Information about Vibration Theory
The Vibration theory (or more precisely, hypothesis) of smell is that the quality of a particular odour arises from olfactory receptors' responding to frequencies of vibrations of odour molecules in the infrared range. The theory is opposed to the more widely accepted shape theory of olfaction in which the shape of odorant molecules allow them to fit into membrane proteins in the olfactory receptors.
In vibration theory, the vibration frequency of odour molecules is transduced via inelastic electron tunneling of a charge from one part of the receptor to a different energy level in another part of the receptor protein. For strong tunnelling to be possible, it is necessary not only for the shape of the odorant molecule to be compatible with the shape of the receptor, but also for the odorant molecule to have a vibrational energy mode compatible with the difference in energies between the two energy levels on the receptor. The quality of a particular odour is encoded in the ratio of activities of receptors tuned to different vibration frequencies, in the same way that colour is encoded in the ratio of activities of cone cell receptors tuned to different frequencies of light.
Some evidence supports vibration theory; some evidence supports shape theory. Although vibration theory explains the quality of odours, it does not explain intensity of odours, why some odours are stronger than others at the same concentrations.
An experiment reported in a book regarding Luca Turin's research consisted of mixing the mint isomer with butanone, on the theory that the shape of the G-protein-coupled receptor prevented the carbonyl group in the mint isomer from being detected by the "biological spectroscope". The experiment succeeded: a mixture of 60% butanone and 40% mint carvone smells like caraway, a success for the vibration theory of olfaction.
In vibration theory, the vibration frequency of odour molecules is transduced via inelastic electron tunneling of a charge from one part of the receptor to a different energy level in another part of the receptor protein. For strong tunnelling to be possible, it is necessary not only for the shape of the odorant molecule to be compatible with the shape of the receptor, but also for the odorant molecule to have a vibrational energy mode compatible with the difference in energies between the two energy levels on the receptor. The quality of a particular odour is encoded in the ratio of activities of receptors tuned to different vibration frequencies, in the same way that colour is encoded in the ratio of activities of cone cell receptors tuned to different frequencies of light.
Some evidence supports vibration theory; some evidence supports shape theory. Although vibration theory explains the quality of odours, it does not explain intensity of odours, why some odours are stronger than others at the same concentrations.
Support
Explaining differences in stereoisomer scents
Carvone presented a perplexing situation to vibration theory. Carvone has two isomers, both of which vibrate the same yet smell different. One smells like mint and the other like caraway (for which it is named).An experiment reported in a book regarding Luca Turin's research consisted of mixing the mint isomer with butanone, on the theory that the shape of the G-protein-coupled receptor prevented the carbonyl group in the mint isomer from being detected by the "biological spectroscope". The experiment succeeded: a mixture of 60% butanone and 40% mint carvone smells like caraway, a success for the vibration theory of olfaction.
Challenging shape theory
- Similarly shaped molecules with different molecular vibrations have different smells (metallocene experiment and deuterium replacement of molecular hydrogen)
- Differently shaped molecules with similar molecular vibrations have similar smells (replacement of carbon double bonds by sulphur atoms and the disparate shaped amber odorants)
- Hiding functional groups does not hide the group's characteristic odor
Challenges
Three predictions by Luca Turin on the nature of smell, using concepts of vibration theory, have been claimed to be false (Keller and Vosshall, 2004).References
- Turin, Luca, (1996). A spectroscopic mechanism for primary olfactory reception. Chemical Senses. 21(6):773-791
- Burr, Chandler (2003). The Emperor of Scent: A Story of Perfume, Obsession, and the Last Mystery of the Senses. New York: Random House. ISBN 0-375-50797-3.
- Keller, A and Vosshall, LB. (2004). A psychophysical test of the vibration theory of olfaction. Nature Neuroscience 7:337-338. See also the editorial on p. 315. (Newsletter report, Rockefeller University Scientist).
A hypothesis (from Greek ὑπόθεσις) consists either of a suggested explanation for a phenomenon or of a reasoned proposal suggesting a possible correlation between multiple phenomena.
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Olfaction (also known as olfactics) refers to the sense of smell. This sense is mediated by specialized sensory cells of the nasal cavity of vertbrates, and, by analogy, sensory cells of the antennae of invertebrates.
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Olfactory receptors are class A G protein-coupled receptor which play a role in signal transduction to olfactory receptor neurons.
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Expression
In vertebrates, the olfactory receptors are located in the cilia of the olfactory sensory neurons...... Click the link for more information.
A molecular vibration occurs when atoms in a molecule are in periodic motion while the molecule as a whole has constant translational and rotational motion. The frequency of the periodic motion is known as a vibration frequency.
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The Shape theory of smell states that the sensation of smell is due to a 'lock and key' mechanism by which a scent molecule fits into olfactory receptors in the nasal lamina of the nose.
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Support
Dr. John E. Amoore came up with the shape theory in 1952 at Oxford University...... Click the link for more information.
In biology, signal transduction refers to any process by which a cell converts one kind of signal or stimulus into another, most often involving ordered sequences of biochemical reactions inside the cell, that are carried out by enzymes, activated by second messengers resulting in
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In quantum mechanics, quantum tunnelling is a micro and nanoscopic phenomenon in which a particle violates principles of classical mechanics by penetrating or passing through a potential barrier or impedance higher than the kinetic energy of the particle.
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Color or colour[1] (see spelling differences) is the visual perceptual property corresponding in humans to the categories called red, yellow, blue, black, etc.
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Cone cells, or cones, are photoreceptor cells in the retina of the eye which function best in relatively bright light. The cone cells gradually become more sparse towards the periphery of the retina.
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Carvone is a member of a family of chemicals called terpenoids.[1] Carvone is found naturally in many essential oils, but is most abundant in the oils from seeds of caraway (Carum carvi) and dill.
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In chemistry, isomers are molecules with the same chemical formula and often with the same kinds of chemical bonds between atoms, but in which the atoms are arranged differently (analogous to a chemical anagram).
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Mint - online financial services (credit cards, insuance and loans)
Mint is an online financial services brand and part of the Royal Bank of Scotland Groups Retail - Direct Channels Division. The Mint credit card was introduced as a replacement for the RBS Advanta card.
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Mint is an online financial services brand and part of the Royal Bank of Scotland Groups Retail - Direct Channels Division. The Mint credit card was introduced as a replacement for the RBS Advanta card.
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C. carvi
Binomial name
Carum carvi
L.
Caraway or Persian cumin (Carum carvi) is a biennial plant in the family Apiaceae, native to Europe and western Asia.
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Binomial name
Carum carvi
L.
Caraway or Persian cumin (Carum carvi) is a biennial plant in the family Apiaceae, native to Europe and western Asia.
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Luca Turin (1953 - ) is a biophysicist with a long-standing interest in the sense of smell, the art of perfume, and the fragrance industry.
Since 1996 Turin has been the leading proponent of the vibration theory of olfaction, which proposes that the vibrational spectroscopic
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Since 1996 Turin has been the leading proponent of the vibration theory of olfaction, which proposes that the vibrational spectroscopic
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Butanone is a manufactured organic chemical. It is a colorless liquid with a sharp, sweet odor. It is a ketone, also known as methyl ethyl ketone (MEK).
Butanone is produced in large quantities.
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Butanone is produced in large quantities.
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G protein-coupled receptors (GPCRs), also known as seven transmembrane receptors, 7TM receptors, heptahelical receptors, and G protein linked receptors (GPLR
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carbonyl group is a functional group composed of a carbon atom double-bonded to an oxygen atom : C=O.
The term carbonyl can also refer to carbon monoxide as a ligand in an inorganic or organometallic complex (a metal carbonyl, e.g.
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The term carbonyl can also refer to carbon monoxide as a ligand in an inorganic or organometallic complex (a metal carbonyl, e.g.
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A metallocene is a compound with the general formula (C5R5)2M consisting of two cyclopentadienyl anions (Cp) bound to a metal center in the oxidation state II. Closely related to the metallocenes are the metallocene derivatives, e.g.
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Deuterium, also called heavy hydrogen, is a stable isotope of hydrogen with a natural abundance in the oceans of Earth of approximately one atom in 6500 of hydrogen (~154 PPM). Deuterium thus accounts for approximately 0.015% (on a weight basis, 0.
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1, −1
(amphoteric oxide)
Electronegativity 2.20 (Pauling scale) More
Atomic radius 25 pm
Atomic radius (calc.) 53 pm
Covalent radius 37 pm
Van der Waals radius 120 pm
Miscellaneous
Thermal conductivity (300 K) 180.
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(amphoteric oxide)
Electronegativity 2.20 (Pauling scale) More
Atomic radius 25 pm
Atomic radius (calc.) 53 pm
Covalent radius 37 pm
Van der Waals radius 120 pm
Miscellaneous
Thermal conductivity (300 K) 180.
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4, 2
(mildly acidic oxide)
Electronegativity 2.55 (Pauling scale)
Ionization energies
(more) 1st: 1086.5 kJmol−1
2nd: 2352.6 kJmol−1
3rd: 4620.5 kJmol−1
Atomic radius 70 pm
Atomic radius (calc.
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(mildly acidic oxide)
Electronegativity 2.55 (Pauling scale)
Ionization energies
(more) 1st: 1086.5 kJmol−1
2nd: 2352.6 kJmol−1
3rd: 4620.5 kJmol−1
Atomic radius 70 pm
Atomic radius (calc.
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6
(strongly acidic oxide)
Electronegativity 2.58 (Pauling scale)
Ionization energies
(more) 1st: 999.6 kJmol−1
2nd: 2252 kJmol−1
3rd: 3357 kJmol−1
Atomic radius 100 pm
Atomic radius (calc.
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(strongly acidic oxide)
Electronegativity 2.58 (Pauling scale)
Ionization energies
(more) 1st: 999.6 kJmol−1
2nd: 2252 kJmol−1
3rd: 3357 kJmol−1
Atomic radius 100 pm
Atomic radius (calc.
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In organic chemistry, functional groups (or moieties) are specific groups of atoms within molecules, that are responsible for the characteristic chemical reactions of those molecules.
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Herod_Archelaus
