such as "Introduction", "Conclusion"..etc
When chemists want to produce a lot of a substance -- such as a newly
designed drug -- they often turn to catalysts, molecules that speed
Many jobs require highly specialized catalysts, and finding one in
just the right shape to connect with certain molecules can be
difficult. Natural catalysts, such as enzymes in the human body that
help us digest food, get around this problem by shape-shifting to suit
the task at hand.
Chemists have made little progress in getting synthetic molecules to mimic this shape shifting behavior -- until now.
Ohio State University chemists have created a synthetic catalyst
that can fold its molecular structure into a specific shape for a
specific job, similar to natural catalysts.
In laboratory tests, researchers were able to cause a synthetic
catalyst -- an enzyme-like molecule that enables hydrogenation, a
reaction used to transform fats in the food industry -- to fold itself
into a specific shape, or into its mirror image.
Being able to quickly produce a catalyst of a particular shape would
be a boon for the pharmaceutical and chemical industries, said Jonathan
Parquette, professor of chemistry at Ohio State.
The nature of the fold in a molecule determines its shape and
function, he explained. Natural catalysts reconfigure themselves over
and over again in response to different chemical cues -- as enzymes do
in the body, for example.
When scientists need a catalyst of a particular shape or function,
they synthesize it through a process that involves a lot of trial and
"It's not uncommon to have to synthesize dozens of different
catalysts before you get the shape you're looking for," Parquette said.
"Probably the most important contribution this research makes is that
it might give scientists a quick and easy way to get the catalyst that
The catalyst in this study is just a prototype for all the other
molecules that the chemists hope to make, said co-author and professor
of chemistry T.V. RajanBabu.
"Eventually, we want to make catalysts for many other reactions
using the fundamental principles we unearthed here," RajanBabu said.
For this study, Parquette, RajanBabu, and postdoctoral researcher
Jianfeng Yu synthesized batches of a hydrogenation catalyst in the lab
and coaxed the molecules to change shape.
The technique that the chemists developed amounts to nudging certain
atoms on the periphery of the catalyst molecule in just the right way
to initiate a change in shape. The change propagates to a key chemical
bond in the middle of the molecule. That bond swings like a hinge, to
initiate a twist in one particular direction that spreads throughout
the rest of the molecule.
Parquette offered a concrete analogy for the effect.
"Think of the Radio City Rockettes dance line. The first Rockette
kicks her leg in one direction, and the rest of them kick the same leg
in the same direction -- all the way down the line. A change in shape
that starts at one end of a molecule will propagate smoothly all the
way to the other end."
In tests, the chemists caused the catalysts to twist one way or the
other, either to form one chemical product or its mirror image. They
confirmed the shape of the molecules at each step using techniques such
as nuclear magnetic resonance spectroscopy.
That's what the Ohio State chemists find most exciting: the molecule
does not maintain only one shape. Depending on its surroundings -- the
chemical "nudges" that it receives on the outside -- it will adjust.
"For many chemical reactions to work, molecules must be able to fit
a catalyst like a hand fits a glove," RajanBabu said. "Our synthetic
molecules are special because they’re flexible. It doesn't matter if
the hand is a small hand or a big hand, the 'glove' will change its
shape to fit it, as long as there is even a slight chemical preference
for one of the hands. The 'flexible glove' will find a way to make a
better fit, and so it will assist in specifically making one of the
mirror image forms.”
Despite decades of research, scientists aren't sure exactly how this
kind of propagation works. It may have something to do with the
polarity of different parts of the molecule, or the chemical
environment around the edges of the molecule.
But Parquette says the new study demonstrates that propagation can
be used to make synthetic catalysts change shape quickly and
efficiently -- an idea that wasn't apparent before. The use of
adaptable synthetic molecules may even speed the discovery of new
The study appears in the June 25 issue of the Journal of the
American Chemical Society. This work was funded by the National
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