Science-- lost and found

Topic started by Ellen (@ on Fri May 2 16:21:52 .
All times in EST +10:30 for IST.

I got curious from the "Does God exist" thread.

"De gustibus non est disputandum". (There is no disputing in matters of taste.)

>>Sweetness comes from a specific molecular structure; and one can analyse it by molecular analysis (biochemistry). (Rohit)>>

This stuff, I totally copied and pasted, IOW, not my own!

Taste transduction involves the interaction of molecules with taste receptor cells, which reside in specialized structures known as taste buds...

The sweet taste is more complicated, as shown by some of the compounds listed in Table III. There is evidence that these act on the same set of receptors, since the sweet taste of all of them is blocked by pre-treatment of the tongue with gymnemic acid, an extract of the plant Gymnema sylvestre (Bartoshuk et al., 1969). This compound tastes like strong tea, and rinsing the tongue blocks all sweet tastes for about one hour without affecting salt, sour or bitter. The gymnemic acid occupies the sweet receptors in the mouth, preventing other sweet-tasting compounds from stimulating them.

Table III. Sweet-tasting compounds
Alcohols OH-CH2-CH2-OH
Glycols HO-C=C-OH
Saccharin CO
/ \ / \
| | N
\ / \ /
Leucine (CH3)2-CH-CH2-CH(NH2)-COOH
Lead acetate Pb(CH3-COO -)3
Beryllium chloride BeCl2
Aspartame N-Aspartylphenylalanine

The sweet taste may be due to the formation of a double hydrogen bond between the tastant molecule and receptor complex on the surface of the taste cell, as shown in Figure 14. This theory was put forth by Shallenberger (1971), and succeeded in explaining the sweet tastes of several different compounds, some ionized and some not. It is assumed that the tastant has a hydrogen-donating site within 3 Ångstroms of a hydrogen-accepting site, and that these have complementary donating and accepting sites on the receptor membrane, also spaced 3 Ångstroms apart.

For instance, in saccharine the nitrogen atom can donate a hydrogen ion and the oxygen can accept. Metal compounds in solution are hydrated and in this configuration can donate and accept H-ions.



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