10.1021/bi0609218.s001
Jennifer Belyea
Jennifer
Belyea
Curtis M. Belyea
Curtis M.
Belyea
Simon Lappi
Simon
Lappi
Stefan Franzen
Stefan
Franzen
Resonance Raman Study of Ferric Heme Adducts of Dehaloperoxidase from
<i>Amphitrite ornata</i><sup>†</sup>
American Chemical Society
2006
ferric heme iron
electron donor ability
HRP
resonance Raman spectroscopy
OH
Raman data support
SCN
heme iron
core size marker modes
ligand series X
DHP
HHMb
horse heart myoglobin
Ferric Heme Adducts
CN
Resonance Raman Study
peroxidase
terebellid polychaete Amphitrite ornata
2006-12-05 00:00:00
Journal contribution
https://acs.figshare.com/articles/journal_contribution/Resonance_Raman_Study_of_Ferric_Heme_Adducts_of_Dehaloperoxidase_from_i_Amphitrite_ornata_i_sup_sup_/3043597
The study of axial ligation by anionic ligands to ferric heme iron by resonance Raman
spectroscopy provides a basis for comparison of the intrinsic electron donor ability of the proximal histidine
in horse heart myoglobin (HHMb), dehaloperoxidase (DHP), and horseradish peroxidase (HRP). DHP is
a dimeric hemoglobin (Hb) originally isolated from the terebellid polychaete <i>Amphitrite ornata</i>. The
monomers are structurally related to Mb and yet DHP has a peroxidase function. The core size marker
modes, ν<sub>2</sub> and ν<sub>3</sub>, were observed using Soret excitation, and DHP-X was compared to HHMb-X for the
ligand series X = F, Cl, Br, SCN, OH, N<sub>3</sub>, and CN. Special attention was paid to the hydroxide adduct,
which is also formed during the catalytic cycle of peroxidases. The Fe−OH stretching frequency was
observed and confirmed by deuteration and is higher in DHP than in HHMb. The population of high-spin
states of the heme iron in DHP was determined to be intermediate between HHMb and HRP. The data
provide the first direct measurement of the effect of axial ligation on the heme iron in DHP. The Raman
data support a modified charge relay in DHP, in which a strongly hydrogen-bonded backbone carbonyl
(>CO) polarizes the proximal histidine. The charge relay mechanism by backbone carbonyl >CO-His-Fe is the analogue of the Asp-His-Fe of peroxidases and Glu-His-Fe of flavohemoglobins.