Study finds how lysozyme protein in tears annihilates dangerous bacteria

January 19, 2012
Structure of Lysozyme. Image: Wikipedia.

A disease-fighting protein in our teardrops has been tethered to a tiny transistor, enabling UC Irvine scientists to discover exactly how it destroys dangerous bacteria. The research could prove critical to long-term work aimed at diagnosing cancers and other illnesses in their very early stages.

Ever since Nobel laureate found that human tears contain antiseptic proteins called lysozymes about a century ago, scientists have tried to solve the mystery of how they could relentlessly wipe out far larger bacteria. It turns out that lysozymes have jaws that latch on and chomp through rows of cell walls like someone hungrily devouring an ear of corn, according to findings that will be published Jan. 20 in the journal Science.

"Those jaws chew apart the walls of the bacteria that are trying to get into your eyes and infect them," said and chemistry professor Gregory Weiss, who co-led the project with associate professor of physics & astronomy Philip Collins.

The researchers decoded the protein's behavior by building one of the world's smallest – 25 times smaller than similar circuitry in laptop computers or smartphones. Individual lysozymes were glued to the live wire, and its eating activities were monitored.

"Our circuits are molecule-sized microphones," Collins said. "It's just like a stethoscope listening to your heart, except we're listening to a single molecule of ."

It took years for the UCI scientists to assemble the transistor and attach single-molecule teardrop proteins. The scientists hope the same novel technology can be used to detect cancerous molecules. It could take a decade to figure out, but would be well worth it, said Weiss, who lost his father to lung cancer.

"If we can detect single molecules associated with cancer, then that means we'd be able to detect it very, very early," Weiss said. "That would be very exciting, because we know that if we treat cancer early, it will be much more successful, patients will be cured much faster, and costs will be much less."

Explore further: Researchers unveil new method for detecting lung cancer

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4.5 / 5 (2) Jan 19, 2012
Really changes my perspective on that scene in Terminator 2 when the terminator asks John Connor why humans cry. What he should have said is "Oh, that. It's a defense mechanism of our innate immune system. We cry to secrete lysozyme-containing tears to fight bacterial infections."
3 / 5 (2) Jan 19, 2012
But it only answers how our eyes' immune system works, not why we cry when stressed.

Why we over-produce tears when crying remains an enduring mystery... is it for communicative emphasis, to elicit sympathy or mercy? Was a distant ancestor exposed to a common stressor that increased the risk of eye infection or dehydration, cementing a vestigial response to emotional stress per se..? Or is it just some kind of incidental short-cicruit?

Fascinating discovery though.. microbial jaws of death.. wonder what other uses the mechanism might have..?
1 / 5 (1) Jan 19, 2012
Pretend - as hypothesis - that excessive tearing enhances and is the perfect analogy to the purpose researchers have assigned Vitamine E to artificial lenses after surgery:


And not wishing to sound flippant at all;
Do lysomzmes ingest the contents of their 'bites'?
1 / 5 (1) Jan 20, 2012 anaesthetic? So we produce tears when crying because of a general pain-relief response under stress? That sounds plausible, an interesting point.....
1 / 5 (1) Jan 20, 2012
Opponents to this plausibility will flame:

Yes, yes...all those tearless life forms with sight will just have to do without such a wonderful general pain-relief response. Not to mention asserting all other life forms with tears have become so sensitive, no other pain-relief response will do. A macroscopic response in the broadest sense.

As I read your comment, I spontaneously thought of the article. And a spontaneous, plausible hypothesis to your intriguing, provocative questions.

The dissenters/'dismissers' are lurking. I welcome them as long as they don't flame empty handed - without an even more compelling alternative.

And the puzzle is revealed some day as mere conjecture:
Mere correlation asserted from observed cause and effect.

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