Shape changes in aroma-producing molecules determine the fragrances we detect

December 22, 2008

Shakespeare wrote "a rose by any other name would smell as sweet." But would it if the molecules that generate its fragrance were to change their shape?

That's what Dr. Kevin Ryan, Assistant Professor of Chemistry at The City College of New York (CCNY) and collaborators in the laboratory of Dr. Stuart Firestein, Professor of Biology at Columbia University, set out to investigate. Their findings, reported today in the journal "Chemistry & Biology," shed new insight into how our sense of smell works and have potential applications in the design of flavors and fragrances.

When odor-producing molecules, known as odorants, pass through the nose, they trigger intracellular changes in a subset of the approximately 400 different varieties olfactory sensory neurons (OSN) housed in the nose's internal membrane tissue, Professor Ryan explained. The unique reaction pattern produced, known as the olfactory code, is sent as a signal to the brain, which leads to perception of odors.

Professor Ryan and his team wanted to learn how these receptor cells respond when odorants change their shape. They studied the odorant octanal, an eight-carbon aldehyde that occurs in many flowers and citrus fruits. Octanal is a structurally flexible molecule that can adapt to many different shapes by rotating its chemical bonds.

The researchers designed and synthesized eight-carbon aldehydes that resembled octanal, but had their carbon chains locked by adding one additional bond. These molecules were tested on genetically engineered OSNs known to respond to octanal. This work was done in Professor Firestein's laboratory at Columbia.

The aldehyde molecules that could stretch to their greatest length triggered strong activity in the OSNs. However, those molecules whose carbon chains were constrained into a U shape blocked the receptor and left the cell unable to sense octanal.

"Conformationally constrained odorants were more selective in the number of OSNs they activated," Professor Ryan noted. "The results indicate that these odorant molecules might be able to alter fragrance mixture odors in two ways: by muting the activity of flexible odorants present in a mixture and by activating a smaller subset of OSNs than chemically related flexible odorants. This would produce a different olfactory code signature."

Olfactory receptors belong to the G-protein coupled receptor (GPCR) class of proteins, a family of molecules found in cell membranes throughout the body. Professor Ryan pointed out that half of all commercial pharmaceuticals work by interaction with proteins within this family. Thus, the findings could also have applications to GPCR drug design, as well.

Source: City College of New York

Explore further: High-octane bacteria could ease pain at the pump: Engineered E. coli mass-produce key precursor to potent biofuel

Related Stories

Greenhouse gas chemistry

November 30, 2010

If fossil fuels burn completely, the end products are carbon dioxide and water. Today the carbon dioxide is a waste product, one that goes into the air -- adding to global warming; or the oceans -- acidifying them; or underground ...

In plants, small changes make big impact

October 7, 2010

( -- You can’t see them or feel them, but right now countless biochemical interactions in your body affect your life in countless ways. These interactions are important because if they go poorly, really bad ...

Recommended for you

NASA's space-station resupply missions to relaunch

November 29, 2015

NASA's commercial space program returns to flight this week as one of its private cargo haulers, Orbital ATK, is to launch its first supply shipment to the International Space Station in more than 13 months.

CERN collides heavy nuclei at new record high energy

November 25, 2015

The world's most powerful accelerator, the 27 km long Large Hadron Collider (LHC) operating at CERN in Geneva established collisions between lead nuclei, this morning, at the highest energies ever. The LHC has been colliding ...


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.