For many people, computers are a great way to insult strangers or look at pictures of cats, but for others they can be an invaluable tool, able to perform millions of calculations in the time it has taken you to read this.
Chemists have long been in need of such a tool. Chemical reactions involve bond breaking where electrons leap from one atom to another, and it is almost impossible for chemists to describe such processes by the very fast programs that treat the atoms and bond as classical balls and sticks. On the other hand it is possible to use quantum mechanical program electronic structure calculations, but such calculations are too expensive to be use din describing reactions in large molecules and proteins.
What Arieh Warshel, and his colleagues and fellow laureates Martin Karplus and Michael Levitt, achieved – starting back in the 1960s when computers were still primitive by modern standards – was the creation of a computer programs that took the best of both classical and quantum physics and merge them into a working system.
These ‘multiscale models’ can, for instance, simulate how a drug couples to its target protein in the body. The computer performs detailed theoretical calculations at a quantum level only on those atoms in the target protein that interact with the drug. The rest of the protein is ‘painted in’ using classical physics.
Scientists can now let computers perform most of the work in accurately predicting chemical processes in very large systems saving time, energy and the materials used in conventional laboratory experiments. Inevitably, such cost-saving software has proved invaluable not only in the medical/pharmaceutical fields but in industrial research, whether by enhancing the performance of catalytic converters on cars or translating the study of natural photosynthesis to improvements in photovoltaic cells for solar panels.
Warshel was born in November 1940 at Kibbutz Sde-Nahum in the Beit She'an Valley in northern Israel (then the British Mandate of Palestine). He served in the tank regiment of the Israeli army during both the Six-Day War of 1967 and the 1973 Yom Kippur War, rising to the rank of captain. He still bears a scar on his right ear from a bullet graze.
He juggled his military duties with his academic studies at the Technion in Haifa, where he elected to study chemistry based on an off-the-cuff suggestion by a friend. He went on to receive his BSc degree, summa cum laude, in 1966 – the same year he married his wife Tamar, with whom he has two daughters. He earned his MSc (1967) and PhD (1969) in chemical physics at the Weizmann Institute of Science in Rehovot, working under the institute’s director Shneior Lifson, who won the 1969 Israel Prize for his consistent force field method, one of the major theories behind systematic computer modeling of large molecules.
From 1969-72 Warshel performed post-doctoral work at Harvard in the US, where he worked with Karplus, an expert in quantum mechanics, to describe the structure and vibration of the retinal molecule. by using quantum and classical models, but without coupling them. He then returned to the Weizmann Institute and also worked at the Laboratory of Molecular Biology in Cambridge, England, where he was reunited with Levitt, a biophysicist he had met during his PhD. Together in 1976 they published the first computerized model combining the accuracy of quantum mechanics with the speed of molecular mechanics (QM/MM) of an enzymatic reaction, thus allowing for the study of chemical processes in solution and in proteins. The classical protein description used in that work was based on a computer program they had originally written as students in 1967.
Also in 1976, Warshel moved to the US to join the chemistry faculty at the University of Southern California in Los Angeles where he is now Distinguished Professor of Chemistry and Biochemistry and Dana and the David Dornsife Chair in Chemistry.. His interest in enzymes, which control almost all chemistry in the body, continues to this day, studying how proteins transfer signals within a cell.
By Volker Steger
This is not Schrödinger's cat! No realtion! But it's a quantum cat in a forest that looks more like classical physics. Blurr the forest and the cat stands out – just like with the big biomolecule on the right.
What a witty an charming man. And he's a gymnast, too...!