The cation binding characteristics of the mutant E327A formed in the sheep al isoform of the Na+,K+-ATPase were examined using [3H]ouabain binding as a function of monovalent cation concentrations. Equilibrium competition binding assays in the presence of Mg2+, inorganic phosphate and various amounts of unlabelled ouabain indicated that both wild-type sheep al protein and the E327A mutant expre...

The vacuole-type ATPases (V-ATPases) are proton pumps in various intracellular compartments of eukaryotic cells. Prokaryotic V-ATPase of Enterococcus hirae, closely related to the eukaryotic enzymes, provides a unique opportunity to study ion translocation by V-ATPases because it transports Na(+) ions, which are easier to detect by x-ray crystallography and radioisotope experiments. The purifie...

MacLeod et al. (1954) noted that a number of strains of bacteria from the marine environment which can not grow on fresh water media are dependent upon Na+, K+, and Mg++, whereas several similar isolates capable of growth on fresh water media have no Na+ dependence. A subsequent investigation of the effect of these metal ions on the viability in storage and the activity of oxidative systems of ...

We have used ab initio molecular dynamics (AIMD) simulations to study the interaction of water with the NaCl surface. As expected, we find that water forms several ordered hydration layers, with the first hydration layer having water molecules aligned so that oxygen atoms are on average situated above Na sites. In an attempt to understand the dissolution of NaCl in water, we have then combined ...

abstract: warfarin is the most commonly used oral anticoagulant drug in clinical practice with extreme inter and intra-individual variation in pharmacokinetic properties. na valproate, a broad spectrum anticonvulsant agent, is best known for its enzyme inhibition properties and also displacement of protein binding sites. interaction between warfarin and psychotropic drugs including valproate ar...

The asymmetric unit of the polymeric title compound, [Na(2)(C(20)H(13)O(5)P)(C(2)H(6)O)(H(2)O)(5)](n), consists of two Na(I) ions, one 2'-hydr-oxy-1,1'-binaphthyl-2-yl phosphate anion, one ethanol ligand and five water molecules of crysallization. Each Na(I) ion has a distorted octa-hedral coordination geometry. The phosphate anion coordinates to one Na(I) ion and the ethanol mol-ecule coordina...

Active transport of glutamate by Escherichia coli K-12 requires both Na(+) and K(+) ions. Increasing the concentration of Na(+) in the medium results in a decrease in the K(m) of the uptake system for glutamate; the capacity is not affected. Glutamate uptake by untreated cells is not stimulated by K(+). K(+)-depleted cells show a greatly reduced capacity for glutamate uptake. Preincubation of s...

Understanding the mechanism of ion permeation across lipid bilayers is key to controlling osmotic pressure and developing new ways of delivering charged, drug-like molecules inside cells. Recent reports suggest ion-pairing as the mechanism to lower the free energy barrier for the ion permeation in disagreement with predictions from the simple electrostatic models. In this paper we quantify the ...

AIMS Contraction of the heart is regulated by electrically evoked Ca(2+) transients (CaTs). H(+) ions, the end products of metabolism, modulate CaTs through direct interactions with Ca(2+)-handling proteins and via Na(+)-mediated coupling between acid-extruding proteins (e.g. Na(+)/H(+) exchange, NHE1) and Na(+)/Ca(2+) exchange. Restricted H(+) diffusivity in cytoplasm predisposes pH-sensitive ...

The mechanism by which the intra-erythrocytic form of the human malaria parasite, Plasmodium falciparum, extrudes H ions and thereby regulates its cytosolic pH (pHi), was investigated using saponin-permeabilized parasitized erythrocytes. The parasite was able both to maintain its resting pHi and to recover from an imposed intracellular acidification in the absence of extracellular Na, thus ruli...