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Spectroscopic evidence for the presence of a high‐valent Fe( IV ) species in the ferroxidase reaction of an archaeal ferritin
Author(s) -
Honarmand Ebrahimi Kourosh,
Bill Eckhard,
Hagedoorn PeterLeon,
Hagen Wilfred R.
Publication year - 2017
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1002/1873-3468.12697
Subject(s) - ceruloplasmin , chemistry , ferritin , biochemistry
A high‐valent Fe( IV ) species is proposed to be generated from the decay of a peroxodiferric intermediate in the catalytic cycle at the di‐iron cofactor center of dioxygen‐activating enzymes such as methane monooxygenase. However, it is believed that this intermediate is not formed in the di‐iron substrate site of ferritin, where oxidation of Fe( II ) substrate to Fe(III) (the ferroxidase reaction) occurs also via a peroxodiferric intermediate. In opposition to this generally accepted view, here we present evidence for the occurrence of a high‐valent Fe( IV ) in the ferroxidase reaction of an archaeal ferritin, which is based on trapped intermediates obtained with the freeze‐quench technique and combination of spectroscopic characterization. We hypothesize that a Fe( IV ) intermediate catalyzes oxidation of excess Fe( II ) nearby the ferroxidase center.