Tracking ligand-binding effect on protein stability by CD spectroscopy

The influence of protein-ligand interactions on protein stability is usually assessed by measurements in the liquid phase. CD spectroscopy appears to be a tool of choice to i) measure the conformation of the protein in different phases and to ii) follow the conformational changes of the protein upon binding.We therefore studied the stability of the rat odorant binding protein 3 (OBP3), its ability to remain functional and a preliminary test of its ligand binding specificity in the dry state. Solid-state spectra were performed on dry thin films prepared by drop casting of initial buffered aqueous solutions of the rat OBP3 onto optically transparent CaF2 windows and subsequently dried under l…