Influence of glycerol on the structure and redox properties of horse heart cytochrome c. A circular dichroism and electrochemical study.
The effect of glycerol on the structure and redox properties of horse heart cytochrome c was investigated by absorption spectroscopy, circular dichroism, and dc cyclic voltammetry techniques. The results show that the organic solvent increases the alpha-helix structure of the protein and induces slight changes at the active-site environment: however, the overall tertiary structure does not appear to be significantly perturbed. Glycerol stabilizes cytochrome c, the free energy of denaturation (delta G0) being approximately 0.7 kcal/mol larger than that determined in phosphate buffer under the same conditions, and influences the heterogeneous electron transfer kinetics at a chemically modified gold electrode: on the other hand, the redox potential of the protein is unaltered. On the whole, the results obtained indicate that glycerol acts as a suitable stabilizing agent of cytochrome c, which is of interest for application in biotechnology: the organic solvent does not alter the tertiary structure significantly or the redox properties of the protein. This has to be interpreted not only in terms of the glycerol-induced solvent ordering around the protein surface, but also as due to the specific features of the protein matrix.
De Sanctis
G
G
Department of Biology M.C.A., University of Camerino, Italy.
Maranesi
A
A
Ferri
T
T
Poscia
A
A
Ascoli
F
F
Santucci
R
R
D000818:Animals; D001665:Binding Sites; D002942:Circular Dichroism; D003574:Cytochrome c Group / Q000737:chemistry* / Q000378:metabolism*; D004563:Electrochemistry; D004579:Electron Transport / Q000187:drug effects; D005990:Glycerol / Q000494:pharmacology*; D019791:Guanidine; D006146:Guanidines / Q000494:pharmacology; D006420:Hemeproteins / Q000378:metabolism; D006736:Horses; D009206:Myocardium / Q000737:chemistry* / Q000378:metabolism; D010084:Oxidation-Reduction; D011489:Protein Denaturation; D017510:Protein Folding; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D013053:Spectrophotometry; D013816:Thermodynamics
D003574:Cytochrome c Group; D006146:Guanidines; D006420:Hemeproteins; D019791:Guanidine; D005990:Glycerol