Biomaterial Database

A stable Na+/H+ antiporter of thermophilic bacterium PS3. 1980

K Goto, and H Hirata, and Y Kagawa

As a first step in the isolation of a stable Na+/H+ antiporter, its reaction in sonicated membrane vesicles of thermophilic bacterium PS3 has been characterized. The sonicated vesicles showed quenching of quinacrine fluorescence in either NADH oxidation or ATP hydrolysis. The quenching was reversed by the addition of Na+, Li+, Mn2+, Cd2+, and Co2+, but not of choline+ or Ca2+, regardless of their counter anions. 22Na+ was taken up into the vesicles by NADH oxidation, and the 22Na+ uptake was inhibited by the addition of an uncoupler. H+ release was observed on addition of Na+ to sonicated vesicles. The magnitude of the pH difference across the membrane induced by NADH oxidation was constant at pH 7.0 to 9.1, but the Na+/H+ antiport was affected by the pH of the medium (optimum pH-8.5). The Km's of the antiporter for Na+ and Li+ were 2.5 and 0.1 mM, respectively, but the Vmax values for the two ions were the same at pH 8.0. In the presence of Li+, no further decrease of fluorescence quenching was observed on addition of Na+ and vice versa. The Na+/H+ antiporter activity in PS3 was stable at 70 degrees C, and the optimum temperature for activity was 55-60 degrees C. In contrast to mesophilic cation/H+ antiporters, this antiporter was not inhibited by a thiol reagent.

UI	MeSH Term	Description	Entries
D010084	Oxidation-Reduction	A chemical reaction in which an electron is transferred from one molecule to another. The electron-donating molecule is the reducing agent or reductant; the electron-accepting molecule is the oxidizing agent or oxidant. Reducing and oxidizing agents function as conjugate reductant-oxidant pairs or redox pairs (Lehninger, Principles of Biochemistry, 1982, p471).	Redox,Oxidation Reduction
D002412	Cations	Positively charged atoms, radicals or groups of atoms which travel to the cathode or negative pole during electrolysis.	Cation
D006358	Hot Temperature	Presence of warmth or heat or a temperature notably higher than an accustomed norm.	Heat,Hot Temperatures,Temperature, Hot,Temperatures, Hot
D006859	Hydrogen	The first chemical element in the periodic table with atomic symbol H, and atomic number 1. Protium (atomic weight 1) is by far the most common hydrogen isotope. Hydrogen also exists as the stable isotope DEUTERIUM (atomic weight 2) and the radioactive isotope TRITIUM (atomic weight 3). Hydrogen forms into a diatomic molecule at room temperature and appears as a highly flammable colorless and odorless gas.	Protium,Hydrogen-1
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
D001419	Bacteria	One of the three domains of life (the others being Eukarya and ARCHAEA), also called Eubacteria. They are unicellular prokaryotic microorganisms which generally possess rigid cell walls, multiply by cell division, and exhibit three principal forms: round or coccal, rodlike or bacillary, and spiral or spirochetal. Bacteria can be classified by their response to OXYGEN: aerobic, anaerobic, or facultatively anaerobic; by the mode by which they obtain their energy: chemotrophy (via chemical reaction) or PHOTOTROPHY (via light reaction); for chemotrophs by their source of chemical energy: CHEMOLITHOTROPHY (from inorganic compounds) or chemoorganotrophy (from organic compounds); and by their source for CARBON; NITROGEN; etc.; HETEROTROPHY (from organic sources) or AUTOTROPHY (from CARBON DIOXIDE). They can also be classified by whether or not they stain (based on the structure of their CELL WALLS) with CRYSTAL VIOLET dye: gram-negative or gram-positive.	Eubacteria
D001693	Biological Transport, Active	The movement of materials across cell membranes and epithelial layers against an electrochemical gradient, requiring the expenditure of metabolic energy.	Active Transport,Uphill Transport,Active Biological Transport,Biologic Transport, Active,Transport, Active Biological,Active Biologic Transport,Transport, Active,Transport, Active Biologic,Transport, Uphill
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
D013050	Spectrometry, Fluorescence	Measurement of the intensity and quality of fluorescence.	Fluorescence Spectrophotometry,Fluorescence Spectroscopy,Spectrofluorometry,Fluorescence Spectrometry,Spectrophotometry, Fluorescence,Spectroscopy, Fluorescence