Volume 89 Issue 43 | p. 37 | Concentrates
Issue Date: October 24, 2011

Hydrogenase Spills Secret

Crystallography reveals novel cluster behind oxygen tolerance, opening up new possibilities for fuel-cell applications
Department: Science & Technology
News Channels: Materials SCENE
Keywords: hydrogenase, hydrogen, catalysis, enzyme, X-ray crystallography
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This [4Fe-3S] cluster is coordinated to six cysteine residues (white); Fe = orange, S = yellow.
Credit: Courtesy of Oliver Lenz
The [4Fe-3S] cluster in the hydrogenase enzyme of the microbe Ralstonia eutropha. Six cysteines (sticks) coordinate the cluster to the enzyme. Orange balls=iron, yellow balls=sulfur.
 
This [4Fe-3S] cluster is coordinated to six cysteine residues (white); Fe = orange, S = yellow.
Credit: Courtesy of Oliver Lenz

An enzyme that taps into hydrogen’s power with minimal interference from oxygen possesses a novel iron-sulfur cluster, according to two crystallography studies (Nature, DOI: 10.1038/nature10505 and 10.1038/nature10504). With nickel and iron clusters, hydrogenase enzymes split H2 into protons and electrons, but O2 squelches the activity of most hydrogenases. Some hydrogenases work in air, however, and potential applications such as H2-powered fuel cells or light-driven H2 production from water depend on uncovering the secret to those enzymes’ success. A German team led by Oliver Lenz of Humboldt University and Christian M. T. Spahn of Charité University Hospital, both in Berlin, and a Japanese team led by the University of Hyogo’s Yoshiki Higuchi each detected a cluster never before seen in an enzyme—four iron atoms and three sulfurs. These clusters typically have four iron and four sulfur atoms. The researchers propose that the distinctive cluster converts invading O2 to water by delivering electrons to the active site. Both studies showcase the versatility of iron-sulfur clusters, says Douglas C. Rees, who studies similar clusters at Caltech. “I would have loved to have done this work.”

 
Chemical & Engineering News
ISSN 0009-2347
Copyright © American Chemical Society

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