New Iron–Sulfur Clusters Help Hydrogenases Tolerate Oxygen

One S less : Recent crystallographic studies have revealed a new, oxygen‐tolerant kind of iron–sulfide cluster [4Fe‐3S], which contains only three rather than four sulfur atoms in its cage (see picture; yellow=S, red=Fe, blue=N, green=cysteine). It is proposed that the cluster's ability to transfer multiple electrons increases the oxygen tolerance by enabling the enzyme to reduce O 2 rapidly, converting the dioxygen into harmless water before it can damage the protein.