Vibrationally assisted olfaction

Olfaction is the sense of smell. This sense is mediated by specialized sensory cells of the nasal cavity of vertebrates. Many vertebrates, including most mammals and reptiles, have two distinct olfactory systems—the primary olfactory system and the accessory olfactory system (used mainly to detect pheromones). For air-breathing animals, the primary olfactory system detects volatile chemicals, and the accessory olfactory system detects fluid-phase chemicals. Olfaction, along with taste, is a form of chemoreception. The chemicals themselves that activate the olfactory system, in general at deficient concentrations, are called odorants.

The mainstream theory of olfaction is based on the so-called lock-and-key model. According to this theory, the size, shape and functional groups of odorant compounds determine the activation of olfactory receptors. Once an associated odorant molecule binds to an olfactory receptor, the receptor is activated and triggers a neural signal. Olfactory receptors have been identified as G-protein coupled receptors (GPCRs) [Buck and Axel, Cell (Cambridge, Mass.) 65, 175 (1991)]. Since most of the GPCRs, e.g., β-adrenergic agonists, are activated through the binding of ligands and are highly sensitive to ligands' conformation and surface properties, the lock-and-key mechanism seems to be a natural explanation of olfaction.

An alternative mechanism of olfaction has been suggested. According to this mechanism, the differences in key vibrational frequencies of odorant compounds contribute to odor perception [Turin, Chem. Senses 21, 773 (1996)]. A plausible way of sensing the vibrational spectrum of an odorant is furnished through electron transfer in the olfactory receptor. In this project, we are interested in understanding whether molecular vibrations could assist electron transfer in olfactory receptors.

Recent Publications

How Far Does a Receptor Influence Vibrational Properties of an Odorant?, Anna Reese, Nanna Holmgaard List, Jacob Kongsted, Ilia A. Solov'yov, PLoS ONE, 11, 10.1371/journal.pone.0152345, (2016)
Vibrationally Assisted Electron Transfer Mechanism of Olfaction: Myth or Reality?, Ilia A. Solov'yov, Po-Yao Chang, Klaus Schulten, Phys. Chem. Chem. Phys., 14, 13861-13871, (2012)