Liposome-based measurement of light-driven chloride transport kinetics of halorhodopsin

2021 ◽  
Vol 1863 (8) ◽  
pp. 183637
Author(s):  
Hasin Feroz ◽  
Bryan Ferlez ◽  
Hyeonji Oh ◽  
Hossein Mohammadiarani ◽  
Tingwei Ren ◽  
...  
Keyword(s):  
Chloride Transport ◽  
Transport Kinetics ◽  
Kinetics Of

Kinetics of chloride transport across fish red blood cell membranes

1995 ◽  
Vol 198 (10) ◽  
pp. 2237-2244 ◽  
Author(s):  
F Jensen ◽  
J Brahm
Keyword(s):  
Blood Cell ◽  
Red Blood Cell ◽  
Atlantic Cod ◽  
Chloride Transport ◽  
Band 3 ◽  
Transport Kinetics ◽  
Human Values ◽  
Cl Transport ◽  
Kinetics Of

The continuous flow tube method was used to investigate the kinetics of chloride transport, and its potential oxygenation-dependency, in red blood cells (RBCs) from four teleost fish species and man. A significant interspecific variation in Cl- transport kinetics was found. At 15 °C, the rate constant k for unidirectional 36Cl- efflux was significantly lower in RBCs from eel and carp than in RBCs from rainbow trout and Atlantic cod. The values of k of cod RBCs at 15 °C and of human RBCs at 37 °C were not significantly different. The volume and surface area of the RBCs were evaluated and used to calculate the apparent membrane permeability to Cl- (PCl). The magnitude of PCl followed the sequence: eel<carp<trout¾cod. PCl values in trout and cod at 15 °C were similar to human values at 37 °C. An extrapolation of human values to 15 °C revealed that the Cl- shift at this temperature was considerable faster in all four teleosts than in man. This illustrates appropriate adaption of band-3-mediated anion transport to the different temperature regimes encountered by fish and mammals. The Cl- transport kinetics did not differ significantly between oxygenated and deoxygenated RBCs in any of the species examined. The apparent absence of any effect of a change in haemoglobin oxygen-saturation may be related to the presence of a flexible link which results in minimal interaction between the membrane domain (mediating Cl- transport) and the cytoplasmic domain (to which oxygenation-dependent haemoglobin binding occurs) of band 3. In carp, Cl- transport kinetics were not influenced by pH over the extracellular pH (pHe) range 7.6­8.36, which spans the in vivo pHe range. The data are discussed in relation to the rate-limiting role of red blood cell HCO3-/Cl- exchange for CO2 excretion.

scholarly journals Light-Driven Chloride Transport Kinetics of Halorhodopsin

2018 ◽  
Vol 115 (2) ◽  
pp. 353-360 ◽  
Author(s):  
Hasin Feroz ◽  
Bryan Ferlez ◽  
Cecile Lefoulon ◽  
Tingwei Ren ◽  
Carol S. Baker ◽  
...  
Keyword(s):  
Chloride Transport ◽  
Transport Kinetics ◽  
Kinetics Of

Kinetics of the multidrug transporter (P-glycoprotein) and its reversal

1997 ◽  
Vol 77 (2) ◽  
pp. 545-590 ◽  
Author(s):  
W. D. Stein
Keyword(s):  
Final Section ◽  
Transport Kinetics ◽  
Multidrug Transporter ◽  
Chemotherapeutic Drugs ◽  
Multidrug Resistance Proteins ◽  
Binding Properties ◽  
Membrane Pump ◽  
Resistance Proteins ◽  
P Glycoprotein ◽  
Kinetics Of

Most cancer deaths result from the cancer's either being intrinsically resistant to chemotherapeutic drugs or becoming resistant after being initially sensitive. Often, in cells grown in cell culture, drug resistance correlates with the presence of one or more of the so-called P-glycoproteins or multidrug resistance proteins, products of the mdr family of genes. This review is largely concerned with the transport kinetics of the P-glycoproteins. We first present a brief overview of the P-glycoproteins, their properties, and their clinical significance. Later sections of the review expand on this material with special emphasis on the substrates of P-glycoprotein and how they cross the cell membrane, on the transport kinetics of the P-glycoprotein, on reversers of its action, and on its activity as an ATPase. In a final section, we consider the mechanism of action of P-glycoprotein as an actively transporting membrane pump. The characteristic of P-glycoprotein considered the most difficult to explain is its very broad specificity (or lack of specificity), but there are precedents for this property in well-known proteins such as serum albumin, which binds a range of molecular types, including substrates and reversers of P-glycoprotein, seemingly as broad as does P-glycoprotein. Pointing out this analogy does not provide a molecular explanation for the substrate-binding properties of P-glycoprotein but does make those properties more assimilable.

scholarly journals Unexpected Role of Electronic Coupling between Host Redox Centers in Transport Kinetics of Lithium Ions in Olivine Phosphate Materials

2021 ◽  
Author(s):  
Yu Gao ◽  
Jun Huang ◽  
Yuwen Liu ◽  
Shengli Chen
Keyword(s):  
Activation Energy ◽  
Diffusion Coefficient ◽  
Lithium Ion ◽  
Transport Kinetics ◽  
Electronic Coupling ◽  
Lithium Ions ◽  
Kinetics Of ◽  
Olivine Phosphate ◽  
Redox Centers

The discrepancy between the trend in the diffusion coefficient of lithium ion (DLi+) and that in the activation energy of ion hopping signals hidden factors determining ion transport kinetics in...

scholarly journals Carbon Nanotube Electrodes for Electrochemical Detection of Dopamine

2021 ◽  
Author(s):  
Gaurang Khot ◽  
Frank Platte ◽  
Neil Shirtcliffe ◽  
Tansu Celikel
Keyword(s):  
Electron Transport ◽  
Pyrolytic Carbon ◽  
Transport Kinetics ◽  
Electrochemical Kinetics ◽  
Current Voltage ◽  
Surface Diameter ◽  
Kinetics Of ◽  
The Brain ◽  
Anodic Region ◽  
Basal Concentration

AbstractCarbon nanotubes (CNTs) are suited for neurochemistry because of their biological inertness, ability to withstand biofouling, and superior electron transport kinetics. Dopamine, the canonical monoaminergic neuromodulator, contributes to reward, cognition and attention, however, its detection in real-time is challenging due to its low basal concentration in the brain (100nM L-1). In our present work, we fabricate pyrolytic carbon electrodes and perform a CNT coating to improve the electrochemical kinetics of dopamine. Upon CNTs coating, dopamine shows a sensitivity of 9±18nA/μM for a cylindrical electrode having a mean surface diameter of 8±4μm. Increasing the scan frequency from 10-100 Hz shows that dopamine electron transfer kinetics improves; wherein dopamine is oxidized at 0.35±0.09V and reduced to -0.10±0.05V for 10 Hz. Increasing the frequency results in a shift of oxidation peak towards the anodic region, wherein dopamine oxidizes at 0.08±3V and reduces at -0.1±0.05V for 100 Hz, thus showing that dopamine redox is reversible which can be attributed to the superior electron transport kinetics of CNTs. The sensor was able to distinguish dopamine signals against other neurochemicals like serotonin and foulant 3,4-Dihydroxyphenylacetic acid (DOPAC). The minimum chemical detection that can be performed using these nanopipettes is 50±18nM L-1, which is well below the physiological concentrations of dopamine in the brain.Graphical AbstractA: Pictorial view of background-subtracted voltammetry. The waveform used was -0.4V to 1.3 V and cycled back to -0.4V at 10 Hz. B: The voltammogram was converted as a 2-D representation, into current, voltage, and repetition to understand the dopamine oxidation. C: Background subtracted voltammetry for dopamine using 100 Hz waveform. D: The 2-D representation of current, voltage, and repetition.

Active Chloride Transport by the Gills of Rainbow Trout (Salmo Gairdneri)

1972 ◽  
Vol 56 (1) ◽  
pp. 263-272
Author(s):  
THEODORE H. KERSTETTER ◽  
LEONARD B. KIRSCHNER
Keyword(s):  
Chloride Transport ◽  
Gill Filament ◽  
Salmo Gairdneri ◽  
Apparent Effect ◽  
Chloride Uptake ◽  
Potassium Influx ◽  
The Mean ◽  
Kinetics Of ◽  
Trout Gill ◽  
Penetrating Cations

1. The kinetics of chloride transport by the irrigated trout gill have been studied. The transport system is saturable, and the half-saturation value is about 0.25mM. 2. Chloride uptake occurs equally well from solutions of non-penetrating cations and from NaCl solutions. The presence of potassium in the irrigating solution, however, significantly inhibits chloride uptake. 3. The trout gill is permeable to potassium, and there appears to be an active component to potassium influx. 4. Chloride transport is stimulated by injections of NaHCO3 and (NH4)HCO3. The carbonic anhydrase inhibitor, acetazolamide, has no apparent effect on chloride influx, and it is suggested that if a Cl-/HCO3- exchange exists in the trout gill, sufficient HCO3- can be supplied by the blood. 5. The mean intracellular potential (relative to the irrigating solution) of five gill filament cells was -32 mV. This indicates the presence of an energy barrier to chloride uptake at the outer membrane of the epithelium, and therefore it is postulated that an active step for chloride transport is located on this membrane.

Peritoneal Transport Kinetics of Glucose, Urea, and Creatinine during Infancy and Childhood

1991 ◽  
Vol 11 (4) ◽  
pp. 322-325 ◽  
Author(s):  
Cornelis H. Schröder ◽  
Marie-José Van Dreumel ◽  
Roel Reddingius ◽  
Ad G.M. Theeuwes ◽  
Hans L. Willems ◽  
...  
Keyword(s):  
Young Children ◽  
Transport Kinetics ◽  
Age Dependency ◽  
Older Children ◽  
Peritoneal Equilibration Test ◽  
Peritoneal Transport ◽  
Infancy And Childhood ◽  
Reference Curves ◽  
Kinetics Of

Peritoneal handling of glucose and metabolites is reported to be higher in young children treated with CAPD than in older children. Reference curves for the standardized peritoneal equilibration test (PET) are not available for younger ages. The present study describes the results of the PET in 19 children (mean age 5.0 years, ranging from 0.3–15) during the first month of CAPD treatment. No age dependency for the handling of glucose, urea, and creatinine could be established when the group was subdivided into 1. children below the age of 3 years, and 2. children above that age. There was, however, a significant correlation between equilibration of creatinine and age, indicating more rapid equilibration at younger ages.

Sign in / Sign up

Export Citation Format

Share Document