A protein completely unfolds in 8 M Urea. The stability of the folded state in water is calculated to be 8 kCal/mole at 25°C. What is the likely ΔG…
A protein completely unfolds in 8 M Urea. The stability of the folded state in water is calculated to be 8 kCal/mole at 25°C. What is the likely ΔG of the following reaction in 8 M Urea?A(native) → A(unfolded) Choose the correct answer :
Select an option to attempt
Correct Answer: Option B
Explanation
Thermodynamics of protein unfolding in 8M urea:Given:• Stability of folded state in water:(positive = folded state is more stable, unfolding is unfavourable in water)Reaction of interest:in 8M urea.• In 8M urea, the protein COMPLETELY unfolds — meaning this reaction proceeds spontaneously.• For a spontaneous reaction:Therefore,for unfolding in 8M urea is LESS THAN ZERO (negative).Note: The magnitude is not exactly −8 kcal/mol because urea changes the free energy landscape (it stabilises the unfolded state by disrupting hydrophobic interactions and H-bonds).Answer: Less than zero (Option 2).