Computational evidence for vibrational effects in olfaction has also been mixed. A three-state model for inelastic electron transfer in fruit flies suggested that vibrational effects play a role in the detection of acetophenone, but these effects were not expected to generalize to other odorant molecules . A more detailed quantum chemical model predicted differential binding of deuterated octanoic acid, but not acetone, compared to its hydrogenated form ; the latter study also observed that a trained dog could partially distinguish between D 15and H 15 -octanoic acid. The experimental structure and associated molecular dynamics simulation of OR51E2 obtained in presents an opportunity to advance by simulation the understanding of vibrational isotope effects on this critical first step in olfaction.