Serendipity and bleach

Interesting new findings on household bleach as a disinfectant. Yes, we know it's a disinfectant. What we don't know is why it is a disinfectant. How exactly does it work? This utilitarian question has just been explored in a paper in the super select and prestigious journal Cell. Here's a bit of background, courtesy the PR flacks at the University of Michigan, whose job it is to publicize the work of their faculty:

In a study published in the Nov. 14 issue of the journal Cell, 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." (Press release, U. of Michigan)

Now Cell is not an applied microbiology journal but a basic science journal. The connection here is the object of study by the Michigan team, a bacterial molecule called heat shock protein 33 (Hsp33). Hsp33 is what we call a chaperone. It "takes care of" other proteins and protects them from adverse or stressful conditions, often escorting them through potentially hostile cellular territory. Chaperones. Besides bleach, perhaps the most common disinfectant is high heat. Heat works by denaturing essential bacterial proteins, making them unfold and glob up in ways that are no longer functional, like egg protein that gets cooked or milk protein that curdles. That's heat disinfection. What about bleach disinfection?

While studying Hsp33 the Michigan researchers discovered that Hsp33 was also protecting against hypochlorite disinfection. They thus discovered that hypochlorite was also affecting 3D protein folding and causing subsequent aggregation (think of it as curdling). An interesting side light is that the human body produces its own version of bleach by generating hypochlorite during the course of inflammation, one way the body combats bacterial infection. When immune cells produce too much hypochlorite they can damage our own cells, not just bacterial cells.

Most readers here don't need a pep talk about the practical benefits of basic research. But it's always nice to have examples.