Active Site (IMAGE) Nara Institute of Science and Technology Caption Protons are transferred between the NiFe active site and protein surrounding through the Cyt546 and Glu34 residues during the catalytic reaction of [NiFe] hydrogenase. Credit Shun Hirota Usage Restrictions This image may be used only with appropriate credit. License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.