Our nose’s ability to distinguish hundreds of odors has been assumed to be largely based on the different shapes of odorant molecules, disposing different binding characteristics towards olfactory receptor proteins. However, in recent studies, humans and animals perceived different smells between deuterated and non-deuterated odorants, although these retain their initial shape and surface characteristics.

Klaus Schulten and colleagues, University of Illinois, Champaign, USA, are among the first researchers to consider the energetics of the olfaction process in detail. From the knowledge of biological binding properties and ab initio calculations of odorant molecules, they concluded that the vibrational energy of vibrationally excited odorants can promote an electron transfer in the receptor. The calculations demonstrate that electron transfer and vibrations might be coupled in the olfactory process, in the same way as in electron transfer in Marcus theory.

This discovery might finally elucidate the yet incompletely understood human olfactory sense.

• Vibrationally assisted electron transfer of olfaction: myth or reality?,
  I. A. Solovgov, P.-Y. Chang, K. Schulte,
  Phys. Chem. Chem. Phys. 2012.
  DOI: 10.1039/C2CP41436H