Thermodynamics and kinetics of the pressure unfolding of phosphoglycerate kinase

Szabolcs Osváth, Manh Quynh Luu, László Smeller

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Abstract

Due to the relationship between compressibility and volume fluctuations, high-pressure studies provide vital insight into protein dynamics and function. Most high-pressure experiments were performed on small and fast folding proteins or model peptides. Here we show that a detailed kinetic study is necessary to extract reliable information from the high-pressure-induced structural conversion of large, slowly folding proteins. The pressure-jump unfolding kinetics of yeast phosphoglycerate kinase was recorded at pressures between 50 and 150 MPa. The time dependence of the conformational state of the protein was followed by tryptophan fluorescence measurements from 30 s to 2 h. The observed changes were described by a three-state model, and the volume change and the activation volume as well as the midpoint pressure of the transitions between the folded, intermediate, and unfolded states were determined. An interesting feature of the pressure unfolding of phosphoglycerate kinase was that the unfolding process speeds up with increasing pressure, which is the consequence of negative activation volumes for the folded → intermediate, intermediate → unfolded, and unfolded → intermediate transitions.

Original languageEnglish
Pages (from-to)10146-10150
Number of pages5
JournalBiochemistry
Volume48
Issue number42
DOIs
Publication statusPublished - Oct 27 2009

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ASJC Scopus subject areas

  • Biochemistry

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