Unprecedented Fe(IV) Species in a Diheme Protein MauG: A Quantum Chemical Investigation on the Unusual Mossbauer Spectroscopic Properties

Yan Ling, University of Southern Mississippi
Yong Zhang, University of Southern Mississippi

Abstract

Ferryl species are important catalytic intermediates in heme enzymes. A recent experimental investigation of a diheme protein MauG reported the first case of using two Fe(IV) species as an alternative to compound I in catalysis. Both Fe(IV) species have unusual Mossbauer properties, which was found to originate from novel structural features based on a quantum chemical investigation. With comparison with the previously reported Fe(IV)=O and Fe(IV)-OH species, results here provide evidence of new mechanisms by which proteins influence the properties of ferryl species by directly providing the O via Tyr or stabilizing exogenous O via hydrogen bonding interaction. These results expand our ability to identify and evaluate high-valent heme proteins and models.