By Matthew Dublin
Researchers from the University of Tennessee and the Department of Energy's Oak Ridge National Laboratory are using supercomputer simulations to study a class of proteins involved in drug detoxification.
Jerome Baudry and Yinglong Miao, both of whom are jointly affiliated with ORNL and the University of Tennessee, have performed simulations using the Kraken supercomputer, a 1.17 petaflop Cray XT5 Linux system.
With Kraken, they were able to examine the motions of water molecules in a class of enzymes called P450s, which are sometimes responsible for processing a large fraction of drugs taken by humans.
The simulations modeled how water molecules move in and out of the protein's centrally located active site, enabling the team to clarify an apparent contradiction between experimental evidence and theory that had previously puzzled researchers. X-ray crystallography had displayed only six water molecules present in the active site, whereas experimental observations indicated a higher number of water molecules would be present in the enzyme.
"We simulated what happens in this enzyme over a time scale of 0.3 microseconds, which sounds very fast, but from a scientific point of view, it's a relatively long time," Baudry said. "A lot of things happen at this scale that had never been seen before. It's a computational tour de force to be able to follow that many water molecules for that long."
Water molecules (seen in red) move in and out of the active site (seen in blue) of a P450 enzyme. This class of enzymes is responsible for detoxifying a large fraction of drugs taken by humans.

The Kraken supercomputer:

Their research was published in the Biophysical Journal.