Protein/polyelectrolyte coacervation: Investigating its occurrence in the lysozyme- carboxymethylcellulose system.

The coacervation of carboxymethylcellulose (CMC) and hen egg white lysozyme (HEWL) was investigated. The work focused on the effects of pH, ionic strength, I, temperature, T, and mass fraction of the macromolecular components on the coacervation process by spectrophotometry, and on characteristics of the resulting coacervate phase by rheology in the linear and non-linear regimes. Coacervation was found to be highest at HEWL mass fraction ≈0.

Non-ideal behavior of binary aqueous mixtures of some urea derivatives and their capacity to induce lysozyme gelation.

The urea derivatives, namely, ethylurea (EU), 1,3 dimethylurea (1,3-DMU) and 1,1 diethylurea (1,1-DEU), in the limiting regions of their solubilities in water, and tetramethylurea (TMU) at w≥0.65 were investigated in relation to their capacity of inducing hen egg white lysozyme (HEWL) physical (non-covalent) gelation. Protein transparent gels were generated out of TMU/HO and 1,1-DEU/HO, respectively, whereas an intensively turbid gel resulted from sol-gel transition taking place in EU/HO.

Chemistry and applications of polysaccharide solutions in strong electrolytes/dipolar aprotic solvents: an overview.

Biopolymers and their derivatives are being actively investigated as substitutes for petroleum-based polymers. This has generated an intense interest in investigating new solvents, in particular for cellulose, chitin/chitosan, and starch. This overview focuses on recent advances in the dissolution and derivatization of these polysaccharides in solutions of strong electrolytes in dipolar aprotic solvents.

Dynamic viscosity of implantable autologous materials into the vocal fold.

Objective: To compare the dynamic viscosity (DV) of superficial layer of temporalis fascia (SLTF) with that of other biological tissues traditionally used for vocal fold implants to treat vocal fold rigidity.

Study Design: Experimental.

Method: Measurement of DV of samples of SLTF, deep layer of temporalis fascia (DLTF), and abdominal fat of 12 cadavers.

DMSO-induced denaturation of hen egg white lysozyme.

We report on the size, shape, structure, and interactions of lysozyme in the ternary system lysozyme/DMSO/water at low protein concentrations. Three structural regimes have been identified, which we term the "folded" (0 < φ(DMSO) < 0.7), "unfolded" (0.

Measurement of the viscoelastic properties of the vocal folds.

Objectives: Studies of the viscoelastic properties of the vocal folds are normally performed with rheometers that use parallel plates whose interplate space is usually arbitrarily assigned a fixed value. In tissues subject to variation of thickness between samples, fixed gaps could result in different compressions, compromising the comparison among them. We performed an experimental study to determine whether different compressions can lead to different results in measurements of dynamic viscosity (DV) of vocal fold samples.

Solvent-induced lysozyme gels: effects of system composition and temperature on structural and dynamic characteristics.

The gelation process of lysozyme in water/tetramethylurea in the presence of salt was investigated as a function of temperature and system composition by rheology, infrared spectroscopy, and microcalorimetry. Times and temperatures of gelation were determined from the variation of the storage (G') and loss (G'') moduli. It was found that gelation times follow exponential decays with both protein and tetramethylurea (TMU) concentrations and with temperature.

Low-resolution 1H spin-spin relaxation of n-decane/water emulsions stabilized by beta-casein.

A low-resolution 1H NMR relaxometry study on the dynamics of an n-decane/water emulsion stabilized by beta-casein is presented. Spin-spin (transverse) relaxation time constants (T2) were used to assess relative mobilities of emulsion components, by a selective deuteration procedure. Data analysis allowed the emulsion investigated to be described by a heterogeneous collection of dynamically distinct populations.

Solvent-induced lysozyme gels: rheology, fractal analysis, and sol-gel kinetics.

In this work, the gelation kinetics and fractal character of lysozyme gel matrices developed in tetramethylurea (TMU)-water media were investigated. Gelation times were determined from the temporal crossover point between the storage, G', and loss, G'', moduli, as a function of the binary solvent composition and of protein concentration. The inverse dependence of the upper limit of the linear viscoelastic region (gamma0) on protein concentration indicate that the lysozyme gels belong to the "strong link" kind, a gel category where interparticle links are stronger than intraparticle ones.

Gliadin effect on fluctuation properties of phospholipid giant vesicles.

Gliadin is a fraction of wheat gluten, a protein supramolecular complex known for its remarkable and biotechnologically relevant viscoelastic properties. Very high molecular mass characterise these systems, thus hindering high-resolution structural investigations. It is known, however, that these proteins comprise rather extended, extensively interassociated structures, which respond for their peculiar mechanical behaviour.

Lysozyme viscoelastic matrices in tetramethylurea/water media: a small angle X-ray scattering study.

Semi-solid viscoelastic matrices produced out of lysozyme in organic/aqueous media [tetramethylurea (TMU)/water] were characterized by small angle X-ray scattering (SAXS). The scattering curves were modeled in their form and interference factors. Radii of gyration of scattering particles were found to undergo a dramatic increase from 14 A in water to approximately 44 A in the matrices.

Rheological study on lysozyme/tetramethylurea viscoelastic matrices.

Rheological properties of lysozyme viscoelastic matrices resulting from a sol-gel transition taking place in organic/aqueous media at room temperature were investigated. Gel-like structures, of transparent appearance, developed out of lysozyme (5.0 mmol/dm(3)) dispersed in tetramethylurea (TMU)/water binary mixtures, at TMU mass fraction (w) ranging from w(TMU) 0.