Selective resonance Raman observation of the ``607 nm`` form generated in the reaction of oxidized cytochrome c oxidase with hydrogen peroxide
- Okazaki National Research Institutes, Myodaiji, Okazaki (Japan)
- Himeji Inst. of Tech., Akogun, Hyogo (Japan). Dept. of Life Science
- Argonne National Lab., IL (United States). Chemistry Division
Resonance Raman spectra were measured selectively for the ``607 nm`` form, which had been assigned to a peroxy intermediate formed in the reaction of oxidized cytochrome c oxidase with hydrogen peroxide at ambient temperature. A single oxygen isotope-sensitive band was found at 803 cm{sup {minus}1} for the reaction with H{sub 2}{sup 16}O (at 769 cm{sup {minus}1} with H{sub 2}{sup 18}O{sub 2}) upon excitation at 6--7 nm, the wavelength of the difference absorption maximum characteristic of the ``peroxy`` intermediate. Upon excitation at shorter wavelengths (down to 5,480 nm), the Raman spectrum simply became weaker without yielding any new features. When H{sub 2}{sup 16}O{sup 18}O was used, two bands were observed at 803 and 769 cm{sup {minus}1} (within an accuracy of 0.5 cm{sup {minus}1}), but with only half the intensity of those observed with H{sub 2}{sup 16}O{sub 2} or H{sub 2}{sup 18}O{sub 2}, which ruled out the possibility that the 803 cm{sup {minus}1} band arose from the O-O or Fe-O{sub 2} stretching of the Fe{sup III}(O{sup {minus}}O{sup {minus}}) heme. Conversely, the 34-cm{sup {minus}1} downshift with {sup 18}O is in good agreement with the calculated {sup 16}O/{sup 18}O shift (35 cm{sup {minus}1}) expected for the diatomic Fe={sup 16}O oscillator at 803 cm{sup {minus}1}. This band exhibited an upshift by 1.3 cm{sup {minus}1} in {sup 2}H{sub 2}O, similar tot the case of compound II of horseradish peroxidase at neutral pH, and indicative of the presence of a hydrogen bond to the Fe{sup IV}=O oxygen. The 803/769 cm{sup {minus}1} pair of resonance Raman bands were also observed upon blue excitation, as is the case for the bands found in the dioxygen cycle of this enzyme.
- Research Organization:
- Argonne National Laboratory (ANL), Argonne, IL
- DOE Contract Number:
- W-31109-ENG-38
- OSTI ID:
- 136720
- Journal Information:
- Journal of Biological Chemistry, Journal Name: Journal of Biological Chemistry Journal Issue: 47 Vol. 269; ISSN JBCHA3; ISSN 0021-9258
- Country of Publication:
- United States
- Language:
- English
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