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There are many compounds that taste sweet. Many of the artificial ones taste much sweeter than natural sugars (which is why they contribute little to energy intake when use as sweeteners).

A range of sweeteners is shown in the figure below:

structures of common sweetners

Structurally there are common features for some. We can see why sucralose (a non-metabolisable sweetener based on sucrose) might taste sweet. Rebaudioside a (a major ingredient of the sugar substitute Steria) shares some of those features. But the very sweet artificial sweeteners seem to have less in common.

Do we know what makes molecules generate the sensation of sweetness? Which features matter and why are some sweeter than others?

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  • $\begingroup$ We don't exactly know what makes molecules smell good or bad, which is why companies that look for such molecules still have "the guy with the golden nose". I think it's something similar with our taste buds. $\endgroup$ – tschoppi Jan 10 '14 at 9:53
  • $\begingroup$ (Please be noted that your bottom left structure ‘has a typo’ and is rather 6′-deoxyrebaudioside A; and another typo is in “Steria”.) $\endgroup$ – mykhal Aug 22 '18 at 7:26
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For humans, the "sweet taste buds" are the T1R2+T1R3 & T1R3+T1R3 G-protein coupled receptors.

Chemicals that are sweet are the ones that can bind to these receptors. We know some structures that tend to do this, namely ketones and aldehydes (carbonyl groups).

However, there are chemicals that are sweet that we do not know the mechanism for, such as Curculin, which is up to ~2000 times sweeter than sucrose by weight.

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  • $\begingroup$ While technically interesting to a biochemist, this doesn't tell me anything useful about the detailed molecular features of molecules that taste sweet. Could you explain furter or give more detail. $\endgroup$ – matt_black Jan 10 '14 at 8:08
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    $\begingroup$ In response to: "Do we know what makes molecules generate the sensation of sweetness?" Yes, their affinity to bind to the aforementioned receptors, and carbonyl groups (ketones and aldehydes) are typical indicators of sweetness. And the topic isn't completely figured out, e.g. why Curculin is sweet is unknown. $\endgroup$ – rch Jan 10 '14 at 8:50
  • $\begingroup$ ^ Grammar weirdness; I mean a. their affinity to bind to the receptors, which may not have told you anything. $\endgroup$ – rch Jan 10 '14 at 9:09
  • $\begingroup$ Pressed enter by accident. Apologies! b. molecules that do this tend to have aldehyde/ketone groups on them. My last point was simply that we currently can't enumerate all the groups that can bind to the active sites of these receptors. Sorry if it wasn't too much help. $\endgroup$ – rch Jan 10 '14 at 9:16
  • $\begingroup$ @rch You may want to incorporate the comments into the answer :) $\endgroup$ – ManishEarth Jan 11 '14 at 10:57

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