The scientists need crystals preferably nice, big ones to stick in the path of an X-ray beam at Argonne National Laboratory in Chicago. (If the crystal is a good one, and all the atoms are lined up in a repeating array, the scattered X-rays will produce a clear pattern of spots.)
Embedded in that pattern is the mathematical information needed to back-calculate to the position of the atoms in the protein, a process a bit like throwing a handful of pebbles in a lake and then calculating where they landed by the pattern of waves arriving at the shoreline.
Lee got the PMT from Haemonchus contortus to crystallize first, but there were technical issues with the diffraction pattern that would have made solving it technically and computationally very demanding.
"When the Plasmodium enzyme finally crystallized, Soon got four crystals kind of stacked on top of each other and each of them was paper thin," Jez says.
"I never thought it would work, but we took them to Argonne anyway and he actually did surgery under the microscope and cracked off a little tiny piece of it."
To everyone's surprise, he got a clean diffraction pattern from the crystal. "Because the Plasmodium enzyme was the smallest one and the easiest to work on, we pushed that one first," Jez says.
The moment of truth
"Once we had a Plasmodium crystal that was diffracting really well, we could try back-calculating to see whether we could extract the atom positions from the data," Jez says.
After the computer finished its calculations, Lee clicked a mouse button to see the results, which would reveal whether his years of work finally would pay of
|Contact: Diana Lutz|
Washington University in St. Louis