Sponsored by the ACS Northeastern Section
Free radicals are a big concern for our cells. The cells constantly bump into molecular oxygen, which, through radical reactions, oxidizes organic molecules in the cells. Many of these oxidized compounds are toxic and can trigger cells to die.
Ned A. Porter of Vanderbilt University has spent his career studying radical reactions, including some that are responsible for oxidation inside human cells. This award recognizes, in part, his work on the mechanisms of these biologically important reactions.
“Ned has been at the forefront of the physical chemistry of radical reactions throughout his career,” says physical organic chemist Martin E. Newcomb of the University of Illinois, Chicago.
One area of Porter’s research has focused on radical reactions involved in oxidation of lipids. These greasy molecules serve as signaling molecules in cells or as components of cell membranes. For example, he’s recently investigated the oxidation of a sterol called 7-dehydrocholesterol and connected it to Smith-Lemli-Opitz syndrome, a rare developmental disorder. The disease causes parts of the body to form improperly, particularly in the nervous system.
The origin of this project was pure physical organic chemistry. “We got into this research because of a rate constant,” Porter explains. He and his research group had been working with the sterol, which is a precursor to cholesterol in our cells, and found that it was the most readily oxidized molecule they’d ever encountered. Porter started reading about the compound and found that people with the syndrome have elevated levels of the sterol, because they inherit a mutation that disrupts an enzyme that converts the compound to cholesterol.
Porter’s group has identified toxic products of the sterol’s oxidation. They’ve also searched for and found several of these compounds in patients’ blood and in mouse models of the syndrome. Porter thinks that when an affected fetus starts to produce its own cholesterol, which is normally incorporated in the protective sheath around nerve cells, it accumulates this sterol instead, which then is oxidized to produce high levels of toxic compounds.
Besides this lipid oxidation work, Porter also has made significant contributions involving the use of radicals in organic synthesis. He showed that tools such as chiral auxiliaries and chiral Lewis acids that are used to dictate the stereochemical outcomes in nonradical reactions also work with radical reactions. As a result of this work, there has been a boom in the use of radicals in enantioselective syntheses, says organic chemist Dennis P. Curran of the University of Pittsburgh.
Porter says the award humbles him: “When I look at the list of others who have won this award,” he notes, “many of them were heroes of mine when I was a graduate student and throughout my career.”
Porter, 69, received a B.S. in chemistry and chemical engineering from Princeton University in 1965 and a Ph.D. in organic chemistry from Harvard University in 1970. He then joined the chemistry faculty at Duke University, becoming a full professor in 1979. Porter moved to Vanderbilt in 1998. He was the chemistry department chair from 2003 to 2009 and became a biochemistry professor in 2003.
Porter will present the award address before the ACS Division of Organic Chemistry.