Two-Dimensional Infrared Correlation Spectroscopy Study of the Aggregation of Cytochrome c in the Presence of Dimyristoylphosphatidylglycerol

Two-dimensional infrared correlation spectroscopy (2D-IR) was used in this study to investigate the aggregation of cytochrome c in the presence of dimyristoylphosphatidylglycerol. The influence of temperature on the aggregation has been evaluated by monitoring the intensity of a band at 1616 cm −1,...

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Bibliographic Details
Published in:Biophysical journal 2001-07, Vol.81 (1), p.305-312
Main Authors: Paquet, Marie-Josée, Laviolette, Mario, Pézolet, Michel, Auger, Michèle
Format: Article
Language:English
Subjects:
Biology
Cytochrome c Group - chemistry
Cytochrome c Group - metabolism
Hot Temperature
Phosphatidylglycerols - chemistry
Phosphatidylglycerols - metabolism
Physics
Protein Binding
Protein Denaturation
Proteins
Spectroscopy, Fourier Transform Infrared
Spectrum analysis
Temperature
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Summary:Two-dimensional infrared correlation spectroscopy (2D-IR) was used in this study to investigate the aggregation of cytochrome c in the presence of dimyristoylphosphatidylglycerol. The influence of temperature on the aggregation has been evaluated by monitoring the intensity of a band at 1616 cm −1, which is characteristic of aggregated proteins, and the 2D-IR analysis has been used to determine the various secondary structure components of cytochrome c involved before and during its aggregation. The 2D-IR correlation analysis clearly reveals for the first time that aggregation starts to occur between nearly native proteins, which then unfold, yielding to further aggregation of the protein. Later in the aggregation process, the formation of intermolecular bonds and unfolding of the α-helices appear to be simultaneous. These results lead us to propose a two-step aggregation process. Finally, the results obtained during the heating period clearly indicate that before the protein starts to aggregate, there is a loosening of the tertiary structure of cytochrome c, resulting in a decrease of the β-sheet content and an increase of the amount of β-turns. This study clearly demonstrates the potential of 2D-IR spectroscopy to investigate the aggregation of proteins and this technique could therefore be applied to other proteins such as those involved in fibrilogenesis.
ISSN:0006-3495
1542-0086
DOI:10.1016/S0006-3495(01)75700-1