快猫短视频

THE abnormal protein deposits that clog the brains of Alzheimer鈥檚 patients
probably damage nerve cells by producing the toxic chemical hydrogen peroxide,
new research suggests. Experts say this raises hopes that it might be possible
to treat the disease by blocking this fairly simple chemical.

In Alzheimer鈥檚 disease, an abnormal form of beta-amyloid protein forms in the
brain. 快猫短视频s already knew that cells containing this protein also have
raised levels of the powerful oxidising agent hydrogen peroxide. However, it was
unclear why this was. To find out more, scientists from Harvard Medical School
and the University of Heidelberg looked at the chemical reactions in these cells
by studying changes in the way they absorbed light and fluoresced.

The researchers discovered that when abnormal beta-amyloid binds to iron andcopper, the metal ions donate electrons to dissolved oxygen (
Biochemistry, vol 99, p 438). Oxygen molecules with two excess negative
charges then react with hydrogen ions to form hydrogen peroxide. The team also
showed that the type of beta-amyloid associated with the most aggressive form of
Alzheimer鈥檚 was the best at binding copper and iron鈥攁nd hence at
generating peroxide鈥攕uggesting that this reaction is a major factor in
causing the brain damage.

鈥淯ltimately we would like to be able to interrupt this process,鈥� says team
member Ashley Bush of Harvard Medical School in Charlestown, Massachusetts. 鈥淭he
sites where the copper and iron bind could be an easy target.鈥� He adds that
scientists will first need to figure out the three-dimensional structure of the
binding site.

The new evidence that the generation of peroxide may be involved in the
disease process fits in with other observations, Bush says. Earlier studies
showed that antioxidants such as vitamin E offer significant protection to
people who are developing Alzheimer鈥檚.