The respiratory chain of Helicobacter pylori: identification of cytochromes and the effects of oxygen on cytochrome and menaquinone levels |
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Authors: | Simon W Marcelli Huai-tzu Chang Trevor Chapman Peter A Chalk roger J Miles Robert K Poole |
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Institution: | Division of Life Sciences, King's College London, Kensington Campus, Campden Hill Road, London W8 7AH, UK; Glaxo Wellcome Medicines Research Centre, Gunnels Wood Road, Stevenage, Herts SG1 2NY, UK |
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Abstract: | Abstract The quinone and cytochrome components of the respiratory chain of the microaerophilic bacterium Helicobacter pylori have been investigated. The major isoprenoid quinone was menaquinone-6, with traces of menaquinone-4; no methyl-substituted or unusual menaquinone species were found. Cell yield was highest after growth at 10% (v/v) oxygen and menaquinone levels (per dry cell mass) were maximal at 5–10% (v/v) oxygen. Helicobacter pylori cells and membranes contained b -and c -type cytochromes, but not terminal oxidases of the a -or d -types, as judged by reduced minus oxidised difference spectra. Spectra consistent with the presence of a CO-binding terminal oxidase of the cytochrome b -or o -type were obtained. The soluble fraction from disrupted cells also contained cytochrome c . There were no significant qualitative differences in the cytochrome complements of cells grown at oxygen concentrations in the range 2–15% (v/v) but putative oxidases were highest in cells grown at 5–10% (v/v) oxygen. |
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Keywords: | Cytochrome Helicobacter pylori Menaquinone Microaerophily Oxygen metabolism Respiration Oxidases |
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