2009 Volume 73 Issue 2 Pages 366-371
The stability of the oxidized and reduced forms of three homologous cytochromes c from two thermophiles and one mesophile was systematically monitored by means of Soret absorption measurements in the presence of various concentrations of a denaturant, guanidine thiocyanate, at pH 7.0 at 25 °C. Thermophilic Hydrogenobacter thermophilus cytochrome c552 was the most stable in both redox states, followed by moderately thermophilic Hydrogenophilus thermoluteolus cytochrome c552, and then mesophilic Pseudomonas aeruginosa cytochrome c551. Further stability and electrochemical analysis of the three proteins and the reciprocal variants, which exhibited a different hydrophobic interaction with the heme, showed that the one with the higher stability in both redox states had the lower redox potential. Consequently, these cytochromes c probably adapted to the cellular environments of the original bacteria with correlated stability and redox potential constraints, which are in part regulated by the hydrophobicity around the heme.
This article cannot obtain the latest cited-by information.