Nitrite Formation at a Diiron Dinitrosyl Complex.

Pathogenic bacteria employ iron-containing enzymes to detoxify nitric oxide (NO) produced by mammals as part of their immune response. Two classes of diiron proteins, flavodiiron nitric oxide reductases (FNORs) and the hemerythrin-like proteins from mycobacteria (HLPs), are upregulated in bacteria in response to an increased local NO concentration. While FNORs reduce NO to nitrous oxide (NO), the HLPs have been found to either reduce nitrite to NO (YtfE), or oxidize NO to nitrite (-HLP).

Site-Differentiated MnFe Complex Reproducing the Selective Assembly of Biological Heterobimetallic Mn/Fe Cofactors.

Class Ic ribonucleotide reductases (RNRIc) and R2-like ligand-binding oxidases (R2lox) are known to contain heterobimetallic MnFe cofactors. How these enzymes assemble MnFe cofactors has been a long-standing puzzle due to the weaker binding affinity of Mn versus Fe. In addition, the heterobimetallic selectivity of RNRIc and R2lox has yet to be reproduced with coordination complexes, leading to the hypothesis that RNRIc and R2lox overcome the thermodynamic preference for coordination of Fe over Mn with their carefully constructed three-dimensional protein structures.

Iron(II/III) Halide Complexes Promote the Interconversion of Nitric Oxide and -Nitrosothiols through Reversible Fe-S Interaction.

Heme and non-heme iron in biology mediate the storage/release of NO from -nitrosothiols as a means to control the biological concentration of NO. Despite their importance in many physiological processes, the mechanisms of N-S bond formation/cleavage at Fe centers have been controversial. Herein, we report the interconversion of NO and -nitrosothiols mediated by Fe/Fe chloride complexes.