Theoretical chemist Martin Karplus dies at 94

Martin Karplus, professor of chemistry emeritus at Harvard University and professeur conventionné at the University of Strasbourg, died Dec. 28 at the age of 94.

Born in Vienna in 1930, Karplus would often tell the story of how his eighth birthday party was ruined when his family fled Nazi Germany’s invasion of Austria, says Bernard Brooks, a past postdoctoral fellow in Karplus’s group.

The family immigrated to the US and settled in the Boston area. A childhood gift of a microscope set Karplus on a path to studying biology and chemistry as an undergraduate at Harvard, where he received a BA in 1950.

Karplus began graduate work in biology at the California Institute of Technology on advice from J. Robert Oppenheimer. But Karplus’s adviser criticized his first seminar so severely that Karplus left biology for Linus Pauling’s group in the chemistry department. He completed his PhD in 1953.

After finishing his postdoctoral work at the University of Oxford, Karplus joined the chemistry faculty at the University of Illinois. There he derived the Karplus Equation, which relates nuclear magnetic resonance coupling constants and molecular bond angles. He then moved to Columbia University, where he researched reaction kinetics, before returning to Harvard in 1966.

At Harvard, Karplus developed models for molecular dynamics simulations. In 1983, he coauthored the paper introducing the Chemistry at Harvard Macromolecular Mechanics (CHARMM), a collection of computer programs using classical mechanics to predict molecular motion. It’s still in wide use today. “The CHARMM community has been extraordinarily stable,” says Brooks, who was the paper’s first author. That’s largely because “Martin did an extraordinarily good job of keeping it together,” he adds.

In 2013, Karplus shared the Nobel Prize in Chemistry with Arieh Warshel of the University of Southern California and Michael Levitt of the Stanford University School of Medicine. The award recognized the three for “the development of multiscale models for complex chemical systems,” specifically programs they developed in the 1970s.

“If you like to know how a machine works, you take it apart,” Karplus told the Harvard Gazette after winning the prize. “We do that for molecules.”

Warshel writes in an email to C&EN that Karplus “had a great energy, ambition and influence that helped him to make our field of multiscale modeling a major part of modern chemistry and biology.” Karplus will likely be remembered for promoting the idea that dynamics plays a major role in biology, he adds.

Karplus was also “a real Renaissance man,” Levitt says. “Besides being a really good theoretical chemist, he was also an extremely good cook and gourmand, and also a really, really good photographer.”