Navigation Links
Odorant shape and vibration likely lead to olfaction satisfaction
Date:9/19/2012

CHAMPAIGN, Ill. A new study of the sense of smell lends support to a controversial theory of olfaction: Our noses can distinguish both the shape and the vibrational characteristics of odorant molecules.

The study, in the journal Physical Chemistry Chemical Physics, demonstrates the feasibility of the theory first proposed decades ago that the vibration of an odorant molecule's chemical bonds the wagging, stretching and rocking of the links between atoms contributes to our ability to distinguish one smelly thing from another.

"The theory goes that when the right odorant binds to its receptor, the odorant's molecular vibration allows electrons to transfer from one part of the receptor to another," said University of Illinois physics and Beckman Institute professor Klaus Schulten, who conducted the analysis with postdoctoral researcher Ilia Solov'yov and graduate student Po-Yao Chang. "This electron transfer appears to fine-tune the signal the receptor receives."

(Watch a video about the research.)

Many who study olfaction maintain that odorant receptors recognize only an odorant's shape and surface characteristics. They dismiss the idea that molecular vibration has anything to do with it, Schulten said. Likewise, some proponents of the vibrational theory think that molecular vibration only, and not shape, guides the sense of smell. Schulten and his colleagues belong to a "third camp" that sees evidence for both, he said.

The vibrational theory of olfaction is supported by studies showing that insects, humans and other animals can tell the difference between two versions of the same odorant molecule a normal one and an identical one with deuterium atoms substituted for each of the hydrogens. The deuterated and normal versions of the odorant have the same shape and surface characteristics, and yet humans and other animals can smell the difference, Schulten said.

"The question then is of course, for scientists, how does this happen?" he said.

To answer this question, Schulten turned to the work of a former colleague at Illinois, Rudolph Marcus, a chemist (now at Caltech) who received the Nobel Prize in Chemistry in 1992 for his insights into electron transfer, one of the most basic forms of a chemical reaction.

"Marcus realized that when electrons are being exchanged between molecules the process is coupled to the vibrations of the molecules involved," Schulten said. Marcus focused primarily on the low-frequency "rumblings" that occur as a result of molecular vibration in large molecules, Schulten said.

Odorant molecules are generally quite small, however, with a lot of high-frequency, high-energy vibrations, Schulten said. Some scientists have theorized that these high-frequency vibrations can, when an odorant binds to the right receptor, enhance the likelihood that an electron will transfer from one part of the receptor to another, sending an electrical signal that contributes to the detection of that odor.

Prior to the new study, no one had analyzed the energetics of the system to see if the vibrations of the odorant molecules in the context of all the background vibrations that are part of the system could actually promote electron transfer within the receptor. Schulten and his colleagues are the first to conduct such an analysis, he said.

"You can actually carry out quantum chemical calculations that determine very precisely the vibration of the molecule as well as the ability to couple it to electron transfer," Schulten said. The calculations indicate that such an interaction is energetically feasible, he said.

Odorant receptors are embedded in membranes and so are more difficult to study than other proteins. But previous research indicates that some receptors are metalloproteins, and "the metals in the proteins are pre-designed to transfer electrons," Schulten said. "We also see that there are other amino acid side groups that can accept an electron, so the electron can be transferred through the protein."

Like others before them, Schulten and his colleagues suggest that the odorant receptor contains both an electron donor and an electron acceptor, but that electron transfer occurs only when a specific odorant is bound to the receptor. The new calculations offer the first quantitative evidence that the odorant can in fact promote electron transfer.

Those who suggested that molecular vibration played a role in odorant recognition in previous studies "didn't know about Marcus' theory and they didn't do quantum chemical calculations," Schulten said. "They argued very much on principle (that it was possible). So we are saying now, yes, it is really possible even when you do the most complete and reliable calculations."


'/>"/>

Contact: Diana Yates
217-333-5802
University of Illinois at Urbana-Champaign
Source:Eurekalert  

Related biology news :

1. Oh, my stars and hexagons! DNA code shapes gold nanoparticles
2. Cells to Civilizations: The Principles of Change That Shape Life
3. Simple mathematcal pattern describes shape of neuron jungle
4. Not a 1-way street: Evolution shapes environment of Connecticut lakes
5. International team uncovers new genes that shape brain size, intelligence
6. Did climate change shape human evolution?
7. The shape of things to come: NIST probes the promise of nanomanufacturing using DNA origami
8. African Americans less likely to adhere to DASH diet for lowering blood pressure
9. Coral scientists use new model to find where corals are most likely to survive climate change
10. Southern elephant seals likely detect prey bioluminescence for foraging
11. Research warns Asia unlikely to achieve climate, poverty goals unless womens rights are recognized
Post Your Comments:
*Name:
*Comment:
*Email:
Related Image:
Odorant shape and vibration likely lead to olfaction satisfaction
(Date:6/22/2016)... , June 22, 2016  The American College of Medical ... Show Executive Magazine as one of the fastest-growing trade ... 25-27 at the Bellagio in Las Vegas ... highest percentage of growth in each of the following categories: ... companies and number of attendees. The 2015 ACMG Annual Meeting ...
(Date:6/21/2016)... 21, 2016 NuData Security announced today that ... of principal product architect and that Jon ... customer development. Both will report directly to ... moves reflect NuData,s strategic growth in its product ... customer demand and customer focus values. ...
(Date:6/15/2016)... York , June 15, 2016 ... new market report titled "Gesture Recognition Market by Application ... Forecast, 2016 - 2024". According to the report, the  ... 11.60 billion in 2015 and is estimated to ... USD 48.56 billion by 2024.  Increasing ...
Breaking Biology News(10 mins):
(Date:6/23/2016)... -- A person commits a crime, and the detective uses ... criminal down. An outbreak of foodborne illness makes ... uses DNA evidence to track down the bacteria that caused ... not. The FDA has increasingly used a complex, cutting-edge technology ... Put as simply as possible, whole genome sequencing is a ...
(Date:6/23/2016)... SAN FRANCISCO , June 23, 2016   ... it has secured $1 million in debt financing from ... to ramp up automation and to advance its drug ... for its new facility. "SVB has been ... goes beyond the services a traditional bank would provide," ...
(Date:6/23/2016)... NEWPORT BEACH, Calif. , June 23, 2016 /PRNewswire/ ... offering new biological discoveries to the medical community, has ... and co-founder Matthew Nunez . "We ... provide us with the capital we need to meet ... funding will essentially provide us the runway to complete ...
(Date:6/23/2016)... ... 2016 , ... Velocity Products, a division of Morris Group, ... exclusively for Okuma CNC machining centers at The International Manufacturing Technology Show, IMTS, ... companies with expertise in toolholding, cutting tools, machining dynamics and distribution, Velocity SMART ...
Breaking Biology Technology: