Question

In a study of the temperature-induced reversible denaturation of chymotrypsinogen, the slope of your van't Hoff plot is -533 kJ/mol. This means that the:

	equilibrium constant for denaturation is 533
		free energy change, ΔG, of denaturation is -533 kJ/mol
		enthalpy change, ΔH, of denaturation is +533 kJ/mol
		enthalpy change, ΔH, of denaturation is -533 kJ/mo

Answer 1

Consider the equilibrium

Native protein Denatured protein

Keq = [Denatured]/[Native]

First we will derive the van't Hoff equation

G = H - TS

Also for a reaction of folding and unfolding G = -RTlnKeq

Equating the above two equations, we get

H - TS = -RTlnKeq

Keq = -H/RT + S /R (This is van't Hoff equation)

This equation is plotted

For van't Hoff plot, slope = -H/R

Given slope = -533 KJ/mol = -H/R

Hence, enthalpy change, ΔH, of denaturation is +533 kJ/mol