Resonance Raman study of cytochrome b562-o complex, a terminal oxidase of Escherichia coli in its ferric, ferrous, and CO-ligated states.
Cytochrome b562-o complex, a terminal oxidase in the respiratory chain of aerobically grown Escherichia coli, has been studied by resonance Raman spectroscopy in its air-oxidized, dithionite-reduced, and reduced and CO-ligated states. In the reduced state, with a 406.7-nm excitation, there appeared 1494 and 1473 cm-1 lines, indicating that low spin and high spin components are included in the cytochrome b562-o complex. For the air-oxidized protein, resonance Raman lines were observed at 1372, 1503, and 1580 cm-1 with a 413.1-nm excitation, indicating that there is a ferric low spin heme. In addition, a weak but appreciable Raman line was observed at 1480 cm-1 assignable to a ferric high spin heme. Accordingly, it was concluded that low spin and high spin components are included in the cytochrome b562-o complex in the reduced and the air-oxidized states. In the CO-ligated state, with a defocused laser beam of 413.1 nm, two Raman bands assignable to the Fe-CO stretching mode have been observed at 489 and 523 cm-1, as a major and a minor component, respectively. When the laser beam was focused upon the sample to cause a photodissociation of CO from the heme moiety, the intensity of the major band at 489 cm-1 was reduced as expected. On the other hand, the minor band at 523 cm-1 remained still obvious. It was suggested that the cytochrome b562-o complex may have an additional anomalous site for CO that is resistant to photodissociation.
Uno
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Nishimura
Y
Y
Tsuboi
M
M
Kita
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Anraku
Y
Y
D002248:Carbon Monoxide; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D003573:Cytochrome b Group / Q000378:metabolism*; D003576:Electron Transport Complex IV / Q000378:metabolism*; D004926:Escherichia coli / Q000201:enzymology*; D029968:Escherichia coli Proteins; D005290:Ferric Compounds; D005296:Ferrous Compounds; D007834:Lasers; D013059:Spectrum Analysis, Raman
D003573:Cytochrome b Group; D029968:Escherichia coli Proteins; D005290:Ferric Compounds; D005296:Ferrous Compounds; D002248:Carbon Monoxide; C017850:cytochrome b562, E coli; D003576:Electron Transport Complex IV