Tears rip through bacteria, scientists find

By Carrie Johnson Weimar • Published: April 25th, 2012
Category: Health in a Heartbeat

Human tears can be a powerful weapon. Anyone who has tried to calm a crying toddler or placate an emotional friend knows that. But did you know that tears do more than just slice through emotions? Researchers from the University of California-Irvine say the proteins in these little water drops can also tear through bacteria.

The scientists examined lysozymes [lye-suh-zymes], which are enzymes found in your tears that are capable of breaking down the cell walls of bacteria. The enzyme’s antiseptic properties were first discovered back in the 1920s by Scottish biologist and pharmacologist Alexander Fleming, the man who also discovered penicillin. However, no one knew exactly how lysozymes were capable of destroying bacteria so much larger than them. For example, white blood cells — the body’s first line of defense from bacteria — destroying bacteria by engulfing them. Lysozymes had to be far more subtle.

What the UC-Irvine scientists found sounds like something straight out of a horror movie. They discovered that each molecule of the protein acts like a voracious set of jaws that chomps into cell walls and won’t let go. As a result, lysozymes slice through bacteria as easily as a knife slipping through butter.

Unraveling this mystery wasn’t easy. The proteins bind with the molecules and undergo tiny changes as they tear through the walls. But the movements are so miniscule, they can be hard to track. So the scientists built a tiny transistor and attached it to a single protein molecule so they could monitor how it changes.

Besides begin really cool, what’s the benefit of this discovery? Scientists hope they can one day use this method to detect cancerous molecules earlier than current techniques. Now if only they could turn the killer lysozymes on cancer cells, too.