The water-soluble carbodiimide, N-ethyl-3-(3-dimethylaminopropyl)carbodiimide was found to effectively cross-link ferredoxin to ferredoxin-NADP+ reductase. The covalent complex has a stoichiometry of 1 mol of ferredoxin per mol of the reductase. The flavoprotein moiety of the cross-linked complex maintains most of its diaphorase activity and more interestingly has gained the capacity to catalyze the NADPH-cytochrome c reaction without addition of free ferredoxin in the assay mixture. Furthermore, the cross-linked complex binds NADP+ with a K(d) = 88 μM at an ionic strength of 0.02 M. These results show that a ternary complex among the reductase and its substrates can be formed, suggesting that the binding sites for ferredoxin and the pyridine nucleotides are distinct. The bound ferredoxin can interact with cytochrome c; the iron-sulfur cluster of the cross-linked complex is shown to be reduced under anaerobic conditions by NADPH and to be required for the catalysis of the NADPH-cytochrome c reductase reaction. The cross-linked complex, added to thylakoids inhibited by the antibody against the reductase, catalyzes the H2O-cytochrome c photoreduction, which suggests that the ferredoxin moiety of the complex can interact with its electron donor in the photosynthetic chain. Restoration of NADP+ photoreduction requires the addition of free ferredoxin.
A cross-linked complex between ferredoxin and ferredoxin-NADP+ reductase / G. Zanetti, A. Aliverti, B. Curti. - In: THE JOURNAL OF BIOLOGICAL CHEMISTRY. - ISSN 0021-9258. - 259:10(1984 May 25), pp. 6153-6157.
|Titolo:||A cross-linked complex between ferredoxin and ferredoxin-NADP+ reductase|
ZANETTI, GIULIANA (Primo)
ALIVERTI, ALESSANDRO (Secondo)
CURTI, BRUNO (Ultimo)
|Parole Chiave:||protein ; enzyme ; flavoprotein ; iron-sulfur protein ; protein-protein complex ; protein-protein interaction ; protein recognition ; protein modification ; photosynthesis ; ternary complex ; biological oxidoreduction ; chloroplast ; catalytic mechanism ; protein engineering|
|Settore Scientifico Disciplinare:||Settore BIO/10 - Biochimica|
Settore BIO/11 - Biologia Molecolare
Settore BIO/04 - Fisiologia Vegetale
|Data di pubblicazione:||25-mag-1984|
|Appare nelle tipologie:||01 - Articolo su periodico|