The folding energy landscape and free energy excitations of cytochrome c

P. Weinkam, J. Zimmermann, F.E. Romesberg, P. Wolynes, Acc. Chem. Res. (2010) 43:652-660.
pubpic2010weinkamAt low pH, the experimentally observed folding sequence of cyt c deviates from that at pH 7 and from models with perfectly funneled energy landscapes. We account for these alternative folding pathways using complex models that begin from native structure-based terms and also add the chemical frustration that arises because some regions of the protein are destabilized more than others due to the heterogeneous distribution of titratable residues that are protonated at low pH.