Open AccessThe cytochrome bd terminal oxidase of Azotobacter vinelandii : Low temperature photodissociation spectrophotometry reveals reactivity of cytochromes b 595 and d with both carbon monoxide and oxygen
Author(s) -
D'mello Rita,
Palmer Sarah,
Hill Susan,
Poole Robert K.
Publication year - 1994
Publication title -
fems microbiology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.899
H-Index - 151
eISSN - 1574-6968
pISSN - 0378-1097
DOI - 10.1111/j.1574-6968.1994.tb07084.x
Subject(s) - azotobacter vinelandii , cytochrome , chemistry , photochemistry , photodissociation , adduct , cytochrome c oxidase , hemeprotein , oxygen , heme , reactivity (psychology) , stereochemistry , biochemistry , enzyme , organic chemistry , nitrogenase , medicine , alternative medicine , pathology , nitrogen fixation , nitrogen
Cytochromes d and b 595 were studied by low temperature photodissociation 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 11 cytochrome b 595 . Oxy‐cytochrome d (648 nm) was formed when the CO adduct was photolysed in the presence of oxygen. This was followed by ligand recombination (presumably oxygen) to the high‐spin cytochrome b 595 , with a distinctive shift to shorter wavelengths of the α‐band of the cytochrome, and a decrease in the oxygenated form. All spectral changes were light‐reversible. We demonstrate the light‐reversible binding of CO to both cytochromes b 595 and d , and suggest migration of oxygen from cytochrome d to cytochrome b 595 at a haem‐haem binuclear centre during the oxidase reaction.