EurekaMag.com logo
+ Site Statistics
References:
47,893,527
Abstracts:
28,296,643
+ Search Articles
+ Subscribe to Site Feeds
EurekaMag Most Shared ContentMost Shared
EurekaMag PDF Full Text ContentPDF Full Text
+ PDF Full Text
Request PDF Full TextRequest PDF Full Text
+ Follow Us
Follow on FacebookFollow on Facebook
Follow on TwitterFollow on Twitter
Follow on Google+Follow on Google+
Follow on LinkedInFollow on LinkedIn

+ Translate

Evidence of siroheme tetra nuclear iron sulfur center interaction in spinach ferredoxin sulfite reductase


, : Evidence of siroheme tetra nuclear iron sulfur center interaction in spinach ferredoxin sulfite reductase. Biochemistry 21(12): 2905-2909

Spinach ferredoxin-sulfite reductase (SiR) contains 1 siroheme and one Fe4S4 center per polypeptide subunit. The heme is entirely in the high-spin Fe3+ state in the oxidized enzyme. When SiR is photochemically reduced with ethylenediaminetetraacetate (EDTA)-deazaflavin, the free enzyme and its CN- and CO complexes show changes in absorption spectra associated with the heme even after the heme has been reduced from the Fe3+ to the Fe2+ state. With CO- or CN--SIR, these spectral changes are associated with the appearance of a classical g = 1.94 type of EPR spectrum characteristic of reduced Fe4S4 centers. The line shapes and exact g values of the g = 1.94 EPR spectra vary with the nature of the ligand bound to the heme Fe. Photoreduction of free SiR results in production of a novel type of EPR signal, with g = 2.48, 2.34, and 2.08 in the fully reduced enzyme; this signal accounts for 0.6 spin per heme. (A small g = 1.94 type EPR signal, representing 0.2 spin per heme, is also found.) These data suggest the presence of a strong magnetic interaction between the siroheme and Fe4S4 centers in spinach SiR, this interaction giving rise to different EPR signals depending on the spin state of the heme Fe in the reduced enzyme.


Accession: 005411732

Submit PDF Full Text: Here


Submit PDF Full Text

No spam - Every submission is manually reviewed

Due to poor quality, we do not accept files from Researchgate

Submitted PDF Full Texts will always be free for everyone
(We only charge for PDFs that we need to acquire)

Select a PDF file:
Close
Close

Related references

Wilkerson, J.O.; Janick, P.A.; Siegel, L.M., 1983: Epr and optical spectroscopic evidence for interaction between siro heme and tetra nuclear iron sulfur center prosthetic groups in spinach ferredoxin nitrate reductase ec 1.7.7.1. Spinach ferrodoxin-nitrite reductase (NiR) is a monomeric enzyme containing 1 siroheme (high-spin Fe3+) and 1 oxidized Fe4S4 cluster per active molecule. When NiR is photochemically reduced with EDTA-deazaflavin, the free enzyme and its CN- comple...

Wilkerson, J.; Janick, P.; Siegel, L., 1983: Electron paramagnetic resonance and optical spectroscopic evidence for interaction between siroheme and tetranuclear iron-sulfur center prosthetic groups in spinach ferredoxin-nitrite reductase. Biochemistry 22(21): 5048-5054

Siegel L.M.; Wilkerson J.O.; Janick P.A., 1987: Structural studies on the siroheme 4 iron 4 sulfur cluster active centers of spinach ferredoxin nitrite reductase and escherichia coli sulfite reductase. Ullrich, W R , Et Al (Ed ) Inorganic Nitrogen Metabolism; Symposium Held at A Meeting Of The Federation Of European Societies Of Plant Physiology, Strasbourg, France, 1984 Xiv+295p Springer-Verlag New York, Inc : Secaucus, New Jersey, Usa; Berlin, West Germany Illus 118-122

Krueger, R.J.; Siegel, L.M., 1982: Evidence for siroheme-Fe4S4 interaction in spinach ferredoxin-sulfite reductase. Spinach ferredoxin-sulfite reductase (SiR) contains one siroheme and one Fe4S4 center per polypeptide subunit. The heme is entirely in the high-spin Fe3+ state in the oxidized enzyme. When SiR is photochemically reduced with ethylenediaminetetraac...

Janick P.A.; Siegel L.M., 1982: Epr and optical spectroscopic evidence for interaction between siro heme and tetra nuclear iron sulfur center prosthetic groups in escherichia coli sulfite reductase hemo protein subunit. The hemoprotein subunit (SiR-HP) of E. coli NADPH-sulfite reductase contains 1 siroheme (high-spin Fe3+, D = 8 cm-1) and 1 oxidized Fe4S4 center per polypeptide. Christner et al. have shown by Mossbauer spectroscopy that the 2 prosthetic groups of...

Janick P.A.; Siegel L.M., 1983: Epr and optical evidence for interaction between siro heme and tetra nuclear iron sulfur center prosthetic groups in complexes of escherichia coli sulfite reductase hemo protein with added ligands. The EPR spectrum of the reduced Fe4S4 center (S = 1/2) in fully reduced native (unligated) E. coli NADPH-sulfite reductase hemoprotein subunit (SiR-HP) is perturbed by interaction with paramagnetic ferrous siroheme (S = 1 or 2) to yield several no...

Huynh B.H.; Kang L.; Der Vartanian D.V.; Peck H.D.Jr; Legall J., 1984: Characterization of a sulfite reductase from desulfovibrio vulgaris evidence for the presence of a low spin siroheme and an exchange coupled siroheme 4 iron 4 sulfur unit. A low MW (MW = 27,200) sulfite reductase from D. vulgaris (Hildenborough, NCIB 8303) with Mossbauer, EPR and chemical techniques was studied. This sulfite reductase contains 1 siroheme and 1 [4Fe-4S]cluster. As purified, the siroheme is low-spin f...

Krueger, R.J.; Siegel, L.M., 1982: Spinach siroheme enzymes: Isolation and characterization of ferredoxin-sulfite reductase and comparison of properties with ferredoxin-nitrite reductase. Sulfite reductase (SiR) has been purified to homogeneity from spinach leaves. Two forms of the enzyme were separated by hydroxylapatite chromatography. One, with subunit Mr 69 000 appears to be proteolytically cleaved to give rise to the other, wi...

Aparicio, P.J.; Knaff, D.B.; Malkin, R., 1975: The role of an iron-sulfur center and siroheme in spinach nitrite reductase. Purified spinach nitrite reductase, a protein that contains siroheme, is characterized by absorption maxima in the visible region at 385 and 573 nm. On addition of the substrate nitrite, the bands shift to 360 and 570 nm. Dithionite also causes sh...

Ostrowski J.; W.J.Y.; Rueger D.C.; Miller B.E.; Seigel L.M.; Kredich N.M., 1989: Characterization of the cys jih regions of salmonella typhimurium and escherichia coli b dna sequences of cys i and cys h and a model for the siroheme 4 iron 4 sulfur active centers of sulfite reductase hemoprotein based on amino acid homology with spinach nitrite reductase. The hemoprotein component of Salmonella typhimurium sulfite reductase (NADPH) (EC 1.8.1.2) was purified to homogeneity from cysJ266, a mutant strain lacking sulfite reductase flavoprotein. The siroheme- and Fe4S4-containing enzyme was isolated as...