Respiration of the hydrogenosome-containing fungus Neocallimastix patriciarum |
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| Authors: | N. Yarlett C. Rowlands J. C. Evans D. Lloyd |
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| Affiliation: | (1) Department of Microbiology, University College, Newport Road, CF2 1TA Cardiff, UK;(2) Present address: Haskins Laboratories of Pace University, 41 Park Row, 10038 New York, NY, USA;(3) Department of Chemistry, University College, Newport Road, CF2 1TA Cardiff, UK;(4) The Rockefeller University, 1230 York Avenue, 10021 New York, NY, USA |
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| Abstract: | Mass spectrometric determinations of O2 affinities by the rumen fungus Neocallimastix patriciarum indicated a stable respiration under liquid phase O2 concentrations up to 10  M, the apparent Km for O2 under these conditions was 4.0 M. Exposure to O2 concentrations in excess of 10 M resulted in rapid inactivation of the observed respiration. Calculated H2 evolution rates for the organism are 8.1 nmol min-1 per mg of protein. Exposure to liquid-phase O2 concentrations in excess of 1.4 M caused 50% inhibition of H2 production. That superoxide and peroxide are amongst the products of respiration was shown by the use of ESR spectroscopy with the spin trapping agent 5,5-dimethyl-l-pyrroline-N-oxide. An active superoxide dismutase was present, but catalase could not be detected.Abbreviations ESR electron spin resonance - DMPO 5,5-dimethyl-l-pyrroline-N-oxide - DETAPAC diethylene-triamine pentaacetic acid |
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| Keywords: | Oxygen affinity Anaerobiosis Superoxide Rumen fungus Hydrogen production |
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