Effect of ionic strength on the interfacial properties of cytochrome c

• Published in: Biochimica et biophysica acta Vol. 1432; no. 1; pp. 82 - 91
• Main Authors: Gažová, Zuzana, Antalı́k, Marián, Bágel’ová, Jaroslava, Tomori, Zoltán
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 15.06.1999
• Subjects: Cytochrome c Group - chemistry; Ferricytochrome c; Hydrogen-Ion Concentration; Molten globule state; Osmolar Concentration; Oxidation-Reduction; Pendant drop method; Protein Conformation; Solutions; Surface Tension; Unfolding; Ferricytochrome c; Unfolding; Pendant drop method; Molten globule state; Surface tension
• ISSN: 0167-4838; 0006-3002; 1879-2588
• DOI: 10.1016/S0167-4838(99)00091-6

The surface tension behaviour of oxidised cytochrome c (cyt c) solution was characterised at various pH and ionic strength at the air/water interface. The pendant drop method employing digital image analysis of the drop shape was applied to the measurement of the surface tension. The adsorption properties of cyt c were utilised to study the protein conformation change effected by acidification and ionic strength. At high ionic strength, the saturated steady-state surface tension shows a cooperative change centred around 3.6 induced by a decrease in pH. Using spectroscopic experiments, the apparent p K of the acid-induced transition of horse cyt c from the native to the molten globular state is equal to 3.5. This fact indicates that the saturated steady-state surface tension is a parameter which might be used to monitor conformation changes of cyt c.