The acid dissociation constant (pKa) is among the most frequently used physicochemical parameters, and its determination is of interest to a wide range of research fields. We present a brief introduction on the conceptual development of pKa as a physical parameter and its relationship to the concept of the pH of a solution. This is followed by a general summary of the historical development and...

An acid dissociation constant of tetrabromophenolphthalein ethyl ester (TBPE) was determined through the measurement of electrophoretic mobility by capillary zone electrophoresis (CZE). Although TBPE is degradable in acidic pH region and it gradually degraded at pH conditions around and below its pKa values in the time scale of the CZE measurement, equilibrium species of interest were detected ...

The dissociation kinetics of cooperatively bound bacteriophage T4 gene 32 protein from a variety of single-stranded homopolynucleotides has been investigated by stopped-flow techniques. Irreversible dissociation of the complexes was induced by rapidly increasing the salt concentration and monitoring the increase in tryptophan fluorescence upon dissociation of the gene 32 protein. The dependence...

The isolation and cloning of the cDNA coding for myoglobin (Mb) from the mollusc Aplysia limacina is reported here. Five amino acid differences from the previously published protein sequence have been found in positions 22, 26, 27, 77 and 80 by back transplanting the cDNA; some of these may be relevant for overall structure stabilization in this Mb. High-level expression of the holoprotein in E...

The biopharmaceutical profile of a compound depends directly on the dissociation constants of its acidic and basic groups, commonly expressed as the negative decadic logarithm pKa of the acid dissociation constant (Ka). The acid dissociation constant (also protonation or ionization constant) Ka is an equilibrium constant defined as the ratio of the protonated and the deprotonated form of a comp...

According to experiments reported by Field and O'Brien,I acidification of normal human adult hemoglobin (Hb A) from pH 6 to pH 3.5 is accompanied by a progressive, reversible decrease in sedimentation constant, together with an increase in translational diffusion constant. These findings were interpreted as showing the presence of a rapidly reversible, hydrogen-ion-dependent dissociation of Hb ...

The influence of co-ions on the adsorption properties two surfactants: ABS (dodecylbenzene sulfonic acid) and its sodium salt ABSNa50 in aqueous systems, has been studied discussed. On basis experimental measurements equilibrium dynamic surface tension, a series parameters were determined, such as critical micelle concentration (CMC), parameters, diffusion coefficients, micellar dissociation co...