Denaturation and Renaturation of Self-Assembled Yeast Iso-1-cytochrome c on Au

• Published in: Analytical chemistry (Washington) 2004-04, Vol.76 (7), p.2112-2117
• Main Authors: Chah, Soonwoo, Kumar, Challa V, Hammond, Matthew R, Zare, Richard N
• Format: Article
• Language: English
• Subjects: Analytical biochemistry: general aspects, technics, instrumentation; Analytical, structural and metabolic biochemistry; Biological and medical sciences; Cytochromes c - chemistry; Fundamental and applied biological sciences. Psychology; Gold - chemistry; Protein Denaturation; Protein Renaturation; Protein Structure, Tertiary; Saccharomyces cerevisiae Proteins - chemistry; Structure-Activity Relationship; Surface Plasmon Resonance - methods; Thermodynamics; Urea - pharmacology
• ISSN: 0003-2700; 1520-6882
• DOI: 10.1021/ac035416k

We have made surface plasmon resonance (SPR) measurements of yeast iso-1-cytochrome c (Cyt c) on a gold surface. Angle-resolved SPR curves are recorded as a function of urea concentration before and after self-assembly of the Cyt c. Exposure to a urea solution causes denaturation of Cyt c, which shifts the minimum in the SPR curve to a larger angle and decreases the signal amplitude. The Gibbs free energy change for denaturation of the protein on Au is calculated from the change of the SPR signal amplitude with urea concentration. We find that (1) Cyt c can be reversibly denatured and renatured, depending on the urea concentration, and (2) the Gibbs free energy change for denaturation of Cyt c on Au surface in water, ΔG°water, is 1.5 kcal/mol, which is ∼4 times less than that in bulk solution.