Submolecular Unfolding Units of Pseudomonas aeruginosa Cytochrome c551

• Published in: Journal of biological inorganic chemistry Vol. 13; no. 5; pp. 837 - 845
• Main Authors: Michel, Lea V., Bren, Kara L.
• Format: Journal Article
• Language: English
• Published: 08-04-2008
• ISSN: 0949-8257; 1432-1327
• DOI: 10.1007/s00775-008-0370-y

Hydrogen exchange (HX) rates for backbone amide protons of oxidized
Pseudomonas aeruginosa
cytochrome
c
551
(
Pa
-cyt
c
) have been measured in the presence of low concentrations of the denaturant guanidine hydrochloride. Analysis of the data has allowed identification of submolecular unfolding units known as foldons. The highest energy foldon bears similarity to the proposed folding intermediate for
Pa
-cyt
c
. Parallels are seen to the foldons of the structurally homologous horse cyt
c
, although the heme axial methionine-bearing loop has greater local stability in
Pa
-cyt
c
, in accord with previous folding studies. Regions of low local stability are observed to correspond with regions that interact with redox partners, providing a link between foldon properties and function.