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Imaging opioids’
molecular magic
By Devin Powell
Proteins turned on by opium and similar
substances in the body have been caught
in action. Two new snapshots show how
cellular proteins lasso molecules in the
opium family, revealing the 3-D structure of such pairings for the first time.
The work represents a major step
toward designing drugs that lack opioids’
nasty side effects, two teams of researchers report online March 21 in Nature.
“Everyone in the field has been wait-
ing to see these crystal structures,” says
Jane Aldrich, a medicinal chemist at the
University of Kansas in Lawrence. “Now
we can look at how particular parts of the
molecules interact.”
Proteins that respond to opium and
opiumlike molecules protrude from cell
surfaces in the brain, spinal cord and
gut. Hormones and brain chemicals such
as endorphins attach to these recep-
tor molecules to control pain, regulate
breathing and change mood.
Knowing how a morphinelike molecule
fits in the pocket of the protein it inter-
acts with (blue background) could help
scientists find less-addictive painkillers.
In the second study, Seva Katritch of
the Scripps Research Institute in La Jolla,
Calif., and colleagues looked at how the
drug JDTic deactivates a kappa opioid
receptor, which is turned on by the hallucinogen salvinorin A. “Kappa opioid
receptors are especially interesting
because of their ... role in regulation of
stress,” says Katritch. JDTic is being
tested as a treatment for drug abuse.
Polymer power drives tiny reaction
Squeezing plastic ingredient generates energy for chemistry
By Rachel Ehrenberg
In the quest to wring energy from every
source imaginable, scientists are putting the squeeze on a common plastic
ingredient. Applying force to polymers
in water generates enough energy to
drive chemical reactions, a team reports
online March 1 in Angewandte Chemie.
The technique offers a way to harness
the wisps of unused energy generated
by everyday endeavors, like walking or
compacting plastic bags. Capturing such
energy could lead to cheap, clean ways to
sanitize a small container of water, or to
run a simple lab-bench reaction.
Scientists knew that when mechanical
Energy generated by walking in this
sneaker created free radicals, driving a
reaction to make the polymer sole glow.
force is applied to a polymer, bonds can
break to generate free radicals, molecules with unpaired electrons. The
new work shows that when a polymer
is squeezed in water, the free radicals migrate and react with the water,
generating enough hydrogen peroxide
to spur other reactions.
The researchers squeezed various
polymers, including the silicon-based
polymer PDMS. Squeezing PDMS tubes
filled with water containing gold and
silver salts created gold and silver nanoparticles. The researchers also injected
the sole of a Nike LeBron sneaker with
water and a compound that fluoresces
when cleaved. Half an hour of walking
produced free radicals that made enough
hydrogen peroxide to cleave the fluorescing compound and make the sole glow.
“People predicted that the energy
efficiency would be minute,” says study
coauthor Bartosz Grzybowski of Northwestern University. But converting the
mechanical energy of polymer squeezing
into energy for driving reactions can be
as efficient as 30 percent.
FROM TOP: KOBILKA LAB; H. T. BAYTEKIN AND B. BAYTEKIN
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