Appearance of the. nu. (Fe sup IV double bond O) vibration from a ferryl-oxo intermediate in the cytochrome oxidase/dioxygen reaction
- Michigan State Univ., East Lansing (USA)
Time-resolved resonance Raman spectra have been recorded during the reaction of fully reduced (a{sup 2+}a{sub 3}{sup 2+}) cytochrome oxidase with dioxygen at room temperature. In the spectrum recorded at 800 {mu}s subsequent to carbon monoxide photolysis, a mode is observed at 790 cm{sup {minus}1} that shifts to 755 cm{sup {minus}1} when the experiment is repeated with {sup 18}O{sub 2}. The frequency of this vibration and the magnitude of the {sup 18}O{sub 2} isotopic frequency shift lead the authors to assign the 790-cm{sup {minus}1} mode to the Fe{sup IV}{double bond}O stretching vibration of a ferryl-oxo cytochrome a{sub 3} intermediate that occurs in the reaction of fully reduced cytochrome oxidase with dioxygen. The appearance and vibrational frequency of this mode were not affected when D{sub 2}O was used as a solvent. This result suggests that the ferryl-oxo intermediate is not hydrogen bonded. They have also recorded Raman spectra in the high-frequency region during the oxidase/O{sub 2} reaction that show that the oxidation of cytochrome a{sup 2+} is biphasic. These results on the kinetics of the redox activity of cytochrome a are consistent with the branched pathway discussed by Hill et al. for the oxidation of reduced cytochrome oxidase by O{sub 2} at room temperature.
- OSTI ID:
- 6098333
- Journal Information:
- Biochemistry; (USA), Vol. 29:32; ISSN 0006-2960
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
CYTOCHROME OXIDASE
RAMAN SPECTROSCOPY
REACTION INTERMEDIATES
BIOCHEMICAL REACTION KINETICS
CHEMICAL SHIFT
HEAVY WATER
OXIDATION
OXYGEN 18
VIBRATIONAL STATES
CHEMICAL REACTIONS
ENERGY LEVELS
ENZYMES
EVEN-EVEN NUCLEI
EXCITED STATES
HAEM DEHYDROGENASES
HYDROGEN COMPOUNDS
ISOTOPES
KINETICS
LASER SPECTROSCOPY
LIGHT NUCLEI
NUCLEI
OXIDOREDUCTASES
OXYGEN COMPOUNDS
OXYGEN ISOTOPES
REACTION KINETICS
SPECTROSCOPY
STABLE ISOTOPES
WATER
550601* - Medicine- Unsealed Radionuclides in Diagnostics