title: The pyruvate: ferredoxin oxidoreductase in heterocysts of the cyanobacterium Anabaena cylindrica.
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 oxidoreductase has been unambiguously demonstrated in extracts from heterocysts by the formation of acetylcoenzyme A, CO2 and reduced methyl viologen (ferredoxin) 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. alpha-Ketoglutarate: ferredoxin oxidoreductase is absent in Anabaena cylindrica, confirming that the organism has an incomplete tricarboxylic acid cycle.
mesh_terms: D002250:Carbon Radioisotopes; D000458:Cyanobacteria / Q000201:enzymology*; D006019:Glycolysis; D007658:Ketone Oxidoreductases / Q000378:metabolism*; D007700:Kinetics; D050743:Pyruvate Synthase; D011773:Pyruvates / Q000378:metabolism; D019289:Pyruvic Acid; D013172:Spores, Fungal / Q000201:enzymology*
chemical_list: D002250:Carbon Radioisotopes; D011773:Pyruvates; D019289:Pyruvic Acid; D007658:Ketone Oxidoreductases; D050743:Pyruvate Synthase