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. Author manuscript; available in PMC: 2020 Aug 20.
Published in final edited form as: Free Radic Biol Med. 2019 Feb 6;140:4–13. doi: 10.1016/j.freeradbiomed.2019.01.048

Figure 4. Dehydration by [4Fe-4S] clusters is elegant, but the enzymes are vulnerable to ROS.

Figure 4.

(A) The unique iron atom of the solvent-exposed cluster provides an electrostatic partner that activates substrate for deprotonation, and then it serves as a Lewis acid for dehydroxylation. (B) Hydrogen peroxide and superoxide (not shown) can bind and oxidize the cluster, destabilizing it. The steady-state cluster status in vivo represents the dynamic balance between oxidation and repair. The repair process (dotted line) has been observed but has not been genetically defined. The evolution of [2Fe-2S] and cluster-free dehydratases enables some enzymes to completely resist oxidation.