Mechanism of H[sub 2] metabolism on Fe-only hydrogenases.

The metabolism of hydrogen (H[SUB2]↔2H[SUP+]+2e[SUP-) constitutes a central process in the global biological energy cycle. Among all the enzymes that can mediate this process, Fe-only hydrogenases are unique in their particular high reactivity. Recently, some important progresses have been achieved. Following our previous paper [Z.-P. Liu and P. Hu, J. Am. Chem. Soc. 124, 5175 (2002)] that characterizes the individual redox state of the active site of Fe-only hydrogenase, in this work we have determined the feasible reaction pathways and energetics for the H[SUB2] metabolism on the active site of Fe-only hydrogenases, using density functional theory. We show that H[SUB2] metabolism possesses very low reaction barriers and a proximal base from a nearby protein plays an important role in H[SUB2] metabolism. [ABSTRACT FROM AUTHOR]