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 ?
For example, a chlorophycean ferredoxin was identified during desiccation (Table 2).
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.
aestivum petF gene for e-155 97 ferredoxin, X75089 3-131 BQ134673 T.
During illumination, oxygen radicals are generated mainly by leakage of electrons from PSI and from ferredoxin (Asada & Takahashi, 1987).
The N-terminal 15 amino acids showed homology with several ferredoxin sulfite reductases of higher plants.
1998), sweet pepper derived ferredoxin like protein (pflp) gene (Chan et al.
coli HMBDP reductase reduces HMBDP in the presence of ferredoxin and NADPH to yield a 5:1 mixture of IPP and DMAPP.
Primary structure of the precursor and mature forms of stearoyl-acyl carrier protein desaturase from safflower embryos and requirement of ferredoxin for enzyme activity.
Ferredoxin has a significant role in nitrogen dioxide and sulphate reduction, the assimilation of N by root nodule bacteria and frees living N-fixing soil bacteria (Scherer et al.
The S from the APS may then be attached to a carrier molecule by APS-sulfotransferase and then reduced to bound sulfite with reduced ferredoxin serving as the electron donor (Brunold, 1990).
Ferredoxin has a significant role in nitrogen dioxide and sulfate reduction and assimilation of N by root nodule and free living N-fixing soil bacteria (Scherer, 2008; Scherer et al.