The oxygen reaction of the cytochrome d-terminated respiratory chain of Escherichia coli at sub-zero temperatures. Kinetic resolution by EPR spectroscopy of two high-spin cytochromes.
The oxygen reaction of the fully reduced respiratory chain in membranes from oxygen-limited Escherichia coli was studied at sub-zero temperatures using EPR spectroscopy. Laser photolysis of CO-liganded cytochrome oxidase d precedes oxidation of at least 2 kinetically separable high-spin cytochromes. At -120 to -100 degrees C, a rhombic signal appears, attributable to cytochrome d, followed at above -100 degrees C, by appearance of a second, axial signal near g = 6, here assigned to cytochrome(s) b, and changes in the redox state of iron-sulphur clusters. The data kinetically resolve the 2 high-spin signals attributed to the oxidase complex and suggest schemes for electron flow to oxygen.
D002462:Cell Membrane / Q000201:enzymology; D003080:Cold Temperature; D003573:Cytochrome b Group / Q000378:metabolism*; D017937:Cytochrome d Group; D003580:Cytochromes / Q000378:metabolism*; D004578:Electron Spin Resonance Spectroscopy; D004579:Electron Transport; D004926:Escherichia coli / Q000201:enzymology*; D007700:Kinetics
D003573:Cytochrome b Group; D003580:Cytochromes; D017937:Cytochrome d Group