Table of Contents
New Journal of Science
Volume 2014, Article ID 484538, 28 pages
http://dx.doi.org/10.1155/2014/484538
Review Article

Cytochrome c: A Multifunctional Protein Combining Conformational Rigidity with Flexibility

Department of Chemistry, Drexel University, 3141 Chestnut Street, Philadelphia, PA 19104, USA

Received 26 February 2014; Accepted 3 June 2014; Published 22 July 2014

Academic Editor: Hamid Mobasheri

Copyright © 2014 Reinhard Schweitzer-Stenner. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Cytochrome has served as a model system for studying redox reactions, protein folding, and more recently peroxidase activity induced by partial unfolding on membranes. This review illuminates some important aspects of the research on this biomolecule. The first part summarizes the results of structural analyses of its active site. Owing to heme-protein interactions the heme group is subject to both in-plane and out-of-plane deformations. The unfolding of the protein as discussed in detail in the second part of this review can be induced by changes of pH and temperature and most prominently by the addition of denaturing agents. Both the kinetic and thermodynamic folding and unfolding involve intermediate states with regard to all unfolding conditions. If allowed to sit at alkaline pH (11.5) for a week, the protein does not return to its folding state when the solvent is switched back to neutral pH. It rather adopts a misfolded state that is prone to aggregation via domain swapping. On the surface of cardiolipin containing liposomes, the protein can adopt a variety of partially unfolded states. Apparently, ferricytochrome c can perform biological functions even if it is only partially folded.