The pyruvate: Ferredoxin oxidoreductase in heterocysts of the cyanobacteriuim Anabaena cylindrica |
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Authors: | Gabriele Neuer Hermann Bothe |
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Institution: | Botanisches, Institut, Universität Köln, Gyrhofstr. 15, 5 Köln 41, F.R.G. |
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Abstract: | Heterocyst preparations have been obtained which actively perform nitrogen fixation (C2H2 reduction) and contain the enzymes of glycolysis and some of the tricarboxylic acid cycle. Pyruvate: ferredoxin oxidereductase has been unambiguously demonstrated in extracts from heterocysts by the formation of acetylcoenzyme A, CO2 and reduced methyl viologen (ferredoxi) from pyruvate, coenzyme A and oxidized methyl viologen (ferredoxin) as well as by the synthesis of pyruvate from CO2, acetylcoenzyme A and reduced methyl viologen. Pyruvate supports C2H2 reduction by isolated heterocysts, however, with lower activity than Na2S2O4 and H2. α-Ketoglutarate: ferredoxin oxidoreductase is absent in Anabaena cylindrica, confirming that the organism has an incomplete tricarboxylic acid cycle. |
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Keywords: | Pyruvate: ferredoxin oxidoreductase Nitrogen fixation (A cylindrica heterocysts) Hepes 4-(2-hydroxyethyl)-1-piperazineethane-sulphonic acid |
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