Chemical catalysts are essential in many transportation-related applications, including the treatment of engine emissions and the production of hydrogen.

Scientists at the U.S. Department of Energy’s Brookhaven National Laboratory have identified a bacterial enzyme with higher predicted chemical reactivity than that of industrial catalysts currently in use. The results of the team’s theoretical analysis will be published online by the Journal of Physical Chemistry B the week of January 24, 2005.

“We wanted to establish how the biological system works, and then compare it with materials currently used in industry for these chemical processes—and we found that the biological system is indeed better,” said Brookhaven chemist Jose Rodriguez, lead author of the paper. “The challenge now is whether we can reproduce this more efficient system for use in an industrial setting.” Added Brookhaven biochemist Isabel Abreu, the paper’s second author, “We are learning from nature what is working in nature, and then trying to use that for the design of other processes.”

The catalytic complex described is a particular configuration of iron and sulfur atoms and the surrounding amino acids in an enzyme isolated from Desulfovibrio desulfuricans, a bacterium that can live in sulfur-rich environments without oxygen. The specific chemical function of the iron-sulfur complex in this bacterial enzyme is not yet known, but similar complexes of iron and sulfur play an important role in many enzymes, catalysts, and sensors.

The scientists tested the theoretical chemical reactivity of the complex with a variety of reactants important in either the production of hydrogen or the control of air pollution. Finally, they compared those results with the reactivity of other iron-sulfur-complex catalysts, including those that are currently used for these catalytic processes in industry.

“Our calculations predict that this particular unit should be four to five times more reactive than the catalysts currently used, which is very significant,” Rodriguez said. “With this structure, the key is that you have an open side of the molecule to bind things and do chemistry because it is missing one cysteine neighbor — you can make it react with other things.”

The next challenge will be to see if the scientists can use the enzyme or synthesize a mimic of its cysteine-iron-sulfur center—an engineering project on the nanoscale (i.e., measured in billionths of a meter).

The research was funded by the Office of Basic Energy Sciences within the U.S. Department of Energy’s Office of Science. The CFN at Brookhaven Lab is one of five nanoscience research centers being constructed and funded by DOE’s Office of Science.