Study of bacterial enzyme reveals one key to cancer cel...( WINSTON-SALEM N.C. An enzyme that hel...)

Leslie B. Poole, Ph.D., of Wake Forest University Baptist Medical Center said the explanation begins with the way that bacteria -- such as one that causes food poisoning -- use the enzyme to combat hydrogen peroxide. Hydrogen peroxide, best known as hair bleach or as an antiseptic, is toxic to cells and is one weapon that the body's white blood cells release in an attempt to kill invaders.

Bacteria such as salmonella use the enzyme, called a peroxiredoxin, to inactivate the hydrogen peroxide coming from the white blood cells.

In the April 25th issue of Science, Poole, associate professor of biochemistry, and her colleagues at Oregon State University describe how the same group of peroxiredoxin enzymes work differently in people and other mammals. The enzyme becomes the biochemical switch that keeps the amount of hydrogen peroxide in the body low, but allows it to increase when it is used for intracellular signaling.

The body's cells respond to their environment by generating signals to communicate between one another and between molecules inside the cells, Poole said.

"Hydrogen peroxide is an effective signaling molecule because it is rapidly produced, is reactive and is easily controlled by antioxidant enzymes," Poole said. The complex signaling pathways occur in mammals but not in bacteria.

What determines whether hydrogen peroxide acts as a dangerous oxidant or as a signal? The investigators propose that the peroxiredoxin enzyme controls the floodgates, keeping resting levels of hydrogen peroxide low, while permitting higher levels for signaling.

After studying the enzyme using Oregon State's single crystal X-ray diffractometer, Poole and her colleagues found that related pe
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Contact: Robert Conn
rconn@wfubmc.edu
336-716-4587
Wake Forest University Baptist Medical Center
24-Apr-2003