Three Jewish scientists - two of them Israelis who had emigrated to the U.S. - won the Nobel Prize in Chemistry on Wednesday.

Arieh Warshel, Michael Levitt and Martin Karplus were awarded the top international prize for the development of multiscale models for complex chemical systems.

The Royal Swedish Academy of Sciences on Wednesday said, upon awarding the prize of 8 million crowns ($1.25 million), that their research in the 1970s has helped scientists develop programs that unveil chemical processes such as the purification of exhaust fumes or the photosynthesis in green leaves.

"The work of Karplus, Levitt and Warshel is ground-breaking in that they managed to make Newton's classical physics work side-by-side with the fundamentally different quantum physics," the academy said. "Previously, chemists had to choose to use either/or."

All three winners are American citizens, but also hold dual citizenships. Warshel and Levitt are Israeli citizens, and both studied and worked at the Weizmann Institute in Israel, where Levitt also served as head of the Chemical Physics Department. Warshel was also educated at the Technion. Austrian-born Karplus had fled the Nazis to the U.S. as a child. The Nobel prize was awarded to them on the basis of their research at American universities.

Warshel is a U.S. and Israeli citizen affiliated with the University of Southern California in Los Angeles, Levitt is a U.S., Israeli and British citizen and a professor at the Stanford University School of Medicine, and Karplus is affiliated with the University of Strasbourg, France, and Harvard University.

Pretoria-born Levitt immigrated to Israel at the age of 35 in 1983. He married an Israeli, and worked a few years at the Weizmann Institute until he left for Stanford.

"I can't say I moved there because the conditions in Israel were not satisfactory," Levitt told Israel Army Radio. "In all honesty, to this day I can't quite say why I left the country, my connection to it being very strong. [...] My wife is Israeli, I have two sons living in Israel."

When visiting Israel, Levitt resides in a Rehovot flat, but recently has been considering a move to Tel Aviv, which he called "an amazing city."

"I am being asked all the time what I plan to do with the winnings, but it isn't enough to buy a flat in Tel Aviv with."



'I didn't leave by choice'

Warshel completed his Bachelor’s degree in Chemistry at the Technion – Israel Institute of Technology in 1966.

The person who supervised Warshel in his final project, ‘his first scientific father,’ you could say, was Prof. Ruben Pauncz, who was the first in Israel who dealt with quantum chemistry and calculations of the molecular and atomic systems. Through him, Warshel entered the field of theoretical chemistry.

“I was very happy to hear of Arieh Warshel’s winning [the Nobel Prize]", Pauncz, now 93 years old, told Haaretz. "There were very many students over the years and I remember him somewhat hazily. I remember at some point speaking with Prof. Shneior Lifson of the Weizmann Institute, who supervised his doctorate work, and I remember he was impressed by his intellectual abilities.”

From the Technion, Warshel continued on to the Weizmann Institute of Science, where, in 1970 he completed his Ph. D. degree after three years of work. He spent four years there as a researcher in the Molecular Biology Department, from 1972 to 1976, and then in the late 1970s left for the United States, after not being able to receive tenure at the Institute, according to Speiser.

"The primary reason I left [the Weitzmann Institute] was the difficulties I had in progressing [there]," said Warshel, interviewed Wednesday on Channel 2. "I didn't leave by choice, so I am not a good example for the 'brain drain' issue," he added.

As to his relationship with Israel, Warshel said "I still define myself as an Israeli, but it isn't a clear definition. I have two passports. I speak Hebrew, and sometimes pass to English." But, he concluded his answer, "I act like an Israeli."

"I was sleeping when I got the news," he said. "My wife got a call, and after verifying a Swedish accent was on the other end I was very pleased."

Warshel’s wife Tamar told Israel Radio on Wednesday that her husband “didn’t know how to sell himself well enough to Israeli academia,” when asked about his leaving Israel.

Benny Shalev, Warshel’s brother, spoke to him after the announcement. "He was very excited – like someone who won the Nobel Prize. He may not have been completely surprised since he has been a candidate to receive the prize for a few years already, but it is still a very nice surprise,” Shalev told Haaretz.

Warshel visits Israel once a year and was last here three months ago, said his brother. “He came to lecture at Tel Aviv University and Weizmann Institute.” As to the reasons Warshel left Weizmann, Shalev said: “There are a lot of smart people in Israel and at the same time there was not a job - so he left.”

Warshel won the prize for his development of computer programs that describe the processes of complex chemical and biological systems using quantum mechanical and classical models, explained Prof. Alon Hoffman, the dean of the Schulich Faculty of Chemistry at the Technion.

“Today, in biological systems we are trying to understand how proteins work and how drugs work, for example, on proteins. With the aid of these [computer] programs we can predict the nature of the interaction between the protein and the drug, the responses of the active ingredients, etc. To predict the processes using computerized methods has great importance and it allows the development of new materials and drugs,” said Hoffman.

"In short, what we developed is a method which requires computers to look, to take the structure of the protein and then to eventually understand how exactly it does what it does," Warshel said. When scientists wanted to simulate complex chemical processes on computers, they used to have to choose between software that was based on quantum physics, which applies on the scale of an atom, or classical Newtonian physics, which operates at larger scales. The academy said the three laureates developed computer models that "opened a gate between these two worlds."

While quantum mechanics is more accurate, it is impossible to use on large molecules because the equations are too complex to solve. By using quantum mechanics only for key parts of molecules and classical physics for the rest, the blended approach delivers the accuracy of the quantum approach with manageable computations.

“They certainly deserve the prize. They are trailblazers and to a great extent they founded this field,” said Prof. Hanoch Senderowitz of the chemistry department at Bar-Ilan University, who also works in the area of computerized models of chemical and biological systems.

“The specific field which they specialize in is molecular dynamics and in their first simulation they ran on biological systems. To receive a Nobel Prize in Chemistry in a theoretical field is exceptional,” said Senderowitz.

“The great majority of Nobel Prize winners are experimentalists. I think that this is mostly because people have finally understood the importance of this field and the things it can bring. For people in this field, international recognition is important, because we are talking about a computing tool that always went hand in hand with the experimental work. When you develop a computer model you always validate it against experimental results, since only after you validate it a great number of times can you achieve results,” explained Senderowitz.

Chemistry was the third of this year's Nobel prizes, medicine and physics were already awarded. The prizes for achievements in science, literature and peace were first awarded in 1901 in accordance with the will of businessman and dynamite inventor Alfred Nobel.

Israel's history of Nobel Prizes

Israel has an impressive showing when it comes to Nobel winners, with 11 laureates in its 65-year history. Most recently, Israeli scientist Daniel Shechtman won the Nobel Prize in Chemistry in 2011, just two years after Ada Yonath won the same award in 2009. Other Israelis to have won the prestigious prize in Chemistry were Aaron Ciechanover and Avram Hershko in 2004. Three Israeli politicians have also won the Nobel Prize for peace - Menachem Begin in 1978, and Shimon Peres and Yitzhak Rabin in 1994.

The other Israeli Nobel laureates are Robert Aumann and Daniel Kahneman, who won the prize in economic sciences in 2005 and 2002 respectively, and Shmuel Yosef Agnon, who won the prize in literature in 1966.

Open gallery view Martin Karplus, Michael Levitt and Arieh Warshel, the three laureates of the 2013 Nobel Prize for Chemistry, is seen on a screen during the announcement of the winners, Stockholm October 9, 2013. Credit: Reuters

Open gallery view Israeli Arieh Warshel at his Los Angeles home after learning he won the Nobel chemistry prize, October 9, 2013. Credit: Reuters