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Indian Journal of Chemistry -Section A (IJC-A) >
IJC-A Vol.50A [2011] >
IJC-A Vol.50A(03-04) [March-April 2011] >
| Title: | Probing dioxygen activation mechanisms in heme-containing enzymes by heme models |
| Authors: | Liu, Jin-Gang
Naruta, Yoshinori |
| Keywords: | Bioinorganic chemistry
Cytochrome c oxidase
Heme proteins
Enzyme models
Dioxygen activation |
| Issue Date: | Mar-2011 |
| Publisher: | NISCAIR-CSIR, India |
| Abstract: | In this mini-review, we summarize our
recent synthetic model studies on the mechanism of dioxygen reduction reaction
involved in cytochrome c oxidase (CcO), as well as on the dioxygen binding and activation associated with
general heme-containing enzymes. A series of heme/copper
dinuclear complexes bearing a cross-linked His-Tyr mimic have been designed and
synthesized as synthetic models of the active site of CcO, focusing on the possible role(s) of the cross-linked His-Tyr-CuB
moiety. The spectroscopic evidences from the oxygenation reaction of these
model compounds demonstrate that the role(s) of the cross-linked His-Tyr
moiety is more likely to be structural and a proton mediator rather than acting
as the fourth electron donor in the dioxygen
reduction process. It also implies that after
one-electron reduction of the oxyheme unit in CcO under physiological conditions, O-O bond cleavage could
occur through a FeIII-OOH rather than a peroxo
FeIII-(O22-)-CuII
species. In addition, as key intermediates involved in the catalytic cycles
of heme-containing enzymes, the low-spin end-on ferric-peroxo
and ferric-hydroperoxo intermediates have been successfully captured and spectroscopically
characterized in solution for the first time by using of delicate designed heme
models. The results suggest the crucial role of the axial imidazole
ligation to heme for O2 activation |
| Page(s): | 363-373 |
| CC License: |  CC Attribution-Noncommercial-No Derivative Works 2.5 India |
| ISSN: | 0975-0975(Online); 0376-4710(Print) |
| Source: | IJC-A Vol.50A(03-04) [March-April 2011]
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