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Globule–coil transition of denatured globular protein investigated by a microwave dielectric technique
Author(s) -
Hayashi Yoshihito,
Miura Nobuhiro,
Shinyashiki Naoki,
Yagihara Shin,
Mashimo Satoru
Publication year - 2000
Publication title -
biopolymers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.556
H-Index - 125
eISSN - 1097-0282
pISSN - 0006-3525
DOI - 10.1002/1097-0282(200011)54:6<388::aid-bip30>3.0.co;2-k
Subject(s) - globular protein , chemistry , relaxation (psychology) , dielectric , glass transition , chemical physics , crystallography , analytical chemistry (journal) , chromatography , organic chemistry , polymer , materials science , psychology , social psychology , optoelectronics
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