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Synthesis

Ronald Breslow Award For Achievement In Biomimetic Chemistry

Sponsored by the Ronald Breslow Award Endowment

by Rudy M. Baum
February 15, 2010 | A version of this story appeared in Volume 88, Issue 7

Lippard
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Credit: Courtesy of Stephen Lippard
Credit: Courtesy of Stephen Lippard

Research in Stephen J. Lippard’s lab at Massachusetts Institute of Technology encompasses several areas of bioinorganic chemistry involving different metals, and he has received his share of awards for the excellence of that work. This award, however, recognizes a particular one of Lippard’s long-standing passions: the study of nonheme iron proteins such as dioxygen-carrying hemerythrin and dioxygen-activating methane monooxygenase, an enzyme that Lippard describes as “an amazing biomolecular machine that converts methane and dioxygen selectively to methanol and water. It is the flagship of the fleet of multicomponent monooxygenases, like toluene/o-xylene monooxygenase, used in nature to oxidize hydrocarbons.”

Lippard’s involvement in biomimetic chemistry of carboxylate-bridged diiron proteins began in 1983 with the discovery of the first synthetic structural and spectroscopic model of hemerythrin. Although the compound did not display reversible oxygen binding, “over the years, Lippard and his coworkers’ relentless pursuit led to the synthesis of iron complexes that do indeed bind dioxygen,” says Boston College inorganic chemistry professor William H. Armstrong. “Lippard’s innovative ligand design has opened avenues to remarkable diiron complexes that display fascinating dioxygen chemistry, as well as varied substrate C–H bond oxidation catalysis, mimicking methane monooxygenase,” he continues.

As Lippard points out, studies with synthetic models focus on the use of sterically hindered carboxylate, macrocyclic, and preorganized ligands to afford complexes that best mimic the stoichiometric and functional properties of the enzyme active sites. “With the use of models, we now have carboxylate-bridged diiron systems with ligands that mimic those in the enzymes that can activate dioxygen and transfer oxygen atoms to hydrocarbon and other substrates,” he says.

“One feature that separates Lippard’s work from all others is that his group leads the way in studying the biomolecules he is mimicking,” Armstrong says. “It is not an exaggeration to say that he is the only scientist anywhere who is at the cutting edge in both the biochemistry and biomimetic chemistry of a class of metalloenzymes.” For example, Lippard’s lab has resolved structures of each of the components of methane monooxygenase and elucidated key details of how the enzyme converts methane to methanol.

Lippard earned a B.S. in chemistry from Haverford College in 1962 and a Ph.D. from MIT in 1965. He spent a year as a postdoctoral fellow at MIT and joined the faculty of Columbia University in 1966, becoming a full professor there in 1972. He returned to MIT in 1983 and served as chairman of the chemistry department from 1995 to 2005.

Lippard received the 2004 National Medal of Science in 2006, cited for “pioneering research in bioinorganic chemistry, including the interaction of metal compounds with DNA, preparation of synthetic models for metalloproteins, and structural and mechanistic studies of methane mono­ox­y­gen­ase.” He is a member of the National Academy of Sciences, the Institute of Medicine, and the American Academy of Arts & Sciences. He has received several ACS awards, including the Award in Inorganic Chemistry (1987), the Award for Distinguished Service in the Advancement of Inorganic Chemistry (1994), and the Alfred Bader Award in Bioinorganic or Bioorganic Chemistry (2004).

“One thing that shouldn’t be lost is that Ron Breslow was my colleague at Columbia for many years, and it is a distinct privilege to receive an award bearing his name,” Lippard tells C&EN.

Lippard will present the award address before the Division of Inorganic Chemistry.

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