Time-resolved resonance Raman elucidation of the pathway for dioxygen reduction by cytochrome c oxidase
- Graduate Univ. of Advanced Studies, Okazaki (Japan)
- Himeji Inst. of Technology, Hyogo (Japan)
- Argonne National Lab., IL (United States)
Time-resolved resonance Raman (RR) spectra were observed for catalytic intermediates of bovine cytochrome c oxidase at room temperature by using an Artificial Cardiovascular System for Enzymatic Reactions and Raman/Absorption Simultaneous Measurement Device. The isotope-frequency-shift data using an asymmetrically labeled dioxygen, [sup 16]O[sup 18]O, established that the primary intermediate (compound A) is an end-on-type dioxygen adduct of cytochrome a[sub 3]. Higher resolution RR experiments revealed that the approximately 800-cm[sup [minus]1] band assigned previously to the Fe[sup TV]= O stretching mode of the subsequent intermediate (compound B) was actually composed of two bands that behaved differently upon deuteration. The 804/764-cm[sup [minus]1] pair for the [sup 16]O[sub 2]/[sup 18]O[sub 2] derivatives were insensitive to deuteration, and these bands became noticeably stronger at higher temperatures. The present experiments have conclusively established that the main pathway for dioxygen reduction by cytochrome c oxidase is Fe[sup II]-O[sub 2] [yields] Fe[sup III]-O-O-H [yields] Fe[sup IV]=O [yields] Fe[sup III]-OH and that their key bands for the [sup 16]O[sub 2]/[sup 18]O[sub 2] pair are at 571/544, 785/751, 804/764, and 450/425 cm[sup [minus]1], respectively. 79 refs., 8 figs., 3 tabs.
- DOE Contract Number:
- W-31109-ENG-38
- OSTI ID:
- 5115096
- Journal Information:
- Journal of the American Chemical Society; (United States), Journal Name: Journal of the American Chemical Society; (United States) Vol. 115:19; ISSN JACSAT; ISSN 0002-7863
- Country of Publication:
- United States
- Language:
- English
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400201* -- Chemical & Physicochemical Properties
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59 BASIC BIOLOGICAL SCIENCES
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
CYTOCHROME OXIDASE
ELEMENTS
ENZYMES
EVEN-EVEN NUCLEI
HAEM DEHYDROGENASES
ISOTOPES
KINETICS
LIGHT NUCLEI
NONMETALS
NUCLEI
ORGANIC COMPOUNDS
OXIDOREDUCTASES
OXYGEN
OXYGEN 16
OXYGEN 18
OXYGEN ISOTOPES
PROTEINS
RAMAN SPECTRA
REACTION KINETICS
REDUCTION
RESOLUTION
RESONANCE
RESPIRATORY SYSTEM
SPECTRA
STABLE ISOTOPES
TIME RESOLUTION
TIMING PROPERTIES