Open AccessDifferent functions assigned to NAD(H) and NADP(H) in light‐dependent nitrogen fixation by heterocysts of Anabaena variabilis
Author(s) -
Schrautemeier Bernhard,
Böhme Herbert
Publication year - 1984
Publication title -
fems microbiology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.899
H-Index - 151
eISSN - 1574-6968
pISSN - 0378-1097
DOI - 10.1111/j.1574-6968.1984.tb01459.x
Subject(s) - heterocyst , ferredoxin , anabaena variabilis , nitrogenase , nad+ kinase , oxidoreductase , photosystem i , anabaena , thylakoid , nadh dehydrogenase , biology , biochemistry , nadph dehydrogenase , dcmu , ferredoxin—nadp(+) reductase , dehydrogenase , chloroplast , flavoprotein , photochemistry , enzyme , chemistry , cyanobacteria , nitrogen fixation , photosynthesis , protein subunit , photosystem ii , bacteria , genetics , nitric oxide synthase , gene
In the light, the NADH/NAD redox couple acts as a more potent intermediate electron donor than NADPH/NADP for nitrogenase activity in heterocyst homogenates of Anabaena variabilis . This is due to different properties of thylakoid‐bound NADH dehydrogenase and ferredoxin: NADP oxidoreductase (EC 1.18.1.2), which oxidize NADH and NADPH, respectively. During nitrogenase activity in the light, a steady‐state reduction charge difference of a factor of 10 can be calculated between both pyridine nucleotide couples, with NADPH/NADP being more reduced. From this it is inferred that on heterocyst thylakoids NADH dehydrogenase, photosystem I, ferredoxin and ferredoxin: NADP oxidoreductase constitute an efficient light‐dependent transhydrogenase system.