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How bleach kills bacteria

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Staff writer ▼ | November 22, 2008
Developed more than 200 years ago and found in households around the world, chlorine bleach is among the most widely used disinfectants, yet scientists never have understood exactly how the familiar product kills bacteria.
How bleach kills bacteria
How bleach kills bacteriaDeveloped more than 200 years ago and found in households around the world, chlorine bleach is among the most widely used disinfectants, yet scientists never have understood exactly how the familiar product kills bacteria.


New research from the University of Michigan, however, reveals key details in the process by which bleach works its antimicrobial magic. A team led by molecular biologist Ursula Jakob describes a mechanism by which hypochlorite, the active ingredient of household bleach, attacks essential bacterial proteins, ultimately killing the bugs.

"As so often happens in science, we did not set out to address this question," said Jakob, an associate professor of molecular, cellular and developmental biology. "But when we stumbled on the answer midway through a different project, we were all very excited."

Jakob and her team were studying a bacterial protein known as heat shock protein 33 (Hsp33), which is classified as a molecular chaperone, says the news from the University of Michigan. The main job of chaperones is to protect proteins from unfavorable interactions, a function that's particularly important when cells are under conditions of stress, such as the high temperatures that result from fever.

"At high temperatures, proteins begin to lose their three-dimensional molecular structure and start to clump together and form large, insoluble aggregates, just like when you boil an egg," said Jeannette Winter. And like eggs, which once boiled never turn liquid again, aggregated proteins usually remain insoluble, and the stressed cells eventually die.

Jakob and her research team figured out that bleach and high temperatures have very similar effects on proteins. Just like heat, the hypochlorite in bleach causes proteins to lose their structure and form large aggregates. "Many of the proteins that hypochlorite attacks are essential for bacterial growth, so inactivating those proteins likely kills the bacteria," said second author Marianne Ilbert, a postdoctoral fellow in Jakob's lab. These findings are not only important for understanding how bleach keeps our kitchen countertops sanitary, but they may lead to insights into how we fight off bacterial infections.


 

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