Ferric Heme Superoxide Reductive Transformations to Ferric Heme (Hydro)Peroxide Species: Spectroscopic Characterization and Thermodynamic Implications for H-Atom Transfer (HAT).

ABSTRACT: A new end-on low-spin ferric heme peroxide, [(P^Im )Fe^III -(O₂ ^2- )]^- (P^Im -P), and subsequently formed hydroperoxide species, [(P^Im )Fe^III -(OOH)] (P^Im -HP) are generated utilizing the iron-porphyrinate P^Im with its tethered axial base imidazolyl group. Measured thermodynamic parameters, the ferric heme superoxide [(P^Im )Fe^III -(O₂ ^⋅- )] (P^Im -S) reduction potential (E°') and the P^Im -HP pK_a value, lead to the finding of the OO-H bond-dissociation free energy (BDFE) of P^Im -HP as 69.5 kcal mol^-1 using a thermodynamic square scheme and Bordwell relationship. The results are validated b

SUBMITTER: Kim H 

PROVIDER: S-EPMC7920932 | biostudies-literature | 2021 Mar

REPOSITORIES: biostudies-literature