title: Comparative solvent perturbation of horse heart cytochrome c and Rhodospirillum rubrum cytochrome c2.
abstract: The extent of exposure of heme to solvent in horse heart cytochrome c and Rhodospirillum rubrum c2 was investigated to determine whether a correlation exists between the properties of these oxidation-reduction proteins and their heme environments. Solvent perturbation absorption difference spectra were measured using ethylene glycol, glycerol, and sucrose at concentrations between 0 and 30%. Cytochrome c appears to exhibit a somewhat greater extent of heme exposure than cytochrome c2 for both the oxidized and reduced states. These results suggest that the lower oxidation-reduction potential of cytochrome c may in part be due to a greater extent of exposure of the heme. The oxidized state of both proteins appears to exhibit a greater exposure than that of the reduced state which is consistent with a more favorable environment for the charge on the ferric heme coordination center.
mesh_terms: D000818:Animals; D003574:Cytochrome c Group; D005026:Ethylene Glycols; D005990:Glycerol; D006418:Heme; D006736:Horses; D009206:Myocardium / Q000201:enzymology*; D010084:Oxidation-Reduction; D011487:Protein Conformation; D012247:Rhodospirillum rubrum / Q000201:enzymology*; D012997:Solvents; D013395:Sucrose
chemical_list: D003574:Cytochrome c Group; D005026:Ethylene Glycols; D012997:Solvents; D006418:Heme; D013395:Sucrose; D005990:Glycerol