ferryl-iron and ferric-hydroxide

The protonation state of ascorbate peroxidase compound II (APX-II) has been a subject of debate. A combined X-ray/neutron crystallographic study reported that APX-II is best described as an iron(IV)hydroxide species with an FeO distance of 1.88 Å (Kwon, et al. Nat Commun2016, 7, 13,445), while X-ray absorption spectroscopy (XAS) experiments (utilizing extended X-ray absorption fine structure (EXAFS) and pre-edge analyses) indicate APX-II is an authentic iron(IV)oxo species with an FeO distance 1.68 Å (Ledray, et al. Journal of the American Chemical Society2020,142, 20,419). Previous debates concerning ferryl protonation states have been resolved through the application of Badger's rule, which correlates FeO bond distances with FeO vibrational frequencies. To obtain the required vibrational data, we have collected Nuclear Resonance Vibrational Spectroscopy (NRVS) data for APX-II. We observe a broad vibrational feature in the range associated with iron(IV)oxo stretching (700-800 cm

Topics: Ascorbate Peroxidases; Crystallography, X-Ray; Ferric Compounds; Hydrogen Bonding; Hydroxides; Iron; Magnetic Resonance Spectroscopy; Molecular Structure; Oxygen; Protons; Spectrum Analysis, Raman; X-Ray Absorption Spectroscopy