Globule-coil transition of denatured globular protein investigated by a microwave dielectric technique

Abstract

A mechanism for the gel–glass transition of denatured globular protein has been explained from the viewpoint of the globule–coil transition with microwave dielectric measurements using a time domain reflectometry (TDR) method. Boiled egg white, which is an aqueous gel of egg white prepared by heat treatment at 100°C, becomes a glass on drying. In the gel state, the relaxation processes corresponding to the orientation of bulk water and the micro‐Brownian motion of peptide chains of denatured protein were observed around 10 GHz and 10 MHz, respectively. When the gel–glass transition occurred, the relaxation strength for bulk water decreased rapidly as evaporation and breaking of water structure occurred. Simultaneously, the relaxation strength for micro‐Brownian motion increased abruptly, as the structure of globular protein varied from globule state to coiled state. It is considered that the protein molecule spreads out and takes up a coiled state by reductions of hydrophobic and hydrophilic interactions of the globular protein. These reductions occur through a decrease in the amount of water. © 2000 John Wiley & Sons, Inc. Biopoly 54: 388–397, 2000

Slow and fast dynamics in glycerol–water mixtures

“…3 and s v values are also very close to each other in this concentration range. The estimated values of glass-transition temperature (T g ) from BDS data by extrapolations of s max = 100 s [32,33] in Fig. 3 were in good agreement with T g obtained by DSC measurements, as shown Fig.…”

Physical Meanings of Fractal Behaviors of Water in Aqueous and Biological Systems with Open-Ended Coaxial Electrodes

“…In our previous studies, the middle area between those two areas has been offered for gel systems such as poly (acryl amide) (PAAm) aqueous gels [38,39] and glass egg [40], which is obtained from the drying process of thermal-denatured egg white gel. However, the adequacy of the region allocated for gel systems needs to be reconsidered in the present work because of a few examples so far.…”

Ultrasonic Storage Modulus as a Novel Parameter for Analyzing Protein-Protein Interactions in High Protein Concentration Solutions: Correlation with Static and Dynamic Light Scattering Measurements

“…In solutions, additional relaxation processes involving solute-solute and solute-solvent interactions exist that are associated with their characteristic t. Rotational and translation diffusion of protein molecules in solutions, segmental motions, and conformational rearrangements occur on the timescale of 10 ÿ7 -10 ÿ9 s (20)(21)(22)(23)(24)(25)(26). Relaxation of bound water occurs around 10 ÿ10 -10 ÿ11 s (27). The timescale of these relaxations is governed not only by temperature but also by the solvent and solute concentration.…”