STOCKHOLM: Two Americans and an Israeli scientist won the 2009 Nobel Prize in chemistry today for atom-by-atom mapping of the protein-making factories within cells — a feat

that has spurred the development of antibiotics.

The Royal Swedish Academy of Sciences said Venkatraman Ramakrishnan, Thomas Steitz and

Israeli Ada Yonath’s work on

ribosomes has been fundamental to the scientific understanding

of life. They will split the $1.4 million award.

Yonath, 70, is the fourth woman to win the Nobel chemistry prize and the first since 1964, when Dorothy Crowfoot Hodgkin of Britain received the award.

“I’m really, really happy,” Yonath said. “I thought it was wonderful when the discovery came. It was a series of discoveries ... We still don’t know every, everything, but we progressed a lot.” Ribosomes are crucial to life because they produce the proteins that control the chemistry of plants, animals and humans. Working separately, the three

laureates used a method called

X-ray crystallography to pinpoint the positions of the hundreds of thousands of atoms that make up the ribosome.

Their three-dimensional models show how different antibiotics bind to ribosomes - an understanding that has helped other researchers develop new drugs to fight bacterial infections.

“These models are now used by scientists in order to develop new antibiotics, directly assisting the saving of lives and decreasing humanity’s suffering,” the academy said in its announcement.

Many of today’s antibiotics cure diseases by blocking the function of bacterial ribosomes, the citation said. “Without functional ribosomes, bacteria cannot survive. This is why ribosomes are such an important target for new antibiotics.” The work was published in 2000. While many Nobel winners are honoured for joint work, this year’s chemistry winners were competing with each other, award committee member Mans Ehrenberg said.

Their work builds on Charles Darwin’s theory of evolution and, more directly, on the work done by James Watson, Francis Crick and Maurice Wilkins, who won the 1962 Nobel Prize in medicine for mapping DNA’s double helix, the citation said.

In 2006, Roger D. Kornberg won the Nobel Prize in chemistry for X-ray structures that showed how information is copied to messenger RNA molecules, which carry information from DNA to the ribosomes.

“Now, one of the last pieces of the puzzles has been added - understanding how proteins are made,” said Professor Gunnar von Heijne of the Swedish Academy of Sciences, the chairman of the Nobel Committee for Chemistry.” Thomas Lane, president of the American Chemical Society, said the award was an example of how chemistry can improve people’s lives.

“For me it’s another example where chemistry is the central science for addressing some of these very big issues,” he said.

“You hear words like ‘ribosome’ and ‘bacteria,’ and you tend to think biology when in fact it’s chemistry at work.”