Modeling and Characterization of a Chemomechanical Actuator Based on Protein Transporters

2007 ◽  
Author(s):  
Vishnu Baba Sundaresan ◽  
Donald J. Leo
Keyword(s):  
Cell Membrane ◽  
Cell Membranes ◽  
Fluid Transport ◽  
Sucrose Concentration ◽  
Yeast Cells ◽  
Facilitated Diffusion ◽  
Flux Rate ◽  
Artificial Membrane ◽  
Saturation Concentration ◽  
Protein Transporters

Plants and animal cells are naturally occurring actuators that exhibit force and motion driven by fluid transport through the cell membrane. The protein transporters embedded in the cell membrane serve as the selective gateway for ion and fluid transport. The actuator presented in this work generates force and deformation from mass transport through an artificial membrane with protein transporters extracted from plant cell membranes. The artificial membrane is formed from purified 1-Palmitoyl-2-Oleoyl-sn-Glycero-3-[Phospho-L-Serine] (Sodium Salt) (POPS), 1-Palmitoyl-2-Oleoyl-sn-Glycero-3-Phosphoethanolamine (POPE) lipids and supported on a porous substrate. The protein transporter used in the actuator membrane is a proton-sucrose cotransporter, SUT4, extracted from yeast cells that genetically modified to grow the cotransporter in their cell membranes. The SUT4 transporter conducts proton and sucrose from the side of the membrane with higher concentration and carries water molecules across the membrane. It is observed from transport characterization experiments that fluid flux through the membrane varies with the applied sucrose concentration and hence is chosen as the control stimulus in the actuator. A modified four-state facilitated diffusion model is applied to the transport characterization data to compute the two characteristic parameters for fluid transport, saturation concentration and translocation rate, through the membrane. The flux rate through the membrane is observed to increase with the concentration till a particular value and saturates at a higher concentration. The concentration at which the flux rate through the membrane saturates is referred to as the saturation concentration. The saturation concentration for the actuator is experimentally found to be 6±0.6mM sucrose on the side with lower pH. The corresponding maximum translocation rate is found to be 9.6±1.2 nl/μ.cm2.min. The maximum steady state deformation produced by the actuator is observed at 30 mM sucrose that corresponds to a force of 0.89 mN.

Chemo-electrical energy conversion of Adenosine triphosphate in a Biological Ion Transporter

2006 ◽  
Vol 949 ◽  
Author(s):  
Vishnu Baba Sundaresan ◽  
Stephen Andrew Sarles ◽  
Brian J Goode ◽  
Donald J Leo
Keyword(s):  
Cell Membranes ◽  
Fluid Transport ◽  
Lipid Membrane ◽  
Higher Plants ◽  
High Capacity ◽  
Power Source ◽  
Yeast Cells ◽  
Constant Current ◽  
Sucrose Transport ◽  
Long Distance

ABSTRACTIon transport across cell membranes happens through protein channels and pumps expending concentration gradients, electrical gradients and energy from chemical reactions. Ion exchange in cell membranes is responsible for nutrient transport from production sites to where they are broken down to release energy. Sucrose transport is vital for growth in higher plants and recent research has led to the discovery of a class of sugar carriers called SUT4. The SUT4 transporter is a low affinity, high capacity proton-sucrose transporter that participates in long distance sucrose transport in higher plants. We demonstrated the possibility to use purified SUT4 transporter proteins — with the genetic code from Arabidopsis thaliana expressed on yeast cells — for fluid transport driven by pH gradient and from exergonic ATP hydrolysis reaction in the presence of ATP-ase enzyme. The SUT4 proteins were reconstituted on a planar bilayer lipid membrane formed from 1-Palmitoyl-2-Oleoyl-sn-Glycero-3-[Phospho-L-Serine] (Sodium Salt) (POPS), 1-Palmitoyl-2-Oleoyl-sn-Glycero- 3-Phosphoethanolamine (POPE) phospholipids on a porous substrate. This article builds upon our previous work to harness energy from the ATP-ase reaction using SUT4 to produce a proton current through SUT4 and demonstrates the technical feasibility to generate electrical current in an external circuit. The results from our characterization experiments on a single cell demonstrate that the power source behaves like a constant current power source with an internal resistance of 10-22 kΩ and produces a peak power of 150 nW.

scholarly journals S. cerevisiae Outer and Inner Membranes are Compromised upon Benzyl Alcohol Treatment

2021 ◽  
Vol 8 (2) ◽  
pp. 35-39
Author(s):  
Ergüden Bengü
Keyword(s):  
Cell Wall ◽  
Cell Membrane ◽  
Yeast Cell ◽  
Benzyl Alcohol ◽  
Cell Membranes ◽  
Antifungal Agents ◽  
Fungal Infections ◽  
New Drugs ◽  
Yeast Cells ◽  
Fungal Cell

Although there are innovations in the treatment of diseases caused by fungi and medicines with multiple targets have been developed, the search for a drug with a broad spectrum and without any side effects continues to date. It is generally accepted that determining the cellular target responsible for the toxic effect opens up new possibilities for the development of new drugs. Especially the effects of antifungal agents on the surface components of the fungal cell, on cell wall synthesis and the identification of the target site are crucial in antifungal drug development. Thus studies on the fungal cell membranes in connection with the antifungal agents, aim to develop new strategies for the therapy of fungal infections. Antifungal agents targeting fungal cell wall and cell membrane components have increased in importance in clinical studies. In this study, understanding the mechanism of action of benzyl alcohol, a known membrane fluidizer, and the determination of its cellular targets are aimed. We have shown that in the presence of sorbitol, the osmotic stabilizer, benzyl alcohol becomes less effective against yeast cell. Moreover, benzyl alcohol disrupts cell membrane, causing leakage of ions to the extracellular medium. Nuclear membrane is distorted upon treatment of yeast cells with benzyl alcohol. Thus, we conclude that both outer and inner yeast cell membranes are compromised by the action of benzyl alcohol.

scholarly journals A DISTINCTIVE CELL CONTACT IN THE RAT ADRENAL CORTEX

1972 ◽  
Vol 53 (1) ◽  
pp. 148-163 ◽  
Author(s):  
Daniel S. Friend ◽  
Norton B. Gilula
Keyword(s):  
Cell Membrane ◽  
Adrenal Cortex ◽  
Cell Membranes ◽  
Freeze Fracture ◽  
Typical Feature ◽  
Cell Contact ◽  
Cortical Cells ◽  
Cell Dispersion ◽  
Extensive Cell ◽  
Distinctive Cell

Extensive cell contacts which resemble septate junctions occur between cells in the three major zones of the rat adrenal cortex. Characteristically, they extend between small intercellular canaliculi and the periendothelial space, frequently interrupted by gap junctions and rarely by desmosomes. Zonulae occludentes have not been identified in the adrenal cortex. Along this distinctive cell contact, the cell membranes of apposing cells are separated by 210–300 a bisected by irregularly spaced 100–150-A extracellular particles which are often circular in profile. In lanthanum preparations, these particles appear to form a continuous chain throughout the intercellular space and are visualized as an alveolate structure in sections parallel to the plane of the cell membrane. The cell membrane in the area of septate-like contact does not differ from nonjunctional areas of the cell membrane in freeze-fracture replicas. The cell contact retains its integrity after cell dispersion and after the separation of cell membranes from disrupted cells. The intercellular particles also persist after brief extraction in lipid solvents. Besides adherence, possible functions of this adrenal contact include maintenance of the width of the extracellular space, the provision of channels between intercellular canaliculi and the bloodstream, and utilization as cation depots. Similar structures are also present between adrenal cortical cells of several other species and between interstitial cells of the testis. This type of cell contact may, in fact, be a typical feature of steroid-hormone-secreting tissues in vertebrates.

scholarly journals Pathogenesis of shigella diarrhea. VII. Evidence for a cell membrane toxin receptor involving β1 {arrow} 4-linked N-acetyl-D-glucosamine oligomers

1977 ◽  
Vol 146 (2) ◽  
pp. 535-546 ◽  
Author(s):  
GT Keusch ◽  
M Jacewicz
Keyword(s):  
Cell Membrane ◽  
Cholera Toxin ◽  
Liver Cell ◽  
Hela Cells ◽  
Mammalian Cells ◽  
Cell Membranes ◽  
Proteolytic Enzymes ◽  
Cell Monolayer ◽  
Toxin Receptor ◽  
Toxin Uptake

The binding of ShigeUa dysenteriae 1 cytotoxin to HeLa cells in culture and to isolated rat liver cell membranes was studied by means of an indirect consumption assay of toxicity from the medium, or by determination of cytotoxicity to the HeLa cell monolayer. Both liver cell membranes and HeLa cells removed toxicity from the medium during incubation, in contrast to WI-38 and Y-1 mouse adrenal tumor cells, both of which neither bound nor were affected by the toxin. Uptake of toxin was directly related to concentration of membranes added, time,and temperature, and indirectly related to the ionic strength of the buffer used. The chemical nature of the membrane receptor was characterized by using three principal approaches: (a) enzymatic sensitivity; (b) competitive inhibition and (c) receptor blockade studies. The receptor was destroyed by proteolytic enzymes, phospholipases (which markedly altered the gross appearance of the membrane preparation) and by lysozyme, but not by a variety of other enzymes. Of 28 carbohydrate and glycoprotein haptens studied, including cholera toxin and ganglioside, only the chitin oligosaccharide lysozyme substrates, per N-acetylated chitotriose, chitotetraose, and chitopentaose were effective competitive inhibitors. Greatest inhibition was found with the trimer, N, N', N" triacetyl chitotriose. Of three lectins studied as possible receptor blockers, including phytohemagglutinin, concanavalin A, and wheat germ agglutinin, only the latter, which is known to possess specific binding affinity for N, N', N" triacetyl chitotriose, was able to block toxin uptake. Evidence from all three approaches indicate, therefore, existence of a glycoprotein toxin receptor on mammalian cells, with involvement of oligomeric β1{arrow}4-1inked N-acetyl glucosamine in the receptor. This receptor is clearly distinct from the G(M1) ganglioside thought to be involved in the binding of cholera toxin to the cell membrane of a variety of cell types susceptible to its action.

scholarly journals Estimates of Michaelis-Menten Constants for the Two Membranes of the Brain Endothelium

1984 ◽  
Vol 4 (2) ◽  
pp. 241-249 ◽  
Author(s):  
Albert Gjedde ◽  
Ove Christensen
Keyword(s):  
Steady State ◽  
Endothelial Cell ◽  
Transport Properties ◽  
Glucose Transport ◽  
Cell Membranes ◽  
Experimental Studies ◽  
Facilitated Diffusion ◽  
Capillary Endothelial Cells ◽  
The Individual ◽  
Tracer Experiments

Tracer studies on facilitated diffusion across the blood–brain barrier lead to the calculation of Michaelis-Menten constants that describe the rate of transport. However, the barrier consists of two endothelial cell membranes, and the relevance of single Michaelis-Menten constants in relation to the two cell membranes is unknown. We have formulated a model of two endothelial cell membranes and show that the measured Michaelis-Menten constants are simple functions of the properties of the individual membranes when transport across the endothelium is rapid ( P1 > 10−6 cm s−1). We also show that the Michaelis-Menten constants determined in tracer experiments describe facilitated diffusion in the steady state only if the two membranes have similar transport properties. As an application of this observation, we have examined three experimental studies that measure glucose transport in the steady state and show that the Michaelis-Menten constants for glucose transport calculated from the tracer experiments are equal to the constants calculated from the steady-state experiments. We conclude that the luminal and abluminal membranes of brain capillary endothelial cells have equal glucose transport properties.

Ammonia movement and distribution after exercise across white muscle cell membranes in rainbow trout

1996 ◽  
Vol 271 (3) ◽  
pp. R738-R750 ◽  
Author(s):  
Y. Wang ◽  
G. J. Heigenhauser ◽  
C. M. Wood
Keyword(s):  
Membrane Potential ◽  
Cell Membrane ◽  
Intracellular Ph ◽  
Muscle Cell ◽  
Cell Membranes ◽  
White Muscle ◽  
Extracellular Ph ◽  
Posterior Portion ◽  
Arterial Inflow ◽  
Muscle Cell Membrane

Manipulations of pH and electrical gradients in a perfused preparation were used to analyze the factors controlling ammonia distribution and flux in trout white muscle after exercise. Trout were exercised to exhaustion, and then an isolated-perfused white muscle preparation with discrete arterial inflow and venous outflow was made from the posterior portion of the tail. The tail-trunks were perfused with low (7.4)-, medium (7.9)-, and high (8.4)-pH saline, achieved by varying HCO3- concentration ([HCO3-]) at constant Pco2. Intracellular and extracellular pH, ammonia, CO2, K+, Na+, and Cl- were measured. Muscle intracellular pH was not affected by changes in extracellular pH. Increasing extracellular pH caused a decrease in the transmembrane NH3 partial pressure (PNH3) gradient and a decrease in ammonia efflux. When extracellular K+ concentration was increased from 3.5 to 15 mM in the medium-pH group, a depolarization of the muscle cell membrane potential from -92 to -60 mV and a 0.1-unit depression in intracellular pH occurred. Ammonia efflux increased despite a marked reduction in the PNH3 gradient. Amiloride (10(-4) M) had no effect, indicating that Na+/H(+)-NH4+ exchange does not participate in ammonia transport in this system. A comparison of observed intracellular-to-extracellular ammonia distribution ratios with those modeled according to either pH or Nernst potential distributions supports a model in which ammonia distribution across white muscle cell membranes is affected by both pH and electrical gradients, indicating that the membranes are permeable to both NH3 and NH4+. Membrane potential, acting to retain high levels of NH4+ in the intracellular compartment, appears to have the dominant influence during the postexercise period. However, at rest, the pH gradient may be more important, resulting in much lower intracellular ammonia levels and distribution ratios. We speculate that the muscle cell membrane NH3-to-NH4+ permeability ratio in trout may change between the rest and postexercise condition.

A Convenient Method for Preparing the Cell-Membrane Network of the Wool Fiber, and a Note on the Effect of Ethanol on the Membranes in the Intact Fiber

1976 ◽  
Vol 46 (5) ◽  
pp. 360-366 ◽  
Author(s):  
K. Rachel Makinson
Keyword(s):  
Cell Membrane ◽  
Ambient Temperature ◽  
Convenient Method ◽  
Cell Membranes ◽  
Cortical Cell ◽  
Wool Fiber ◽  
Rapid Preparation ◽  
Cuticular Membrane ◽  
Expanded Form

A method is described for the rapid preparation of the cell-membrane network of a wool fiber in an expanded form suitable for microscopy. The form of the network is considerably modified by prior soaking of the fiber in ethanol at ambient temperature; this is ascribed to extraction of lipids from the membranes, so destroying their mutual adhesion by releasing them from the intercellular cement. A modification of the preparative technique is described that produces cortical cell membranes inside a tube of mutually adhering, relatively unaltered cuticle cells. This modification reveals particularly clearly the bilaterality of the cortex and any differences in reactions of the cuticle around the circumference of the fiber. Some earlier work on the existence of a “sub-cutis,” “sub-cuticular membrane,” or “zwischenmembran” is discussed and reinterpreted in the light of certain features observed in the course of this work. Deposition of polymers on the fiber makes the cuticle less extensible, so that it may split during preparation of the membranes.

Electron Microscopic Study of Penetration of Newcastle Disease Virus into Cells Leading to Formation of Polykaryocytes

1967 ◽  
Vol 2 (1) ◽  
pp. 71-76
Author(s):  
N. MEISELMAN ◽  
A. KOHN ◽  
D. DANON
Keyword(s):  
Epithelial Cells ◽  
Cell Membrane ◽  
Newcastle Disease Virus ◽  
Microscopic Study ◽  
Disease Virus ◽  
Newcastle Disease ◽  
Cell Membranes ◽  
Viral Envelope ◽  
Electron Microscopic ◽  
Input Multiplicity

Treatment of FL or Lu 106 epithelial cells with Newcastle disease virus (NDV) at an input multiplicity of 500 EID50 per cell induces in these cells the formation of polykaryocytes at the end of 2-3 h of contact. Electron micrographs of such NDV-treated monolayers after 2-10 min of incubation show the presence of virions adsorbed to the cell membranes, in vacuoles and with the viral envelope partly fused with the cell membrane. In polykaryocytes induced by NDV, remnants of cell membranes showing numerous breaks may still be present after 3 h.

Steps in p-aminohippurate transport by kidney slices

1958 ◽  
Vol 196 (1) ◽  
pp. 86-92 ◽  
Author(s):  
Ernest C. Foulkes ◽  
Benjamin F. Miller
Keyword(s):  
Cell Membrane ◽  
Transport System ◽  
Rate Constants ◽  
Extracellular Space ◽  
Concentration Ratio ◽  
Tissue Concentration ◽  
The Other ◽  
Facilitated Diffusion ◽  
Tubular Lumen ◽  
Cortical Slices

The existence of two intracellular fractions of PAH was demonstrated in renal cortical slices of the rabbit on incubation with C14-labeled PAH. One of these fractions is rapidly diffusible and rapidly equilibrates with extracellular PAH. The other fraction, in contrast, diffuses and equilibrates slowly; it is responsible for the high slice to medium concentration ratio of PAH. On the basis of these results a model of the PAH transport system in slices is proposed. This consists of step I, the diffusion of PAH from the medium into the extracellular space in the tissue; there follows step II, a facilitated diffusion step at the peritubular cell membrane; within the cell step III builds up a high tissue concentration of PAH; finally step IV transfers PAH across the luminal border of the cell into the tubular lumen from which it may diffuse back into the medium. Experiments were designed in which each of these steps could be measured individually and their rate constants determined. Alteration of the value of these rate constants by specific drugs localizes the action of such compounds at the peritubular cell membrane (Benemid, 9-alphafluorohydrocortisone) or at the level of both steps II and III in the case of DNP, octanoate and Diodrast. An explanation is also offered for the effect of cold on PAH influx and efflux. It can be calculated that the contribution of step IV to the turnover of PAH in slices is not quantitatively significant.

scholarly journals Designer artificial membrane binding proteins to direct stem cells to the myocardium

2019 ◽  
Vol 10 (32) ◽  
pp. 7610-7618 ◽  
Author(s):  
Wenjin Xiao ◽  
Thomas I. P. Green ◽  
Xiaowen Liang ◽  
Rosalia Cuahtecontzi Delint ◽  
Guillaume Perry ◽  
...  
Keyword(s):  
Stem Cells ◽  
Cell Membrane ◽  
Binding Proteins ◽  
Membrane Binding ◽  
Heart Tissue ◽  
Streptococcus Gordonii ◽  
Human Stem Cells ◽  
Artificial Membrane ◽  
Membrane Modification

We present a new cell membrane modification methodology where the inherent heart tissue homing properties of the infectious bacteriaStreptococcus gordoniiare transferred to human stem cells.

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