Quantitative characterizations of mOR-EG activated by vanilla odorants using advanced statistical physics modeling.

An advanced monolayer adsorption model of an ideal gas was successfully employed to investigate the adsorption of vanillin, vanillin methyl ether, vanillin ethyl ether, and vanillin acetate odorants on mouse eugenol olfactory receptor mOR-EG. In order to understand the adsorption process putatively introduced in olfactory perception, model parameters were analyzed. Hence, fitting results showed that the studied vanilla odorants were linked in mOR-EG binding pockets with a non-parallel orientation, and their adsorption was a multi-molecular process (n > 1). The adsorption energy values that ranged from 14.021 to 19.193 kJ/mol suggested that the four vanilla odorants were physisorbed on mOR-EG (ΔE < 40 kJ/mol) and the adsorption mechanism may be considered as an exothermic mechanism (ΔE > 0). The estimated parameters may also be utilized for the quantitative characterization of the interactions of the studied odorants with mOR-EG to determine the corresponding olfactory bands ranging from 8 to 24.5 kJ/mol.