Mechanism of strong resistance of Helicobacter pylori respiration to nitric oxide |
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Authors: | Park Ah-Mee Nagata Kumiko Sato Eisuke F Tamura Toshihide Shimono Kunio Inoue Masayasu |
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Affiliation: | Department of Biochemistry and Molecular Pathology, Osaka City University Medical School, 1-4-3 Asahimachi, Abeno, 545-8585, Osaka, Japan. |
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Abstract: | The aim of the present work is to elucidate the mechanism by which the respiration of Helicobacter pylori but not of Escherichia coli shows a strong resistance to nitric oxide (NO). Nitric oxide strongly but reversibly inhibited the oxygen consumption by sonicated membranes from H. pylori and Triton X-100-treated cells. Although the sensitivity of the H. pylori respiration to cyanide was low, it also increased after the treatment with Triton X-100. Kinetic analyses revealed that NO was rapidly degraded by E. coli and the Triton X-100-treated H. pylori, but not by the intact H. pylori. Thus, the low sensitivity to NO might reflect the low affinity of the cytochrome c oxidase for this radical within the membrane/lipid bilayers of H. pylori. Such properties of the oxidase in H. pylori membranes may, at least in part, underlie the mechanism by which this bacterium thrives in NO-enriched gastric juice. |
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Keywords: | Helicobacter pylori Respiration Nitric oxide Cytochrome c oxidase Oxidative stress Superoxide Mitochondria Gastric ulcer |
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