New Clue to the Cause of Alzheimer's, Science
Excerpt: "The beauty of this experimental study is
that motion and temperature are inextricably linked, and by
understanding how motion changes in response to temperature, you
understand more about the motions themselves," said Andrew Lee,
PhD, a researcher who worked on the study with Wand at Penn as a
postdoctoral fellow before taking a faculty position at the
University of North Carolina. He added: "The common thinking has
been that the structure of proteins dictates their functions, and
that each one has a different biochemical task. But they aren't
static structures -- they fluctuate, and that these fluctuations
are also critical for protein activity."
In their research, Wand and Lee found the calmodulin protein
has three distinct bands (or preferred magnitudes) of motion on a
subnanosecond time scale, a richness of variation that was not
previously known. Further, when they compared those findings with
existing data on other proteins that had been studied at single
temperatures, Wand and Lee discovered the same spectrum of motion.
This suggests that the range of motion is a general fundamental
property of proteins.
According to Wand, the research findings also suggests an
explanation for the "glass transition" characteristic of proteins
-- the feature that makes proteins respond to heat in the same
fashion as glass. (The onset of dynamics in the glass transition
is often associated with the attainment of biological activity.)
"The key word is 'entropy' -- the ability to assume multiple
states," Wand said. "For a long time, people assumed proteins
didn't have significant entropy, so they discounted its potential
functional role. In fact, proteins have a lot more ways to
accomplish their functions than we realized. This dynamism has
central significance for how proteins may work."