|The Rosy Periwinkle |
Whilst I was homogenising the lemons, I was immediately transported to my
organic chemistry classes as an undergraduate at Sheffield and I remembered the story of oranges and lemons and the chirality of limonene. The characteristic difference between the smell of oranges and lemons couldn't be more subtle, from a chemical perspective. As you can see left the two molecules differ only with respect to their chirality. That is, both molecules are mirror images, like left and right hands. But that's clearly enough to change the way our brain interprets their smell, or odour. Which brings me nicely on to "quantum biology".
It has been suggested that the translation of the information from a small molecule such as limonene into a sensory perception is partly a result of the shape of the molecule, but is possibly a result of the molecule's quantum level vibrational fingerprint! So as you know, all bonds have a characteristic set of vibration frequencies derived from bending, stretching etc. You may have come across this in Chemistry. These phenomena can be understood using quantum theory and unlike the lock and key concept (which we will explore soon) it has been suggested that neuronal responses to odour are triggered by quantum vibrations. So why would a good experiment be to compare the sell of limonene in both chiral forms with a deuterated version?