Following Nature's Lead,
Scientists Seek Better Catalysts
Theoretical investigations of a bacterial enzyme by
Brookhaven Lab scientists have revealed a catalytic complex with higher
predicted chemical reactivity than that of industrial catalysts
currently in use. This research sparks hope for cleaner, more efficient
-- by Karen McNulty Walsh
Theoretical investigations of a bacterial enzyme by Brookhaven Lab scientists have revealed a catalytic complex with higher predicted chemical reactivity than that of industrial catalysts currently in use, sparking hope for cleaner, more efficient hydrogen production.
“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. “The challenge now is whether we can reproduce this more efficient system for use in an industrial setting.”
Added former Brookhaven biochemist Isabel Abreu, “We are learning from nature what is working in nature, and then trying to use that for the design of other processes.”
The complex studied 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.
Earlier studies by Abreu and coworkers suggested that, unlike iron-sulfur complexes found in other proteins, which are usually bound to four surrounding cysteine amino acids, the iron-sulfur complex from D. desulfuricans appeared to have only three bound cysteine neighbors.
“This opened up the possibility of interesting chemical properties,” Abreu said.
Rodriguez and Abreu’s first step was to use “density functional calculations” to establish if a structural model previously proposed by Abreu for the three-cysteine configuration was theoretically stable enough to exist in nature, and then to investigate how that structure might influence the reactivity of the iron-sulfur complex. In agreement with the predicted model, they found that the three-cysteine structure was indeed stable, leaving the iron-sulfur complex — located in a surface pocket of the bacterial enzyme — exposed on one side.