes this assay readily and reliably applicable in many laboratories, where it can facilitate the development of bicarbonate transporters for applications in physiological studies or therapies.

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Kinetics of bicarbonate transport in human red blood cell membranes at body temperature.

The Journal of General Physiology ◽

10.1085/jgp.108.6.565 ◽

1996 ◽

Vol 108 (6) ◽

pp. 565-575 ◽

Cited By ~ 12

Author(s):

P K Gasbjerg ◽

P A Knauf ◽

J Brahm

Keyword(s):

Body Temperature ◽

Continuous Flow ◽

Anion Transport ◽

Bicarbonate Transport ◽

Red Cell ◽

Flow Tube ◽

Low Concentrations ◽

Ping Pong ◽

Red Blood Cell Membranes ◽

Kinetics Of

We studied unidirectional [14C]HCO3- efflux from human resealed red cell ghosts with 1 mM acetazolamide under self-exchange conditions at pH = pH(i = o) 7.4-9.0 and 0-38 degrees C by means of the Millipore-Swinnex and continuous flow tube filtering techniques. 14CO2 loss from cells to efflux medium and further to the atmosphere was insignificant. [14C]HCO3- efflux was determined at pH 7.8, 38 degrees C under symmetric variation of the HCO3- concentrations (C(i = o)), and asymmetric conditions: C(i) varied, C(o) constant, or C(o) varied, C(i) constant. MM-fit, Jeff = Jmaxeff x C x (C + K1/2)-1, used to describe the concentration dependence of Jeff,o when only C(o) varied, yields at C(i) = 50 mM: K1/2o = 3.8 mMJ, Jmaxeff.o = 20 nmol cm-2 s-1; at C(i) = 165 mM: K1/2o = 10 mM, Jmaxeff.o = 32 nmol cm-2 s-1. When C(i) varied, noncompetitive self inhibition by HCO3- binding (inhibitor constant K1) to an intracellular site was included (MS-fit). Under conditions of (a) symmetry: C(i = o) = 9-600 mM, K1/2s = 173 mM, K1 = 172 mM, and Jmaxeff,s = 120 nmol cm-2 s-1, (b) asymmetry: C(o) = 50 mM, K1/2i = 116 mM, K1 = 136 mM, and Jmaxeff,i = 92 nmol cm-2 s-1. All flux parameters accord with the ping-pong model for anion exchange. The data for C(i) < 200 mM also fit well to the MM equation, but K1/2 and Jmaxeff are different from the MS-fit and are inconsistent with the ping-pong model. Thus, self-inhibition (MS-fit) must be included even at low concentrations. As at 0 degree C, the system is asymmetric: 8-10 times more unloaded transport sites face inward than outward when C(i = o). Jeff,s was not mono-exponentially dependent on temperature at 0-38 degrees C, indicating that the transmembrane anion transport is controlled by several rate constants with different temperature dependencies. Jeff,s was not significantly affected by increasing pH(i = o) from 7.4 to 7.8, but it decreased by 50% when pH was raised to 9.0.

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Fluorescent potentiometric dyes for membrane-potential imaging

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100168566 ◽

1994 ◽

Vol 52 ◽

pp. 166-167

Author(s):

Leslie M. Loew

Keyword(s):

Membrane Potential ◽

Single Cells ◽

Quantitative Imaging ◽

Optical Recording ◽

Biological Processes ◽

Major Focus ◽

The Past ◽

Excitable Systems ◽

Major Application ◽

The Impact

A major application of potentiometric dyes has been the multisite optical recording of electrical activity in excitable systems. After being championed by L.B. Cohen and his colleagues for the past 20 years, the impact of this technology is rapidly being felt and is spreading to an increasing number of neuroscience laboratories. A second class of experiments involves using dyes to image membrane potential distributions in single cells by digital imaging microscopy - a major focus of this lab. These studies usually do not require the temporal resolution of multisite optical recording, being primarily focussed on slow cell biological processes, and therefore can achieve much higher spatial resolution. We have developed 2 methods for quantitative imaging of membrane potential. One method uses dual wavelength imaging of membrane-staining dyes and the other uses quantitative 3D imaging of a fluorescent lipophilic cation; the dyes used in each case were synthesized for this purpose in this laboratory.

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Kinetics of Various 99mTc-Sn-Pyrophosphate Compounds in the Rat

Nuklearmedizin ◽

10.1055/s-0037-1620623 ◽

1977 ◽

Vol 16 (04) ◽

pp. 157-162 ◽

Cited By ~ 1

Author(s):

C. Schümichen ◽

B. Mackenbrock ◽

G. Hoffmann

Keyword(s):

Normal Saline ◽

Half Life ◽

Compound A ◽

Short Half Life ◽

Low Concentrations ◽

The Stability ◽

Kinetics Of ◽

In Vitro Stability

SummaryThe bone-seeking 99mTc-Sn-pyrophosphate compound (compound A) was diluted both in vitro and in vivo and proved to be unstable both in vitro and in vivo. However, stability was much better in vivo than in vitro and thus the in vitro stability of compound A after dilution in various mediums could be followed up by a consecutive evaluation of the in vivo distribution in the rat. After dilution in neutral normal saline compound A is metastable and after a short half-life it is transformed into the other 99mTc-Sn-pyrophosphate compound A is metastable and after a short half-life in bone but in the kidneys. After dilution in normal saline of low pH and in buffering solutions the stability of compound A is increased. In human plasma compound A is relatively stable but not in plasma water. When compound B is formed in a buffering solution, uptake in the kidneys and excretion in urine is lowered and blood concentration increased.It is assumed that the association of protons to compound A will increase its stability at low concentrations while that to compound B will lead to a strong protein bond in plasma. It is concluded that compound A will not be stable in vivo because of a lack of stability in the extravascular space, and that the protein bond in plasma will be a measure of its in vivo stability.

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Submerged upflow biotower operation and computer simulation

Water Science & Technology ◽

10.2166/wst.1994.0554 ◽

1994 ◽

Vol 30 (11) ◽

pp. 143-146

Author(s):

Ronald D. Neufeld ◽

Christopher A. Badali ◽

Dennis Powers ◽

Christopher Carson

Keyword(s):

Computer Simulation ◽

Benzoic Acid ◽

Computer Model ◽

Rate Constants ◽

Batch Mode ◽

Operational Conditions ◽

First Order ◽

Low Concentrations ◽

Biological Transformation ◽

Kinetics Of

A two step operation is proposed for the biodegradation of low concentrations (< 10 mg/L) of BETX substances in an up flow submerged biotower configuration. Step 1 involves growth of a lush biofilm using benzoic acid in a batch mode. Step 2 involves a longer term biological transformation of BETX. Kinetics of biotransformations are modeled using first order assumptions, with rate constants being a function of benzoic acid dosages used in Step 1. A calibrated computer model is developed and presented to predict the degree of transformation and biomass level throughout the tower under a variety of inlet and design operational conditions.

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Comparison and Analysis of Computational Methods for Identifying N6 - methyladenosine Sites in Saccharomyces Cerevisiae

Current Pharmaceutical Design ◽

10.2174/1381612826666201109110703 ◽

2020 ◽

Vol 26 ◽

Author(s):

Pengmian Feng ◽

Lijing Feng ◽

Chaohui Tang

Keyword(s):

Saccharomyces Cerevisiae ◽

Computational Methods ◽

Computational Analysis ◽

Computational Prediction ◽

Experimental Methods ◽

Biological Processes ◽

Biological Functions ◽

Precise Location ◽

Future Directions ◽

The Past

Background and Purpose: N 6 -methyladenosine (m6A) plays critical roles in a broad set of biological processes. Knowledge about the precise location of m6A site in the transcriptome is vital for deciphering its biological functions. Although experimental techniques have made substantial contributions to identify m6A, they are still labor intensive and time consuming. As good complements to experimental methods, in the past few years, a series of computational approaches have been proposed to identify m6A sites. Methods: In order to facilitate researchers to select appropriate methods for identifying m6A sites, it is necessary to give a comprehensive review and comparison on existing methods. Results: Since researches on m6A in Saccharomyces cerevisiae are relatively clear, in this review, we summarized recent progresses on computational prediction of m6A sites in S. cerevisiae and assessed the performance of existing computational methods. Finally, future directions of computationally identifying m6A sites were presented. Conclusion: Taken together, we anticipate that this review will provide important guides for computational analysis of m 6A modifications.

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Study of nickel-molybdenum catalysts for methanation of carbon monoxide

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19800783 ◽

1980 ◽

Vol 45 (3) ◽

pp. 783-790 ◽

Cited By ~ 1

Author(s):

Petr Taras ◽

Milan Pospíšil

Keyword(s):

Carbon Monoxide ◽

Catalytic Activity ◽

Mixed Oxides ◽

Minor Component ◽

Fast Neutrons ◽

Scanning Calorimetry ◽

Low Concentrations ◽

Γ Rays ◽

Molybdenum Catalysts ◽

Kinetics Of

Catalytic activity of nickel-molybdenum catalysts for methanation of carbon monoxide and hydrogen was studied by means of differential scanning calorimetry. The activity of NiMoOx systems exceeds that of carrier-free nickel if x < 2, and is conditioned by the oxidation degree of molybdenum, changing in dependence on the composition in the region Mo-MoO2. The activity of the catalysts is adversely affected by irradiation by fast neutrons, dose 28.1 Gy, or by γ rays using doses in the region 0.8-52 kGy. The system is most susceptible to irradiation in the region of low concentrations of the minor component (about 1 mol.%). The dependence of changes in catalytic activity of γ-irradiated samples on the dose exhibits a maximum in the range of 2-5 kGy. The changes in catalytic activity are stimulated by the change of reactivity of the starting mixed oxides, leading to different kinetics of their reduction and modification of their adsorption properties. The irradiation of the catalysts results in lowered concentration of the active centres for the methanation reaction.

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Thermal Decomposition of Li(NTO)·2H2O and Na(NTO)·H2O (NTO = Anion of 3-Nitro-1,2,4-triazol-5-one): Kinetics Derived from T-jump/FTIR Spectroscopy

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc20060129 ◽

2006 ◽

Vol 71 (1) ◽

pp. 129-137 ◽

Cited By ~ 1

Author(s):

Yuanhua Sun ◽

Tonglai Zhang ◽

Jianguo Zhang ◽

Xiaojing Qiao ◽

Li Yang ◽

...

Keyword(s):

Ftir Spectroscopy ◽

Energetic Material ◽

Burning Surface ◽

High Sensitivity ◽

Control Voltage ◽

Differential Scanning Colorimetry ◽

Voltage Trace ◽

Dsc Method ◽

Phase Chemistry ◽

Kinetics Of

A "snapshot" simulation of the surface reaction zone is captured by a thin film of material heated rapidly to temperatures characteristic of the burning surface by using the T-jump/FTIR spectroscopy. The time-to-exotherm (tx) kinetics method derived from the control voltage trace of the Pt filament can be introduced to resolve the kinetics of an energetic material owing to its high sensitivity to the thermochemical reactions. The kinetic parameters of the two title compounds are determined under different pressures. The results show that Li(NTO)·2H2O and Na(NTO)·H2O (NTO = anion of 3-nitro-1,2,4-triazol-5-one) exhibit weak pressure dependence, their decomposition is dominated by the condensed phase chemistry irrespective of the pressure in the 0.1-1.1 MPa range. The values of Ea determined here are smaller than those given by a traditional non-isothermal differential scanning colorimetry (DSC) method, which might be resembled as the surface of explosion more closely and enabled the pyrolysis surface to be incorporated into models of steady and possibly unsteady combustion. The kinetics can also be successfully used to understand the behavior of the energetic material in practical combustion problems.

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