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Luca Turin (born 20 November 1953) is a biophysicist and writer with a long-standing interest in the sense of smell, perfumery, and the fragrance industry. ==Vibration theory of olfaction== A major prediction of Turin's vibration theory of olfaction is the isotope effect: that the normal and deuterated versions of a compound should smell different due to unique vibration frequencies, despite having the same shape. A 2001 study by Haffenden et al. showed humans able to distinguish benzaldehyde from its deuterated version.〔 see also ()〕 However, experimental tests published in Nature Neuroscience in 2004 by Keller and Vosshall failed to support this prediction, with human subjects unable to distinguish acetophenone and its deuterated counterpart. The study was accompanied by an editorial, which considered the work of Keller and Vosshall to be "refutation of a theory that, while provocative, has almost no credence in scientific circles." It continued, "The only reason for the authors to do the study, or for ''Nature Neuroscience'' to publish it, is the extraordinary -- and inappropriate -- degree of publicity that the theory has received from uncritical journalists." The journal also published a review of ''The Emperor of Scent'', calling Chandler Burr's book about Turin and his theory "giddy and overwrought." Proponents note that the potential presence of a vested interest on the part of large brands and retailers in complex and mystical attitudes towards the production of fragrance substances leaves suspect the dispute over Turin's scientific theory as a means of avoiding a rapid shift in the consumer market which would threaten brand stability and profits. In addition, tests with animals have shown fish and insects able to distinguish isotopes by smell. Biophysical simulations published in Physical Review Letters in 2007 suggest that Turin's proposal is viable from a physics standpoint. The vibration theory received possible support from a 2004 paper published in the journal Organic Biomolecular Chemistry by Takane and Mitchell, which shows that odor descriptions in the olfaction literature correlate more strongly with vibrational frequency than with molecular shape. In 2011, Turin and colleagues published a paper in PNAS showing drosophila fruit flies can distinguish between odorants and their deuterated counterparts. Tests on drosophila differ from human experiments by using an animal subject known to have a good sense of smell and free from psychological biases that may complicate human tests.〔 (【引用サイトリンク】 url = http://www.nature.com/news/2011/110214/full/news.2011.39.html ) 〕 Drosophila were trained to avoid the deuterated odorant in a deuterated/normal pair, indicating a difference in odor. Furthermore, drosophila trained to avoid one deuterated odorant also avoided other deuterated odorants, chemically unrelated, indicating that the deuterated bond itself had a distinct smell. The authors identified a vibrational frequency that could be responsible and found it close to one found in nitriles. When flies trained to avoid deuterated odorants were exposed to the nitrile and its non-nitrile counterpart, the flies also avoided the nitrile, consistent with the theory that fly olfaction detects molecular vibrations. 〔 (【引用サイトリンク】 url = http://www.pnas.org/content/early/2011/02/08/1012293108.abstract ) 〕 Two years later, in 2013, Turin and colleagues published a study in PLoS ONE showing that humans easily distinguish gas-chromatography-purified deuterated musk in double-blind tests. The team chose musks due to the high number of carbon-hydrogen bonds available for deuteration. They replicated the earlier results of Vosshall and Keller showing that humans cannot reliably distinguish between acetophenone and its deuterated counterpart, with 8 hydrogens, and showed that humans only begin to detect the isotope odor of the musks beginning at 14 deuteriums, or 50% deuteration.〔Gane S, Georganakis D, Maniati K, Vamvakias M, Ragoussis N, Skoulakis EMC, Turin L (2013). "Molecular vibration-sensing component in human olfaction." ''PLoS ONE'' 8, e55780. 〕 Because Turin's proposed mechanism is a biological method of inelastic electron tunnelling spectroscopy, which exploits a quantum effect, his theory of olfaction mechanism has been described as an example of quantum biology. In response to Turin's 2013 paper, involving deuterated and undeuterated isotopomers of the musk cyclopentadecanone,〔 Block et al. in a 2015 paper in PNAS report that the human musk-recognizing receptor, OR5AN1, identified using a heterologous olfactory receptor expression system and robustly responding to cyclopentadecanone and muscone (which has 30 hydrogens), fails to distinguish isotopomers of these compounds in vitro. Furthermore, the mouse (methylthio)methanethiol-recognizing receptor, MOR244-3, as well as other selected human and mouse olfactory receptors, responded similarly to normal, deuterated, and carbon-13 isotopomers of their respective ligands, paralleling results found with the musk receptor OR5AN1. Based on these findings, the authors conclude that the proposed vibration theory of olfaction does not apply to the human musk receptor OR5AN1, mouse thiol receptor MOR244-3, or other olfactory receptors examined. Additionally, theoretical analysis by the authors shows that the proposed electron transfer mechanism of the vibrational frequencies of odorants could be easily suppressed by quantum effects of nonodorant molecular vibrational modes. The authors conclude: “These and other concerns about electron transfer at olfactory receptors, together with our extensive experimental data, argue against the plausibility of the vibration theory.” In commenting on this work, Vosshall writes “In PNAS, Block et al…. shift the “shape vs. vibration” debate from olfactory psychophysics to the biophysics of the ORs themselves. The authors mount a sophisticated multidisciplinary attack on the central tenets of the vibration theory using synthetic organic chemistry, heterologous expression of olfactory receptors, and theoretical considerations to find no evidence to support the vibration theory of smell." While Turin comments that Block used "cells in a dish rather than within whole organisms" and that "expressing an olfactory receptor in human embryonic kidney cells doesn't adequately reconstitute the complex nature of olfaction...", Vosshall responds "Embryonic kidney cells are not identical to the cells in the nose .. but if you are looking at receptors, it's the best system in the world." In a Letter to the Editor of PNAS, Turin et al. raise concerns about Block et al.〔 and Block et al. respond. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Luca Turin」の詳細全文を読む スポンサード リンク
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