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Effect of protein charge on the generation of aggregation-prone conformers

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Author: Broersen, K. · Weijers, M. · Groot, J.de · Hamer, R.J. · Jongh, H.H.J.de
Type:article
Date:2007
Institution: TNO Kwaliteit van Leven
Source:Biomacromolecules, 5, 8, 1648-1656
Identifier: 239952
doi: doi:10.1021/bm0612283
Keywords: Nutrition · Food technology · Chemical modification · Conformations · Denaturation · Electrostatics · Methylation · Proteins · Temperature · Aggregation kinetics · Conformers · Electrostatic repulsive forces · Ovalbumin · Biomolecules · ovalbumin · article · conformational transition · controlled study · denaturation · electricity · heating · methylation · nonhuman · physical chemistry · priority journal · protein aggregation · protein engineering · surface charge · Animals · Electrostatics · Heat · Kinetics · Ovalbumin · Protein Denaturation · Protein Folding · Urea

Abstract

This study describes how charge modification affects aggregation of ovalbumin, thereby distinguishing the role of conformational and electrostatic stability in the process. Ovalbumin variants were engineered using chemical methylation or succinylation to obtain a range of protein net charge from -1 to -26. Charge modification significantly affected the denaturation temperature. From urea-induced equilibrium denaturation studies, it followed that unfolding proceeded via an intermediate state. However, the heat-induced denaturation process could still be described as a two-state irreversible unfolding transition, suggesting that the occurrence of an intermediate has no influence on the kinetics of unfolding. By monitoring the aggregation kinetics, the net charge was found not to be discriminative in the process. It is concluded that the dominant factor determining ovalbumin aggregation propensity is the rate of denaturation and not electrostatic repulsive forces. © 2007 American Chemical Society.