Biomaterial Database

Electrochemical proton gradient in inverted membrane vesicles from Escherichia coli. 1980

W W Reenstra, and L Patel, and H Rottenberg, and H R Kaback

Inverted membrane vesicles prepared from Escherichia coli ML 308-225 generate a transmembrane electrochemical proton gradient (delta mu H+; interior positive and acid) during oxidation of D-lactate, succinate, reduced phenazine methosulfate, or NADH or hydrolysis of ATP. Using the distribution of the lipophilic anion thiocyanate to measure the membrane potential (delta psi) and the permeant weak base methylamine to measure the pH gradient (delta pH), maximal values for delta psi H+ of approximately +160 mV are obtained. Many of the properties of delta psi H+ in inverted vesicles are similar to those described previously in right-side-out vesicles [Ramos, S., & Kaback, H.R. (1977) Biochemistry 16, 848]: (1) the magnitude of the delta psi (interior positive) generated in the presence of D-lactate or reduced phenazine methosulfate is similar to that observed in right-side-out vesicles but of opposite polarity and independent of pH from 5.5 to 8.0; (2) plots of delta pH vs. internal pH in the right-side-out vesicles are similar with D-lactate as the electron donor; (3) as observed with right-side-out vesicles, dissipation of delta psi or delta pH leads to a concomitant increase in the other parameter without a change in the rate of respiration; (4) inverted vesicles catalyze Na+ accumulation, and it is apparent that the process can be driven by either delta psi (interior positive) or delta pH (interior acid).

UI	MeSH Term	Description	Entries
D007700	Kinetics	The rate dynamics in chemical or physical systems.
D008564	Membrane Potentials	The voltage differences across a membrane. For cellular membranes they are computed by subtracting the voltage measured outside the membrane from the voltage measured inside the membrane. They result from differences of inside versus outside concentration of potassium, sodium, chloride, and other ions across cells' or ORGANELLES membranes. For excitable cells, the resting membrane potentials range between -30 and -100 millivolts. Physical, chemical, or electrical stimuli can make a membrane potential more negative (hyperpolarization), or less negative (depolarization).	Resting Potentials,Transmembrane Potentials,Delta Psi,Resting Membrane Potential,Transmembrane Electrical Potential Difference,Transmembrane Potential Difference,Difference, Transmembrane Potential,Differences, Transmembrane Potential,Membrane Potential,Membrane Potential, Resting,Membrane Potentials, Resting,Potential Difference, Transmembrane,Potential Differences, Transmembrane,Potential, Membrane,Potential, Resting,Potential, Transmembrane,Potentials, Membrane,Potentials, Resting,Potentials, Transmembrane,Resting Membrane Potentials,Resting Potential,Transmembrane Potential,Transmembrane Potential Differences
D002462	Cell Membrane	The lipid- and protein-containing, selectively permeable membrane that surrounds the cytoplasm in prokaryotic and eukaryotic cells.	Plasma Membrane,Cytoplasmic Membrane,Cell Membranes,Cytoplasmic Membranes,Membrane, Cell,Membrane, Cytoplasmic,Membrane, Plasma,Membranes, Cell,Membranes, Cytoplasmic,Membranes, Plasma,Plasma Membranes
D004926	Escherichia coli	A species of gram-negative, facultatively anaerobic, rod-shaped bacteria (GRAM-NEGATIVE FACULTATIVELY ANAEROBIC RODS) commonly found in the lower part of the intestine of warm-blooded animals. It is usually nonpathogenic, but some strains are known to produce DIARRHEA and pyogenic infections. Pathogenic strains (virotypes) are classified by their specific pathogenic mechanisms such as toxins (ENTEROTOXIGENIC ESCHERICHIA COLI), etc.	Alkalescens-Dispar Group,Bacillus coli,Bacterium coli,Bacterium coli commune,Diffusely Adherent Escherichia coli,E coli,EAggEC,Enteroaggregative Escherichia coli,Enterococcus coli,Diffusely Adherent E. coli,Enteroaggregative E. coli,Enteroinvasive E. coli,Enteroinvasive Escherichia coli
D006863	Hydrogen-Ion Concentration	The normality of a solution with respect to HYDROGEN ions; H+. It is related to acidity measurements in most cases by pH	pH,Concentration, Hydrogen-Ion,Concentrations, Hydrogen-Ion,Hydrogen Ion Concentration,Hydrogen-Ion Concentrations
D001692	Biological Transport	The movement of materials (including biochemical substances and drugs) through a biological system at the cellular level. The transport can be across cell membranes and epithelial layers. It also can occur within intracellular compartments and extracellular compartments.	Transport, Biological,Biologic Transport,Transport, Biologic
D012964	Sodium	A member of the alkali group of metals. It has the atomic symbol Na, atomic number 11, and atomic weight 23.	Sodium Ion Level,Sodium-23,Ion Level, Sodium,Level, Sodium Ion,Sodium 23