Exploring the mechanism of olfactory recognition in the initial stage by modeling the emission spectrum of electron transfer

• Published in: PloS one Vol. 15; no. 1; p. e0217665
• Main Authors: Liu, Shu, Fu, Rao, Li, Guangwu
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 01.01.2020; Public Library of Science (PLoS)
• Subjects: Acetophenone; Benzaldehyde; Benzaldehydes - pharmacology; Biology and Life Sciences; Bitter taste; Cell Respiration - genetics; Computer simulation; Convolution; Cyanide; Deuteration; Electron states; Electron transfer; Electron Transport - genetics; Electrons; Emission analysis; Emission spectra; Emissions; Energy; Engineering and Technology; Geometry; Humans; Hydrogen; Hydrogen cyanide; Hydrogen Cyanide - pharmacology; Isotopes - pharmacology; Nitrobenzene; Nitrobenzenes - pharmacology; Odorant receptors; Odorants; Odorants - analysis; Odors; Olfaction; Olfactory Perception - genetics; Olfactory Perception - physiology; Olfactory Receptor Neurons - chemistry; Olfactory Receptor Neurons - metabolism; Physical Sciences; Receptors; Receptors, Odorant - genetics; Receptors, Odorant - metabolism; Smell - genetics; Smell - physiology; Social Sciences; Spectra; Vibration; Vibrations; China
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0217665

Olfactory sense remains elusive regarding the primary reception mechanism. Some studies suggest that olfaction is a spectral sense, the olfactory event is triggered by electron transfer (ET) across the odorants at the active sites of odorant receptors (ORs). Herein we present a Donor-Bridge-Acceptor model, proposing that the ET process can be viewed as an electron hopping from the donor molecule to the odorant molecule (Bridge), then hopping off to the acceptor molecule, making the electronic state of the odorant molecule change along with vibrations (vibronic transition). The odorant specific parameter, Huang-Rhys factor can be derived from ab initio calculations, which make the simulation of ET spectra achievable. In this study, we revealed that the emission spectra (after Gaussian convolution) can be acted as odor characteristic spectra. Using the emission spectrum of ET, we were able to reasonably interpret the similar bitter-almond odors among hydrogen cyanide, benzaldehyde and nitrobenzene. In terms of isotope effects, we succeeded in explaining why subjects can easily distinguish cyclopentadecanone from its fully deuterated analogue cyclopentadecanone-d28 but not distinguishing acetophenone from acetophenone-d8.