Research 2006
Small Particles, Big Consequences:
Understanding the Differences Between Protein Molecules
Doug Craig
Associate Professor, Chemistry
While we all know that every person is unique, researchers who study the chemistry of the human body are finding that even the cells and molecules that make up a person may be unique.
Associate Professor Doug Craig studies enzymes, the protein molecules that control the chemistry in the body. Enzymes do the grunt work: building and repairing cells, keeping the heart pumping, neurons firing, and nutrients moving. Enzymes keep a body functioning.
Until recently, most enzyme researchers have studied pools of molecules to calculate how an average molecule functions. Craig was one of the first scientists in the world to develop a method for measuring the properties of a single enzyme molecule.
By spacing the enzyme molecules inside a long, thin capillary tube, Craig was able to measure the amount of product made by individual enzyme molecules.
“These are all the same enzyme and they’re all from the same bacteria,” says Craig. Therefore, all the enzyme molecules should perform the same functions in the same way. “Enzymes make a reaction happen—they convert compound A into compound B. But when you measure them, one enzyme molecule might do the same action twice as quickly as another one, even though they’re identical,” he says. “It’s different, and it’s not supposed to be.”
Individual molecules function differently at standard temperatures as well as with changes in temperature and with the amount of chemicals supplied for the reaction. Craig finds that some enzyme molecules are 10 to 50 times better at making their reaction products than others.
“And it’s not just a slight variation,” says Craig. “So the question is: Why would your body go to all this effort to make enzymes all the same, and yet have them all perform differently? That would be inefficient. So maybe your body makes them different on purpose, so that under some conditions enzymes have certain properties and under other conditions they have other properties.”
Craig’s research has implications for drug therapies, many of which target enzymes to improve body function. Already cancer researchers know that not all cancer cells in a tumor are the same and that some respond better to one treatment than to others. If similar logic applies to enzymes, then patients may respond differently to some drug treatments.
Next, Craig and his team plan to compare enzymes manufactured in bacteria versus enzymes manufactured in a test tube to determine if cell-made enzymes are different from those made without a cell.
“This research helps us understand how chemistry is regulated in the body,” says Craig.
To learn more about his research on protein molecules, contact University of Winnipeg faculty member Doug Craig at d.craig@uwinnipeg.ca