The variety of methods used to identify the structural determinants of anion selectivity in the cystic fibrosis transmembrane conductance regulator Cl(-) channel has made it difficult to assemble the data into a coherent framework that describes the three-dimensional structure of the pore. Here, we compare the relative importance of sites previously studied and identify new sites that contribut...

studies by the us salinity laboratory, using gapon rule, led to the value of 0.01475 (mmol l-1)-0.5for the modified gapon selectivity coefficient (k'g). nevertheless, the results of subsequent research reveled that k'g isn’t constant and could take on a wide range of values depending on soil properties. the aim of this study was to determine the relationship between exchangeable sodiu...

a simple and sensitive extractive- spectrophotometric method for thedeterrnination of trace amounts of vanadium(v) is reported. the method is based on the quantitative extraction of the anion complex of v(v) with 4-(2-pyridy1azo)-resorcinol with tetrabutylammonium perchlorate into chloroform, followed by spectrophotometric measurements at 554 nm. beer's law is obeyed over the concentration...

Cyclic nucleotide-gated (CNG) channels play a critical role in olfactory and visual transduction. Site-directed mutagenesis and inside-out patch-clamp recordings were used to investigate ion permeation and selectivity in two mutant homomeric rat olfactory CNGA2 channels expressed in HEK293 cells. A single point mutation of the negatively charged pore loop (P-loop) glutamate (E342) to either a p...

A series of linear peptide based anion receptors, in which the distance between the bis[zinc(II)dipicolylamine] binding sites and the peptide backbone was varied systematically, was prepared and their anion binding ability was investigated using indicator displacement assays. Shortening the distance between the binding site and the peptide backbone was found to enhance both the receptor affinit...

Solid-phase extraction method followed by direct UV spectrophotometry at 264 nm was developed and applied for the selective ibuprofen determination in two-component formulation of ibuprofen and pseudoephedrine-HCl, combined powder which contains ibuprofen in the form of salt with L-arginine and 10% ibuprofen cream. Procedures for ibuprofen determination in complex pharmaceutical preparations by...

Twelve different porins from the gram-negative bacteria Escherichia coli, Salmonella typhimurium, Pseudomonas aeruginosa, and Yersinia pestis were reconstituted into lipid bilayer membranes. Most of the porins, except outer membrane protein P, formed large, water-filled, ion-permeable channels with a single-channel conductance between 1.5 and 6 nS in 1 M KCl. The ions used for probing the pore ...

Extraordinary selectivity is crucial to all proton-conducting molecules, including the human voltage-gated proton channel (hHV1), because the proton concentration is >10(6) times lower than that of other cations. Here we use "selectivity filter scanning" to elucidate the molecular requirements for proton-specific conduction in hHV1. Asp(112), in the middle of the S1 transmembrane helix, is an e...

oxime extractants 3-tert-butyl-2-hydroxy-5-methyl benzaldehyde oxime (hl1) and 3-tert-butyl-2-hydroxy-5-methoxy benzaldehyde oxime (hl2) were synthesized and characterized by conventional spectroscopic methods. suitable lipophilic nature of the prepared extractants allowed examining the ability of these molecules for extraction-separation of copper from its mixture with normally associated meta...