RESPIRATORY METABOLISM OF MITOCHONDRIA IN SOYBEAN ROOT NODULES

概要

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Bacteroid-free mitochondria exhibiting respiratory control were prepared from soybean root nodules using Percoll discontinuous gradient centrifugation. Though the activities of the enzymes for ethanol fermentation in the nodule cytosol fraction were higher than those in the root cytosol fraction, the mitochondria isolated from the nodules also displayed higher oxidative and phosphorylative activity of detached nodules and leghemoglobin content in the nodules varied nearly in parallel, increasing up to 6 weeks from sowing and then decreased. However, the amount of mitochondrial protein recovered from the nodules and the oxidative and phosphorylative activities in the nodule mitochondria hardly changed during the nodule development, except that the respiratory control ratio with malate as a substrate varied. The activities of the malic enzyme and isocitrate dehydrogenase in the nodule mitochondria were also constant throughout the development. Malate dehydrogenase and cytochrome c oxidase activities in the nodule mitochondria varied showing sharp peaks, without being closely correlated with the acetylene reducing activity. The mechanisms underlying the higher oxidative and phosphorylative activities of mitochondria in soybean root nodules were analyzed in relation to nitrogen fixation.
社団法人日本土壌肥料学会の論文