THE CYTOCHROME-BD TERMINAL OXIDASE OF AZOTOBACTER-VINELANDII - LOW-TEMPERATURE PHOTODISSOCIATION SPECTROPHOTOMETRY REVEALS REACTIVITY OF CYTOCHROMES-B(595) AND CYTOCHROME-D WITH BOTH CARBON-MONOXIDE AND OXYGEN
R. Dmello et al., THE CYTOCHROME-BD TERMINAL OXIDASE OF AZOTOBACTER-VINELANDII - LOW-TEMPERATURE PHOTODISSOCIATION SPECTROPHOTOMETRY REVEALS REACTIVITY OF CYTOCHROMES-B(595) AND CYTOCHROME-D WITH BOTH CARBON-MONOXIDE AND OXYGEN, FEMS microbiology letters, 121(1), 1994, pp. 115-120
Cytochromes d and b(595) were studied by low temperature photodissocia
tion of CO-ligated Azotobacter vinelandii membranes. White light or He
-Ne laser irradiation revealed 436 and 594-597 nm absorption bands to
be due to Fe-II cytochrome b(595). Oxy-cytochrome d (648 nm) was forme
d when the CO adduct was photolysed in the presence of oxygen. This wa
s followed by ligand recombination (presumably oxygen) to the high-spi
n cytochrome b(595), With a distinctive shift to shorter wavelengths o
f the alpha-band of the cytochrome, and a decrease in the oxygenated f
orm. All spectral changes were light-reversible. We demonstrate the li
ght-reversible binding of CO to both cytochromes b(595) and d, and sug
gest migration of oxygen from cytochrome d to cytochrome b595 at a hae
m-haem binuclear centre during the oxidase reaction.