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Folding units govern the cytochrome c alkaline transition
Linh Hoang1, Haripada Maity, Mallela M G Krishna
1Department of Biochemistry and Biophysics, University of Pennsylvania School of Medicine, Philadelphia, PA 19104-6059, USA. lhoang@mail.upenn.edu
Journal of Molecular Biology
|July 24, 2003
Summary
The alkaline transition of cytochrome c involves protein structural switching. These structural changes are governed by the same unfolding reactions that control cytochrome c
Area of Science:
- Biochemistry
- Protein Dynamics
- Structural Biology
Background:
- The alkaline transition of cytochrome c serves as a model system for studying protein structural switching.
- This transition involves the displacement of the heme ligand by another group, leading to significant conformational changes.
Purpose of the Study:
- To investigate the kinetic phases and underlying structural rearrangements during the alkaline transition of cytochrome c.
- To elucidate the relationship between protein unfolding pathways and functional activities.
Main Methods:
- Utilized stopped-flow spectroscopy to monitor rapid kinetic events following a pH jump.
- Analyzed kinetic data to identify rate-limiting structural changes during the alkaline transition.
Main Results:
- Observed two distinct slow kinetic phases during the alkaline transition, indicating two rate-limiting structural changes.
- Demonstrated that these transitions are controlled by the same unfolding reactions governing the reversible unfolding of cytochrome c.
Conclusions:
- The cooperative folding-unfolding behavior of protein foldons underlies both folding pathways and functional activities.
- Protein structural switching, as exemplified by cytochrome c's alkaline transition, is intrinsically linked to its fundamental unfolding mechanisms.