title: Localization and characterization of cytochromes from membrane vesicles of Escherichia coli K-12 grown in anaerobiosis with nitrate.
abstract: Cytochromes b of anaerobically nitrate-grown Escherichia coli cells are analysed. Ascorbate phenazine methosulfate distinguishes low and high potential cytochromes b. Reduction kinetics performed at 559 nm presents a very complex pattern which can be analysed assuming that at least four b-type cytochromes are present. The electron transport chain from formate to oxygen would contain a low potential cytochrome b-556, a cytochrome b-558 associated to the oxidase, and a cytochrome d as the principle oxidase. Cytochrome o is also present, but seems to be functional only at low oxygen concentrations. A cytochrome b-556 associated to nitrate reductase is shown to belong to a branch of the formate-oxidase chain. 2-N-Heptyl-4-hydroxyquinoline-N-oxide affects the reduction kinetics in a very complex way. One inhibition site is in evidence between cytochrome b-558 and cytochrome d; another between the cytochrome associated to nitrate reductase and the nitrate reductase. A third inhibition site is located in the common part of the formate-nitrate and the formate-oxidase systems. Ascorbate phenazine methosulfate is shown to donate electrons near cytochrome b-558.
mesh_terms: D000693:Anaerobiosis; D002248:Carbon Monoxide; D002462:Cell Membrane / Q000378:metabolism; D003580:Cytochromes / Q000302:isolation & purification / Q000378:metabolism*; D004926:Escherichia coli / Q000187:drug effects / Q000378:metabolism*; D007700:Kinetics; D009566:Nitrates / Q000494:pharmacology*; D010084:Oxidation-Reduction; D013053:Spectrophotometry
chemical_list: D003580:Cytochromes; D009566:Nitrates; D002248:Carbon Monoxide