Analysis of the conformation and stability of rat TTF-1 homeodomain by circular dichroism

Abstract

The conformational stability of TTF-1HD has been determined by CD-monitored thermal denaturation and isothermal urea unfolding studies. The Gibbs free energy of stabilization found are 1.44 and 1.26 kcal·mol⁻¹, respectively. TTF-1HD exhibits a T_m of 42°C and a δC_p of 80 cal·mol⁻¹·K⁻¹ indicating that TTF-1HD, when free in solution, is a mobile flexible segment folded into loose helices. Such a flexibility would be relevant for the DNA-binding function of this homeodomain. In fact, a small reduction of the α-helical content of TTF-1HD significally modifies its DNA-binding activity.