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Counteraction of trehalose on urea-induced protein unfolding: Thermodynamic and kinetic studies

Paper ID Volume ID Publish Year Pages File Format Full-Text
3275 162 2013 9 PDF Available
Title
Counteraction of trehalose on urea-induced protein unfolding: Thermodynamic and kinetic studies
Abstract

•Urea-induced protein unfolding in 8.00 mol/L urea reveals two observable phases.•Trehalose inhibits the urea-induced denaturation of ferricytochrome c at pH 7.0.•At trehalose concentrations > 0.30 mol/L, the unfolding pathway shows a single phase.•The observable unfolding rates decrease with increasing trehalose concentration.

Urea-induced protein denaturation can be effectively inhibited by trehalose, but the thermodynamic and kinetic behaviors are still unclear. Herein, the counteraction of trehalose on urea-induced unfolding of ferricytochrome c was studied. Thermodynamic parameters for the counteraction of trehalose were derived based on fluorescence spectroscopic data. Then the kinetics was emphatically investigated by stopped-flow fluorescence spectroscopy. Urea-induced unfolding of ferricytochrome c in 8.00 mol/L urea solution reveals two observable phases, including fast and slow phases following a burst phase. Trehalose has little influence on the burst phase amplitude. Nevertheless, the observable unfolding pathway is significantly affected by trehalose. At lower trehalose concentrations (<0.20 mol/L) in 8.00 mol/L urea, the unfolding pathways still keep to show two phases. However, the rate constant and amplitude for the fast phase diminish with increasing trehalose concentration. In contrast, the rate constant for the slow phase shows only a slight change with a significant increase of the amplitude. At higher trehalose concentrations (>0.30 mol/L), the unfolding pathway is transformed into a single slow phase. The rate constant and amplitude for the single phase also decrease with increasing trehalose concentration. The studies are expected to help our understanding of trehalose effects on protein stability.

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Keywords
F, fluorescence intensity; F∞, fluorescence intensity at infinite time; Ai, amplitude of the ith phase; ki, rate constant of the ith phase; t, time; F350 nm280 nm, fluorescence intensity at an emission wavelength of 350 nm and an excitation wavelength of
First Page Preview
Counteraction of trehalose on urea-induced protein unfolding: Thermodynamic and kinetic studies
Publisher
Database: Elsevier - ScienceDirect
Journal: Biochemical Engineering Journal - Volume 79, 15 October 2013, Pages 120–128
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering