Theoretical Analysis of Androstenone Adsorption on Chimpanzee and Gorilla Olfactory Receptors (G-Protein): Statistical Physics Modeling, Molecular Docking Simulation, and Thermodynamic Investigation.

An advanced theory based on statistical physics was applied to microscopically investigate androstenone adsorption and its relationship with olfactory perception in chimpanzees and gorillas. For this purpose, dose-response curves of androstenone on olfactory receptors of chimpanzee OR7D4 and gorilla OR7D4 were analyzed by statistical physics. The two-energy adsorption model fits the chimpanzee data well, and the gorilla data are best fit by the one-energy adsorption model. The stereographic parameter analysis indicated that the studied pheromones were docked in a nonparallel manner in both species via a multimolecular mechanism. The analysis showed that the molecules interacted with different amino acid residues, resulting in distinct olfactory responses. The positive values of the molar adsorption energies indicate that an exothermic and physisorption process occurred in both olfactory systems. The docking analysis revealed that androstenone binds to the olfactory receptors of chimpanzees and gorillas through specific interactions with amino acid residues in the binding pockets. The docking results indicated distinct binding modes in each species, involving van der Waals, alkyl, and C-H interactions, which corroborated the energy trends predicted by the statistical physics model. These findings provided insights into the molecular mechanisms underlying the differential olfactory responses in chimpanzees and gorillas. Statistical physics was an excellent tool for evaluating and interpreting the interactions between androstenone and olfactory receptors.