Stockholm, Oct. 6 (Reuters): Two Israelis and an American won the 2004 Nobel Prize for Chemistry today for helping to understand how the human body gives the ?kiss of death? to faulty proteins to defend itself from diseases like cancer.

Israelis Aaron Ciechanover and Avram Hershko and American Irwin Rose won the prize for work in the 1980s that could help in the treatment of illnesses like leaukemia and cystic fibrosis by identifying how the body ?degrades? unwanted proteins.

?When the degradation does not work correctly, we fall ill. Cervical cancer and cystic fibrosis are two examples,? said the academy in its citation, adding that such knowledge ?offers an opportunity to develop drugs against these diseases and others?.

The scientists found that proteins which could cause disease are ?labelled? for destruction with a molecule called ubiquitin which dispatches them to the body?s ?waste disposal? units, called proteasomes.

?We are not a building that stays still, we are all the time exchanging our proteins, synthesising and destroying them,? said an elated Ciechanover. ?Some proteins get spoilt. We discovered the process by which the body exercises quality control.?