The ANS- (1-anilino-8-naphthalene sulfonate) anion is strongly, dominantly bound to cationic groups of water-soluble proteins and polyamino acids through ion pair formation. This mode of ANS- binding, broad and pH dependent, is expressed by the quite rigorous stoichiometry of ANS- bound with respect to the available summed number of H+ titrated lysine, histidine, and arginine groups. By titrati...

The objective of this study was to examine the effect of ion-pair complexation with endogenous bile salts on the transport of a quarternary ammonium organic cationic (OC) drug, berberine, across the Caco-2 and LLC-PK1 cell monolayers. The basolateral-to-apical (BL-AP) transport of berberine in Caco-2 cells was temperature dependent and 10-fold higher than that of the apical-to-basolateral (AP-B...

A scheme to model the dependence of a solute redox potential on the supporting electrolyte is proposed, and the results are compared to experimental observations and other reported theoretical models. An improved agreement with experiment is exhibited if the effect of the supporting electrolyte on the redox potential is modeled through a concentration change induced via ion pair formation with ...

SSSAJ: Volume 74: Number 5 • September–October 2010 Soil Sci. Soc. Am. J. 74:1568–1576 Published online 3 Aug. 2010 doi:10.2136/sssaj2009.0161 Mention of a specifi c brand of equipment does not imply an endorsement by the University of Hawaii or the authors. Received 28 Apr. 2009. *Corresponding author ([email protected]). © Soil Science Society of America, 5585 Guilford Rd., Madison WI 53711 US...

A novel method for separating fulvic acid (FA) from soil extracts is proposed. The FA, defined as the acid-soluble fraction of an alkaline extract of soil, was separated based on the precipitation of an ion-pair with a cationic surfactant, such as domiphen bromide. The precipitate was dissolved in aqueous HCl to produce H+ -type FA and a surfactant chloride (SUR-Cl). SUR-Cl, in the aqueous solu...

Chirality is a fundamental property intrinsic to many supramolecular systems.2 Helical assemblies are inherently chiral, regardless of the stereotopic information contained within the individual building blocks.3-5 Metallo-supramolecular helicates, assembled from achiral ligands and metal centers, form racemic mixtures of clockwise and counterclockwise structures in which all the metal centers ...

Sea spray aerosols (SSA) are known to have an organic coating that is mainly composed of fatty acids. In this study, the effect of pH and salt on the stability and organization of a palmitic acid (PA) monolayer is investigated by surface vibrational spectroscopy and molecular dynamics simulations. Results indicate that alkyl chain packing becomes more disordered as the carboxylic headgroup beco...

A simple, sensitive and rapid spectrophotometric method was developed and validated for the determination of two skeletal muscle relaxants namely, tizanidine hydrochloride (I) and orphenadrine citrate (II) in pharmaceutical formulations. The proposed method is based on the formation of a binary complex between the studied drugs and eosin Y in aqueous buffered medium (pH 3.5). Under the optimum ...

The S4 transmembrane segments of voltage-gated ion channels move outward on depolarization, initiating a conformational change that opens the pore, but the mechanism of S4 movement is unresolved. One structural model predicts sequential formation of ion pairs between the S4 gating charges and negative charges in neighboring S2 and S3 transmembrane segments during gating. Here, we show that pair...

Levofloxacin (LFX), an antimicrobial agent has been detected by using picric acid (PA) as an anionic reagent in aqueous medium. On mixing the reactants in distilled water yellow colored product is separated within two minutes which was found to be an ionassociation complex (LFX-PA) of both the reactants. Spectroscopic and voltammetric studies were carried out to explain the interaction between ...