We find that moderate cationic selectivity of the general bacterial porin OmpF in sodium and potassium chloride solutions is inversed to anionic selectivity in concentrated solutions of barium, calcium, nickel, and magnesium chlorides. To understand the origin of this phenomenon, we consider several factors, which include the binding of divalent cations, electrostatic and steric exclusion of di...

The formation of water-insoluble glucan by extracellular glucosyltransferase from Streptococcus mutans 6715 found to be greatly stimulated by various mono- or divalent cations. An enzyme preparation, obtained by ethanol fractionation, was able to catalyze the formation of water-insoluble glucan from sucrose in the presence of monovalent cations above 100mM or divalent cations above 20 mM at neu...

Electrophysiological characterization of large protein channels, usually displaying multi-ionic transport and weak ion selectivity, is commonly performed at physiological conditions (moderate gradients of KCl solutions at decimolar concentrations buffered at neutral pH). We extend here the characterization of the OmpF porin, a wide channel of the outer membrane of E. coli, by studying the effec...

Previous publications from this laboratory (1, 2) showed that Aureomycinl in low concentrations inhibited the formation of the corresponding arylamines from chloramphenicol’ and p-nitrobenzoic acid. The enzyme system which mediated these reductions was complex. A dicarboxylic acid (e.g. I-malic) served as the hydrogen donor and the hydrogen was transported via diphosphopyridine nucleotide. In a...

We have carried out an ab initio molecular dynamics study on the sulfur dioxide (SO2) solvation in 1-ethyl-3-methylimidazolium thiocyanate for which we have observed that both cations and anions play an essential role in the solvation of SO2. Whereas, the anions tend to form a thiocyanate- and much less often an isothiocyanate-SO2 adduct, the cations create a "cage" around SO2 with those groups...

Calixarenes are a readily available and important class of macrocycles in supramolecularchemistry. Calixarenes have generated considerable interest due to their basket shaped structureand as useful building blocks to synthesize selective receptors for the guest species, notably alkali,alkaline earth, lanthanide and transition metal cations. In this work studied on the complexingproperties of a ...

calixarenes are a readily available and important class of macrocycles in supramolecularchemistry. calixarenes have generated considerable interest due to their basket shaped structureand as useful building blocks to synthesize selective receptors for the guest species, notably alkali,alkaline earth, lanthanide and transition metal cations. in this work studied on the complexingproperties of a ...