Ferredoxin


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Related to Ferredoxin: Plastocyanin, Plastoquinone

Ferredoxin

 

any of a group of water-soluble proteins whose molecules contain iron atoms in nonheme form bonded to labile sulfur atoms. All ferredoxins are both enzymes and electron carriers with a highly negative redox potential (–0.39 to –0.49 volt). They are known to occur in bacteria and in the chloroplasts of plants.

All known ferredoxins are composed of a single polypeptide chain. Ferredoxins in bacteria (molecular weight, 5,500–10,000; 55–81 amino acid residues) contain from three (Chromatium) to eight (Clostridium) Fe atoms per molecule and an equal number of labile sulfur atoms. They participate in the fixation of atmospheric nitrogen and the reduction of the latter to ammonia, in the oxidation of gaseous hydrogen, and in the reduction of nicotinamide adenine dinucleotide phosphate (NADP) through the light reactions of photosynthesis in photosynthesizing bacteria.

Ferredoxins in chloroplasts (molecular weight, 11,500–13,000; 96–97 amino acid residues) contain two iron atoms bound to the protein by two sulfur atoms of cysteine molecules; the iron atoms are also bound to each other by two sulfur atoms. These ferredoxins figure in the photoreduction of NADP during photosynthesis. The sequence of amino acid residues has been determined for a number of bacterial and plant ferredoxins. A chemical synthesis of the peptide chain of the ferredoxins in the bacterium Clostridium pasteurinianum has been carried out.

REFERENCES

Mukhin, E. N. “Rol’ ferredoksina v fotosinteze.” Uspekhi sovremennoi biologii, 1969, vol. 67, no. 2.
Buchanan, B. B., and D. J. Arnon. “Ferredoxins.” Advances in Enzymology, 1970, vol. 33.

S. A. OSTROUMOV

References in periodicals archive ?
Hase, "Differential interaction of maize root ferredoxin:NADP+ oxidoreductase with photosynthetic and non-photosynthetic ferredoxin isoproteins," Plant Physiology, vol.
1:45 CHANGES IN EXPRESSION LEVELS OF FERREDOXIN:SULFITE REDUCTASE WITH CELL AGE IN A SOYBEAN SUSPENSION CULTURE
For example, a chlorophycean ferredoxin was identified during desiccation (Table 2).
Chitosan powder (medium grade, 99.9% purity) and ferredoxin were purchased from Sigma Aldrich Ltd.
(2002) Genetic analysis of the archaeon Methanosarcina barkeri Fusaro reveals a central role for Ech hydrogenase and ferredoxin in methanogenesis and carbon fixation.
The expression of a plant-type ferredoxin redox system provides molecular evidence for a plastid in the early dinoflagellate Perkinsus marinus.
High expression of genes for photosynthesis (rbcS, rbcL, photosystem I antenna protein, oxygen evolving photosystem II protein, glutaredoxin, ferredoxin, chl a/b-binding protein, and chloroplast inner envelope protein) and reactive oxygen species (ROS) scavenging (zeaxanthin epoxidase, glutathione S-reductase, glutathione peroxidase, and catalase) in the lemma/palea is an indication that these organs have a strong photosynthetic activity and require protection from ROS produced during the light reaction of photosynthesis.
One nucleoid associated protein is DCP68, which was identified from Glycine max suspension cells was identified as ferredoxin:sulfite reductase.
PMA inhibits both Hill activity and photophosphorylation (Siegenlthaler & Packer, 1965), as well as the dark reduction of cytochrome [C.sub.554] in whole cells of Chlamydomonas reinhardi, and inhibits either ferredoxin or ferredoxin-NADP oxidoreductase (Hiyama et al., 1970).
Chan, a chemist at the California Institute of Technology in Pasadena, and his colleagues report their determination of the structure of one of the bacterium's unusual enzymes, aldehyde ferredoxin oxidoreductase (AOR).
In addition, the higher the Fv, the greater will be the ability of pigments to transfer energy of expelled electrons to form the NADPH reducing agent, ATP, and ferredoxin reductase (FdR), and therefore the greater will be the C[O.sub.2] assimilation capacity of the plant.
The IP phase of the OJIP curve is related to electron transfer through PSI and the reduction of electron congestion caused by a transient block on the acceptor side of PSI due to inactivation of the ferredoxin NADP + reductase (Strasser et al., 2010).