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Sweetness Receptor Site:
The current working hypothesis the is three-point attachment
theory (AH-B-X). This theory suggests that there are three specifc
areas of the receptor site.
Note: The model receptor site is this author's conception
and is based only very loosely on theory and geometry of the
molecules. It is only useful for students' initial conceptions
of the fit of a molecule into a receptor site.
Area (AH+): This area contains functional groups such
as an alcohol, amine, or some other goup that has hydrogens available
to hydrogen bond to some partially negative atom such as an oxygen
on the sweet molecule. (See the acid group (COO-) on aspartame
on left.)
Area (B -): This area contains functional groups such
as an alcohol, acid, or some other goup that has a partially
negative oxygen available to hydrogen bond to some partially
positive atom such as hydrogen on the sweet molecule. (See the
amine group (NH3+) on aspartame on left.)
Area (X): This area is more or less perpendicular to
the other two areas interacts through hydrophobic or non-polar
properties. The receptor area is non-polar and the area on the
sweet molecule is also non-polar. (See the benzene ring on aspartame
on left.)
It seems that all of the sweet molecules most have at least
two of these properties, but there may be others as well. This
interaction with the receptor site may be somewhat hard to see
in some of the sweet molecules.
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