Globule-coil transition of denatured globular protein investigated by a microwave dielectric technique.
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 degrees 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.
Hayashi
Y
Y
Department of Physics, Tokai University, Hiratsuka-shi, Kanagawa, 259-1292, Japan.
Miura
N
N
Shinyashiki
N
N
Yagihara
S
S
Mashimo
S
S
D000818:Animals; D002152:Calorimetry, Differential Scanning; D004529:Egg White; D004563:Electrochemistry; D005782:Gels / Q000737:chemistry; D008872:Microwaves; D009038:Motion; D011487:Protein Conformation / Q000187:drug effects; D011489:Protein Denaturation; D011506:Proteins / Q000737:chemistry*; D014867:Water / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology
D005782:Gels; D011506:Proteins; D014867:Water