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Synthetic Sugar
Complex organic chemistry and the chemistry of carbohydrates are, well,
complex. A profile of Albertan Raymond Lemieux's achievements in the
synthesis of carbohydrates and configuration of such molecules would
mean little to anyone without an advanced understanding of organic
chemistry.
However, consider the following: When you pick up a peach, your brain
processes the experience in terms of three dimensions. You can see and
feel the fruit's height, width and depth. You can tell if it's juicy. You
can observe a bruise, or turn it around and tell if the other side is mouldy. If you were to look closer at that peach, down at the molecular
level, you would see that the molecules, the building blocks of this
peach, also come in three dimensions.
The peach is made up of a variety of molecules, many of which are
sugars. Sugar is a carbohydrate. Some sugars, such as sucrose, are
simple in design. Others, such as oligosaccharides, are more
complicated, and polysaccharides, are the most complex.
When Lemieux began his research and study, the existing scientific
understanding of these sugar molecules was limited. Chemists had been
able to synthesize, or chemically fabricate, other molecules, but no one
had been able to accomplish the same feat with sucrose, common table
sugar.
Lemieux realized there was very little knowledge of the shape of the
sugar molecules and that knowing this was the key to truly understanding
them. Once he understood their shape, he believed, he would be able to
chemically fabricate them. Thanks to this insight, in 1953 at the
National Research Council's Saskatoon laboratory, Lemieux became the
first person to successfully synthesize sucrose.
Although the synthesis of sucrose has commonly been considered the apex
of organic chemistry achievements, the molecule itself is very simple.
With his success in Saskatoon, Lemieux continued his explorations with
sugar, turning to the more complicated carbohydrates. With his interest
in the shape of molecules and the research and help of colleagues,
Lemieux synthesized the more complex sugar oligosaccharides.
This achievement has proven to be of immeasurable benefit to the medical
world. Oligosaccharides are found in the thousands on the surface of red
blood cells, organs and other human tissues. When an organ transplant
fails, it is usually because the body of the person receiving the
transplant, the host, rejects the donor organ by producing antibodies to
remove the foreign "invader." This occurs because the sugar molecules
from one body differ from the other. Once these molecules meet, the host
recognizes that the shape of the foreign molecule is different and
rejection can occur, with the donor organ destroyed within hours,
possibly minutes.
Through the synthesis of oligosaccharides and understanding how their
shape affects their functions, Lemieux and other chemists have been able
to create antigens, which promote organ transplants.
"His work has been the key factor in converting this area of research
from an academic specialization to one of great practical significance
in important fields as blood typing and medical chemistry."
Comments of the awarding committee upon presenting to Raymond Lemieux
the 1992 Albert Einstein "World Award of Science"
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