A better understanding of the role of oxygen in hydrogenases - which have applications in hydrogen gas production in fuel cells - is presented in a paper published online this week in Nature Chemical Biology.

NiFe hydrogenases can be used to convert protons to hydrogen gas or vice versa, and so can theoretically power fuel cells or similar environmentally-friendly processes. However, exposure to oxygen typically inactivates the enzymes. Prior work had led to a model where oxygen is incorporated as a ligand at the NiFe active site, trapping the active site until the oxygen could be removed.

Sebastien Dementin and colleagues now show that, while oxygen does interact with the active site - accepting an electron from the metals - it does not remain there. Additionally, other chemicals that can accept electrons can equally inhibit the enzyme. This changing model of hydrogenase function may allow researchers to better prevent this inactivation for future applications.