On the Unpredictability of Odor

Sell, Charles S.

doi:10.1002/anie.200600782

Cited by 168 publications

(143 citation statements)

References 37 publications

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“…They include the entgegen-zusammen (E-Z ) transitions for which cistrans cannot be unambiguously defined. We note that an (E-Z ) transition across a double bond in a carbon chain can make a vast difference to odour perception (Sell 2006). One may contrast the 'creamy, butter, odour' of Z-4-heptanal with the 'aggressive, green and putty-like' odour of its E-isomer.…”

Section: Olfactant Structures: Flexible and Inflexible Moleculesmentioning

confidence: 88%

“…Despite the contentious issue of purity, it is well established that it is the case that (one way or another) many enantiomer pairs smell different (Sell 2006). We might postulate four possible explanations.…”

Section: Classifying Enantiomers and Their Odoursmentioning

confidence: 99%

“…'Osmophoric groups' have been coined as a phrase to describe polar parts of an odorant molecule. Usually, odorants have one strongly polar group and a secondary weaker polar group (Sell 2006). Having discovered one correlation between two rare odorant qualities, namely that there are very few true type 1's and that they are rigid, it is interesting to observe that the same molecules seem only to have one osmophoric group.…”

Section: Structure and Character For Enantiomer Pairsmentioning

confidence: 99%

“…By contrast, it is observed that the type 2 nootkatone exhibits two areas of higher regions of electronegativity about opposite ends of the conjoined rings (at the CaO and CaC), whereas the type 1i geosmin and type 1 tetrahydronootkatone exhibit only one area of electronegativity (about the alcohol and carbonyl group, respectively). Thus, we propose that a combination of rigidity and a sole osmophoric group (Sell 2006) actually renders left-and right-handed odorants superimposable (in the sense that the same atoms exist in similar space) within a receptor. In this case, the receptor is unable to discriminate, thus these unlikely cases we perceive as type 1.…”

Section: Structure and Character For Enantiomer Pairsmentioning

confidence: 99%

“…Also important may be the time spent at the site. Lai et al (2005;Sell 2006) showed that when ligands are fitted to a binding pocket, then, once natural vibratory motion was included, some odorants stayed within the pocket, whereas others moved out. Their results correlated with experiment, in that those that stayed within the domain activated the OR17 receptor, whereas the others did not.…”

Section: How Might Flexibility Affect Olfaction?mentioning

confidence: 99%

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Odour character differences for enantiomers correlate with molecular flexibility

Brookes

Horsfield

Stoneham

2008

J. R. Soc. Interface.

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The olfactory system sensitively discerns scents from many small molecules as the brain analyses signals from nasal receptors. These receptors are selective to some degree, though the mechanism for selectivity is still controversial. Enantiomers, chiral pairs of left-and right-handed structures, are an important class of molecules in assessing proposed mechanisms. We show that there is a correlation between molecular (structural) flexibility and whether or not the left-and right-handed enantiomers smell the same. In particular, for the fairly extensive class of enantiomers with six-membered ring flexibility, enantiomers do not smell the same. There are, of course, significant experimental uncertainties, which we discuss here. We discuss models of receptor selectivity, both those based on shape and those where discrimination is based on other factors, such as electron affinity, proton affinity or vibration frequencies. The differences in scent of these enantiomers appear to be consistent with simple generalizations of a 'swipe card' model in which, while the shape must be good enough, critical information for actuation is a separate factor.

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Section: Olfactant Structures: Flexible and Inflexible Moleculesmentioning

confidence: 88%

Section: Classifying Enantiomers and Their Odoursmentioning

confidence: 99%

Section: Structure and Character For Enantiomer Pairsmentioning

confidence: 99%

Section: Structure and Character For Enantiomer Pairsmentioning

confidence: 99%

Section: How Might Flexibility Affect Olfaction?mentioning

confidence: 99%

See 3 more Smart Citations

Odour character differences for enantiomers correlate with molecular flexibility

Brookes

Horsfield

Stoneham

2008

J. R. Soc. Interface.

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Perfumes

Perring¹

2016

Kirk-Othmer Encyclopedia of Chemical Technology

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This article provides an overview of perfumes from the perspective of the technical specialist and highlights how the growth of the synthetic aroma chemical industry has supported the penetration of perfumes into the majority of consumer products, as either fine fragrances or as functional fragrances. Perfume creation, the surprising scope of fragrance technologies, process research and development, and associated legislative issues are summarized. The article also covers such topics as the analysis of natural products, structure–odor considerations, mood effects of fragrance, and malodor counteraction. Perfume commercialization and how it has evolved in the twenty‐first century, in particular the impact of perfume encapsulation and the filing of ever‐increasing numbers of patents, as well as the vexed question of perfume copyright are also touched on. Finally, it reviews some general business aspects including the market profile and the effect of global safety and environmental legislation on regulation of the industry.

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Olfaction, Chemical Biology of

Sell

2008

Wiley Encyclopedia of Chemical Biology

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Smell is an intriguing sense in many ways. Although it is not the dominant sense in humans, it has affects on emotion and memory which can be very profound. Odor has long baffled chemists who try to model it in mechanistic terms, and a great deal of research has been invested in trying to understand how various features of molecular structure provide different odor characters and intensities. Many models for prediction of odor properties from chemical structure exist, but none are accurate and precise consistently. The reasons for this are now becoming clearer. The greatest breakthroughs in our understanding of olfaction came with the discoveries of the gene family coding for the olfactory receptor proteins (1) and the combinatorial mode of operation of these receptors (2). Odorous molecules enter the nose either from the front, by inhalation, or from the back, by diffusion from the mouth and respiratory tract. In the nose, they interact with an array of receptors. Each receptor type responds to a range of odorants, and each odorant stimulates a range of receptors. The signals thus generated are coded onto centers, known as glomeruli, in the olfactory bulb. The olfactory signals pass on upward through the brain and are interpreted finally, in the cortex, as odor. During the neurotransmission process, many interactions occur between olfactory signals and cortical feedback mechanisms, which include effects from other senses. Therefore, it is not surprising that simple structure/odor correlations are so elusive.

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On the Unpredictability of Odor

Cited by 168 publications

References 37 publications

Odour character differences for enantiomers correlate with molecular flexibility

Odour character differences for enantiomers correlate with molecular flexibility

Perfumes

Olfaction, Chemical Biology of

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