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Q: "Organic Chemistry in Real Life" ( Answered,   0 Comments )
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Subject: "Organic Chemistry in Real Life"
Category: Science > Biology
Asked by: mostwanted2004-ga
List Price: $10.00
Posted: 21 Jul 2003 10:30 PDT
Expires: 20 Aug 2003 10:30 PDT
Question ID: 233391
If only the D form of glucose is metabolized by the body, can we make zero 
calorie sweeteners from the L isomers of sugars?

I need no more than two (2) pages summary, and I want it before july 25, 2003.
Thank you.
Answer  
Subject: Re: "Organic Chemistry in Real Life"
Answered By: wonko-ga on 21 Jul 2003 11:52 PDT
 
In theory, the answer is yes, according to the following references
that I found.  However, substantial barriers exist in the form of
difficulties in making it at a competitive cost.

"The most interesting potential sweetener from a chemical
point-of-view is left-handed sucrose! Sucrose is optically active, as
are many biologically active molecules, and natural sucrose is
right-handed. The other optical isomer would be sweet but would not be
recognised in the bo[d]y and would thus not be metabolised. However,
the synthesis of this alien form of sucrose (it does not occur
naturally) would be very difficult and it is hard to see it being
produced (even if it were possible) at a cost to compete with other
artificial sweeteners. It is, however, an excellent example of the
importance of optical activity or [the (strikeout)] having the correct
handedness in biology."

http://www.ul.ie/~childsp/CinA/issue50/sweet.html "What's in a
sweetener" Chemistry in Action 50

"Body can metabolize only the D isomer of glucose. This makes the
possibility of developing the L isomer into an alternative sweetener
very enticing."

http://web.kyunghee.ac.kr/~cna/faculty/study/youngyang.htm

"All organically produced glucose rotates the direction of
polarization of light clockwise. This sugar is called d-glucose.
Another sugar, called l-glucose, rotates the direction of polarization
to the left. It can only be made by inorganic chemical synthesis. Both
d-glucose and l-glucose have the same chemical formula: C6H12O6.
However, the atoms in each of these isomers are arranged in a
different pattern. The left-handed sugar (l-glucose) tastes just as
sweet as the right-handed one (d-glucose), but your body can't use it
as an energy source. That's how left-handed sugars can produce
sweetness without calories."

http://www.exploratorium.edu/snacks/rotating_light.html "Rotating
Light" Exploratorium

"There are several hundred different forms of sugar found in nature.
Common table sugar is sucrose, which is a combination of glucose
(dextrose - right-handed sugar) and fructose (levulose - left-handed
sugar). Your body prefers the right-handed variety, so the
carbohydrates in your food goes through a conversion process to
convert it to glucose (blood-sugar), which in turn is distributed
throughout your body, where it is combined with oxygen (oxidized, i.e.
burned) to produce energy, with the by-products of water and
carbon-dioxide, which you breathe out.

Levulose (left-handed) is the form of sugar helpful to diabetics."

http://m2.aol.com/RichClark7/pass/wine/sweet.htm "Sweet Soberness!"

"Levo-sugar it's called, for left-handed.
Levo-sugar is a confusing chemical to the human body. To the tongue,
it
tastes just like regular sugar. But the body has never swallowed
left-handed
sugar and can't digest it.
Levin spent the better part of the 1980s tinkering with left-handed
sugar,
attracting a lot of attention to Biospherics stock, but ultimately
leaving a
bad taste in the mouths of investors. The problem was that the company
was
never able to find a way to make left-handed sugar at a low enough
price to
give the company a high stock price. Every once in a while,
Biospherics
would announce some development in sweetener research, the stock would
jump,
and then it would drift back down.
The pattern continued in the 1990s after Levin shelved levo-sugar and
shifted his team of researchers to tagatose."

http://131.104.232.9/fsnet/2001/4-2001/fs-04-16-01-01.txt FSNET, April
16, 2001

I hope you found the above references helpful.

Sincerely,

Wonko

Search Terms:

"L isomer" sugar sweet
"Left-handed sugar"
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