Theoretical assessment of the adsorption mechanism of carvone enantiomers on cow btOR1A1: New microscopic interpretations

In this study, the olfactory threshold concentration was introduced in the statistical physics approach to provide fruitful and deep discussions. Indeed, a modified mono-layer mono-energy model established using statistical physics theory was successfully used to theoretically study the adsorption involved in the olfactory response of (R)-(−)-carvone and (S)-(+)-carvone key food odorants (KFOs) on cow (Bos taurus) olfactory receptor btOR1A1 through the analysis of the different model physicochemical parameters. Thus, stereographic results indicated that the two carvone enantiomers were non-parallelly docked on btOR1A1 binding sites during the adsorption process since the different values of n were superior to 1. Molecular docking studies suggest that the high olfactory response of (R)-(−)-carvone was attributed to the specific types of interactions observed. The energetic results showed via the fitted values of the molar adsorption energies, which were positive and lower than 5 kJ/mol, that the studied enantiomers were exothermically physisorbed via conventional hydrogen bond, pi-alkyl, alkyl, pi-sigma, and van der Waals interactions for (R)-(−)-carvone-btOR1A1 complex and via carbon hydrogen bond, alkyl, pi-alkyl, pi-sigma, and van der Waals interactions for (S)-(+)-carvone-btOR1A1 complex. Moreover, the cow olfactory responses were detected only when 0.49 % and 8.63 % of btOR1A1 binding sites are fired or occupied by (R)-(−)-carvone and (S)-(+)-carvone, respectively. These parameters may also be employed to quantitatively characterize the two olfactory systems.