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American, Japanese and Swiss scientists won the Nobel Prize in chemistry Wednesday for inventing techniques used to identify and analyze proteins, advances that revolutionized the hunt for new medicines.

The techniques are also proving useful for diagnosing some cancers.

American John B. Fenn, 85, of Virginia Commonwealth University in Richmond, and Koichi Tanaka, 43, of Shimadzu Corp. in Kyoto, Japan, will share half of the $1 million prize. The other half of the prize goes to Kurt Wuethrich, 64, a scientist with the Swiss Federal Institute of Technology in Zurich and the Scripps Research Institute in San Diego, Calif.

Because of their work, "chemists can now rapidly and reliably identify what proteins a sample contains," the Royal Swedish Academy of Sciences said.

"They can also produce three-dimensional images of protein molecules in solution. Hence, scientists can both 'see' the proteins and understand how they function in the cells."

Fenn and Tanaka produced their breakthroughs in the late 1980s, transforming an analysis technique called mass spectrometry, which lets scientists rapidly identify a substance through its mass. Mass spectrometry is used in tests for doping and illegal drugs, for example.

The technique had been used on small or medium-sized molecules for much of the 20th Century. To extend the technique to large molecules, scientists have to make the individual molecules separate and spread out as a cloud in a gas without losing their original structure. Fenn and Tanaka were honored for finding two ways to accomplish that.

"Can you imagine? This happens to so few people," Fenn said when reached at his home in Richmond by The Associated Press. "So many other scientists dream about it. The odds are one in 100,000 or one in a millon."

Wuethrich was honored for improving a technique called nuclear magnetic resonance. The technique allows scientists to develop three-dimensional images of molecules in a solution, which is the natural environment of a protein in a cell.

Wuethrich's work allowed the technique to be used on large molecules like proteins. The first complete protein structure to be determined with his method was achieved in 1985.

Reached in Zurich, Wuethrich said he was "delighted and surprised" at being awarded the prize.

"I am glad that such a prize is coming to Switzerland," he told The Associated Press. "At a time when so much seems to be going wrong, this shows that certain things also have gone right."

The Nobel science awards were to culminate later Wednesday with the announcement of the economics prize, the only award not established in the will of Swedish industrialist Alfred Nobel, the inventor of dynamite.

The winner of the Nobel Prize in literature was to be named on Thursday in Stockholm and the Nobel Peace Prize was to be announced Friday in Oslo, Norway.

The prizes for medicine and physics were announced earlier this week.

For the second year in a row, the academy decided to award the chemistry and physics honors separately, changing a yearslong practice of announcing them the same day after determining that pairing the awards made it too easy for one to be overlooked.

The medicine, physics, chemistry, literature and peace prizes were first awarded in 1901. The Nobel Memorial Prize in Economic Sciences was established separately in 1968 by the Swedish central bank, but it is grouped with the other awards.

Nobel Foundation statutes stipulate that no more than three winners can share a prize and the scientific committees often choose the maximum number, finding it hard to single out researchers. Often the awards are given for discoveries made after decades of research.

Nobel gave little guidance other than to say the chemistry prize should go to those who "shall have conferred the greatest benefit on mankind" and "shall have made the most important chemical discovery or improvement."

The prizes are presented to the winners on Dec. 10, the anniversary of Nobel's death in 1896.