Comparative Fourier transform infrared spectroscopy study of cold-, pressure-, and heat-induced unfolding and aggregation of myoglobin

Filip Meersman, László Smeller, Karel Heremans

Research output: Contribution to journalArticle

170 Citations (Scopus)

Abstract

We studied the cold unfolding of myoglobin with Fourier transform infrared spectroscopy and compared it with pressure and heat unfolding. Because protein aggregation is a phenomenon with medical as well as biotechnological implications, we were interested in both the structural changes as well as the aggregation behavior of the respective unfolded states. The cold- and pressure-induced unfolding both yield a partially unfolded state characterized by a persistent amount of secondary structure, in which a stable core of G and H helices is preserved. In this respect the cold- and pressure-unfolded states show a resemblance with an early folding intermediate of myoglobin. In contrast, the heat unfolding results in the formation of the infrared bands typical of intermolecular antiparallel β-sheet aggregation. This implies a transformation of α-helix into intermolecular β-sheet. H/2H-exchange data suggest that the helices are first unfolded and then form intermolecular β-sheets. The pressure and cold unfolded states do not give rise to the intermolecular aggregation bands that are typical for the infrared spectra of many heat-unfolded proteins. This suggests that the pathways of the cold and pressure unfolding are substantially different from that of the heat unfolding. After return to ambient conditions the cold- or pressure-treated proteins adopt a partially refolded conformation. This aggregates at a lower temperature (32°C) than the native state (74°C).

Original languageEnglish
Pages (from-to)2635-2644
Number of pages10
JournalBiophysical journal
Volume82
Issue number5
DOIs
Publication statusPublished - Jan 1 2002

ASJC Scopus subject areas

  • Biophysics

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