The oxo/peroxo debate: a nonheme iron perspective

Area of Science:

• Biochemistry
• Inorganic Chemistry
• Enzymology

Background:

• Nonheme iron enzymes share similarities with heme enzymes in oxygen activation mechanisms.
• Both systems are proposed to involve iron-peroxo and iron-oxo species in catalytic cycles.
• Nonheme ligand environments offer greater flexibility in dioxygen coordination and activation compared to heme systems.

Purpose of the Study:

• To summarize and discuss the evidence for iron-peroxo and iron-oxo intermediates in nonheme iron systems.
• To compare the dioxygen activation mechanisms in nonheme iron systems with those in heme enzymes.
• To contribute to the ongoing discussion regarding the nature of oxidants in heme enzymes.

Main Methods:

• Literature review and synthesis of existing evidence.
• Comparative analysis of nonheme and heme iron catalytic mechanisms.
• Discussion of spectroscopic and mechanistic data related to iron-oxygen intermediates.

Main Results:

• Nonheme iron systems exhibit diverse dioxygen activation modes due to flexible ligand environments.
• Evidence supports the involvement of iron-peroxo and iron-oxo species in nonheme iron catalysis.
• Comparison with heme enzymes highlights both conserved and distinct features in oxygen activation.

Conclusions:

• The flexibility of nonheme ligand environments leads to varied dioxygen activation strategies.
• Iron-peroxo and iron-oxo intermediates are key species in nonheme iron catalytic cycles.
• Understanding nonheme iron mechanisms provides insights into the broader field of oxygen activation in enzymes.