Credit: Image courtesy of Pacific Northwest National Laboratory (Nathan Johnson)
nteractions between the rings on the amino acid phenylalanine (on the tablet) alter the nickel (Ni) active site, while the COOH groups provide proton relays in blue. The relays create a proton path from the active site to the outside of the molecule. On the computer screen, see PNNL’s molecule (left) and the enzyme [FeFe]-hydrogenase. Both have proton paths with similar features, vital for reversibly producing and breaking hydrogen