ferredoxin

In cells, it requires several enzymes that send the electrons uphill to an ancient and essential biological electron carrier called ferredoxin.

The new study shows that at pH 8.5, typical of naturally alkaline vents, "no proteins are required," explains Buckel, co-author on the study, "the H-H bond of H2 splits on the iron surface, generating protons that are consumed by the alkaline water and electrons that are then easily transferred directly to ferredoxin."

"Several different theories have proposed how the environment might have pushed electrons energetically uphill to ferredoxin before the origin of electron bifurcation," says Martin, "we have identified a process that could not be simpler and that works in the natural conditions of hydrothermal vents."

Iron was the only metal identified in the new study that was able to send the electrons in H2 uphill to ferredoxin.

In natural systems, FNR accepts two electrons from a protein partner called ferredoxin.