The activity of biocatalysts in nonaqueous solvents is related to the interaction of organic solvents with cells or enzymes. The behavior of proteins is strongly dependent on the protonation state of their ionizable groups, which ionization constants are greatly affected by the solvent. Due to the weak ionizing and dissociating powers of common organic solvents, the charge of the protein will c...

Amphiphilic-like carbon dots bearing ionizable carboxylate groups and hydrophobic alkyl chains entrap molecules solubilize them in aqueous systems. In nanomedicine they can be used as drug delivery systems phototherapeutic agents.

We report a novel self-assembling system of amphiphilic oligopeptides composed of alternating hydrophobic and ionizable amino-acid residues. Three types of peptides, AD12, AE12 and AK12, were prepared as building blocks for this model system. These peptides formed helical conformations in low-concentration solutions, but these peptides adopted b-sheet structures and precipitated in highly conce...

The vast majority of membrane proteins are anchored to biological membranes through hydrophobic α-helices. Sequence analysis of high-resolution membrane protein structures show that ionizable amino acid residues are present in transmembrane (TM) helices, often with a functional and/or structural role. Here, using as scaffold the hydrophobic TM domain of the model membrane protein glycophorin A ...

Six green leafy vegetables and herbs - spinach, amaranth, bengal gram, cauliflower, mint, coriander and carrots - were analyzed for moisture, protein, ascorbic acid, beta-carotene, total iron, ionizable iron (as % of total iron) in vitro iron (% of total iron), copper, manganese and zinc. Moisture content of the leaves and carrots varied from 75.1 percent (bengal gram) to 95.4 percent (carrot) ...

iii Abstract Solubility Modelling in Condensed Matter. Dielectric Continuum Theory and Nonlinear Response. Lars Sandberg, Theoretical Biophysics Group, Department of Physics, Royal Institute of Technology, SE-106 91 Stockholm, SWEDEN.Solubility Modelling in Condensed Matter. Dielectric Continuum Theory and Nonlinear Response. Lars Sandberg, Theoretical Biophysics Group, Department of Physics, R...

Previously we reported that Lys, Asp, and Glu residues at positions 66 and 92 in staphylococcal nuclease (SNase) titrate with pK(a) values shifted by up to 5 pK(a) units in the direction that promotes the neutral state. In contrast, the internal Lys-38 in SNase titrates with a normal pK(a). The crystal structure of the L38K variant shows that the side chain of Lys-38 is buried. The ionizable mo...

The role of pH in regulating biological activity is ubiquitous, and understanding pH-mediated activity has traditionally relied on analyzing static biomolecular structures of highly populated ground states solved near physiological pH. However, recent advances have shown the increasing importance of transiently populated states, the characterization of which is extremely challenging but made pl...

We have characterized the guanidine-induced unfolding of both yeast and bovine ubiquitin at 25 degrees C and in the acidic pH range on the basis of fluorescence and circular dichroism measurements. Unfolding Gibbs energy changes calculated by linear extrapolation from high guanidine unfolding data are found to depend very weakly on pH. A simple explanation for this result involves the two follo...

The static structure factor S(q) is measured for a set of deionized latex dispersions with different numbers of ionizable surface groups per particle and similar diameters. For a given volume fraction, the height of the main peak of S(q), which is a direct measure of the spatial ordering of latex particles, does not increase monotonically with the number of ionizable groups. This behaviour cann...