Structure and stability of a rat odorant-binding protein: another brick in the wall

The effect of temperature on the structure of the rat odorant-binding protein was investigated by spectroscopic and in silico methodologies. In particular, in this work, we examined the structural features of the rat OBP-1F by Fourier-transform infrared spectroscopy and molecular dynamics investigations. The obtained spectroscopic results were analyzed using the following three different methods based on the unexchanged amide hydrogens of the protein sample: (1) the analysis of difference spectra; (2) the generalized 2D-IR correlation spectroscopy; (3) the phase diagram method. The three methods indicated that at high temperatures the rOBP-1F structure undergoes a relaxation process involving the protein tertiary organization before undergoing the denaturation and aggregation processes, suggesting the presence of an intermediate state such as a molten globule-like state. Importantly, the proposed analyses represent a general approach that could be applied to the study of protein stability.