Bleach has been sanitizing and killing germs(細菌)for more than 200 years, but only now have scientists discovered how the chemical compound actually works. A team of researchers studying a bacterial protein called heat shock protein 33, which helps to stabilize other cellular proteins when exposed to high temperatures, found that the active ingredient in bleach affects proteins in much the same way that high temperature, or fever, does. Bleach’s hypochlorous acid(次亜塩素酸)causes bacterial proteins to clump up, inactivating them and killing the bacteria. The human immune system also produces hypochlorous acid in response to infection, but the substance does not discriminate between foreign invaders and human tissue and attacks both.