Characterization of the protein unfolding processes induced by urea and temperature

Alessandro Guerini Rocco, Luca Mollica, Piero Ricchiuto, António M. Baptista, Elisabetta Gianazza, Ivano Eberini

Research output: Contribution to journalArticle

56 Citations (Scopus)

Abstract

Correct folding is critical for the biological activities of proteins. As a contribution to a better understanding of the protein (un)folding problem, we studied the effect of temperature and of urea on peptostreptococcal Protein L destructuration. We performed standard molecular dynamics simulations at 300 K, 350 K, 400 K, and 480 K, both in 10 M urea and in water. Protein L followed at least two alternative unfolding pathways. Urea caused the loss of secondary structure acting preferentially on the β-sheets, while leaving the α-helices almost intact; on the contrary, high temperature preserved the β-sheets and led to a complete loss of the a-helices. These data suggest that urea and high temperature act through different unfolding mechanisms, and protein secondary motives reveal a differential sensitivity to various denaturant treatments. As further validation of our results, replica-exchange molecular dynamics simulations of the temperature-induced unfolding process in the presence of urea were performed. This set of simulations allowed us to compute the thermodynamical parameters of the process and confirmed that, in the configurational space of Protein L unfolding, both of the above pathways are accessible, although to a different relative extent.

Original languageEnglish
Pages (from-to)2241-2251
Number of pages11
JournalBiophysical Journal
Volume94
Issue number6
DOIs
Publication statusPublished - 15 Mar 2008

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