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In this issue:
Scientists Probe the Mechanism for Microbial Carbon Fixation
Colloquium Next Week: Congressman Bill Foster

SLAC Today

Monday - September 20, 2010

Scientists Probe the Mechanism for Microbial Carbon Fixation

Image of the CODH enzyme's active site, with (a) and without (b) a sulfide bridge important to its function. (Image courtesy the researchers.)

Even the smallest organisms can help address the problem of increasing pollutants and greenhouse gases in the Earth's atmosphere. Each year, some microorganisms using the enzyme carbon monoxide dehydrogenase, or CODH, take an estimated 100 million tons of carbon monoxide from our air, while others use CODH to produce 10 billion tons of acetate from carbon dioxide.

CODH catalyzes the reversible reaction of carbon monoxide to CO2, which different types of bacteria use in creating the molecules they need to live. The enzyme has a complicated metal cluster, the C-cluster, which includes nickel, iron and sulfur ions in its active site, that performs this unusual chemistry. Understanding how this catalysis works may provide insights to chemical engineers wanting to duplicate this chemical process as a solution to the buildup of greenhouse gases in the atmosphere.

A team of scientists led by Catherine Drennan of MIT used the Stanford Synchrotron Radiation Lightsource Beamline 11-1 and a beamline at Lawrence Berkeley National Laboratory's Advanced Light Source to decipher the mechanism of CODH's reaction. They deciphered crystal structures of the C-cluster bound to its target and a molecule that inhibits its action. Analyzing the structures, they were able to deduce the roles of the bound metals and the mechanism of the reaction.

This clearer understanding of how this microbial enzyme performs its difficult chemistry could lead to methods of controlling pollutants and greenhouse gases in our atmosphere. This work was published in the journal Biochemistry.

To learn more about this research see the full scientific highlight.

Colloquium Next Week:
Congressman Bill Foster

(Image - SLAC Colloquium banner)

This year's Monday SLAC colloquium series begins with a talk from physicist and U.S. Representative Bill Foster. After a 25 year career in high-energy and accelerator physics, Bill Foster ran for Congress for the Illinois 14th district in 2008, and has twice been elected to represent this diverse district. Next Monday afternoon Foster will highlight some of his successes and frustrations in Congress, and offer his suggestions on how scientists can help shape good policy and how their skills can be applied to national opportunities and challenges. The title of Foster's talk is "Another kind of Many-Body Problem—Experiences of a Physicist in the United States Congress."

Foster received his bachelor's degree in physics from the University of Wisconsin-Madison in 1975 and his Ph.D. in physics from Harvard University in 1983. He has been elected a fellow of the American Physical Society, received the Rossi Prize for Cosmic Ray Physics for the discovery of the neutrino burst from Supernova SN1987a, received the Particle Accelerator Technology Prize from the Institute of Electrical and Electronic Engineers, and was awarded an Energy Conservation award from the U.S. Department of Energy for his invention and application of permanent magnets for Fermilab’s accelerators. He is currently serving in his second term of office. In a nationally watched race, Representative Foster won a special election in March 2008 to complete the term of former Republican Speaker of the House Dennis Hastert. In addition to being a bellwether for races to come, this win earned him the distinction of being the first Democrat to represent the 14th District since the 1970s. Foster followed up his March victory with another 16-point win in November 2008, and was sworn-in on January 3, 2009.

Refreshments will begin at 3:45 p.m. next Monday, September 27. Foster's talk will start at 4:15 p.m. in Panofsky Auditorium. The colloquium is free and open to all.


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