Journal ArticleBiochemistry · October 7, 1997
To further understand the six-electron reductions of sulfite and nitrite catalyzed by the Escherichia coli sulfite reductase hemoprotein (SiRHP), we have determined crystallographic structures of the enzyme in complex with the inhibitors phosphate, carbon ...
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Journal ArticleBiochemistry · October 7, 1997
The active center of the Escherichia coli sulfite reductase hemoprotein (SiRHP) is exquisitely designed to catalyze the six-electron reductions of sulfite to sulfide and nitrite to ammonia. Refined high-resolution crystallographic structures of oxidized, t ...
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Journal ArticleScience · October 6, 1995
Fundamental chemical transformations for biogeochemical cycling of sulfur and nitrogen are catalyzed by sulfite and nitrite reductases. The crystallographic structure of Escherichia coli sulfite reductase hemoprotein (SiRHP), which catalyzes the concerted ...
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Journal ArticleBiochemistry · August 31, 1993
The heme protein subunit of sulfite reductase (SiR-HP; M(r) 64,000) from Escherichia coli as isolated contains the isobacteriochlorin siroheme exchange-coupled to a [4Fe-4S] cluster in the 2+ oxidation state. SiR-HP in the presence of a suitable electron d ...
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Journal ArticleBiochemistry · March 23, 1993
The isolated hemeprotein subunit of sulfite reductase (SiR-HP) from Escherichia coli consists of a high spin ferric isobacteriochlorin (siroheme) coupled to a diamagnetic [4Fe-4S]2+ cluster. When supplied with an artificial electron donor, such as methyl v ...
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Journal ArticleJ Bacteriol · January 1991
The flavoprotein and hemoprotein components of Escherichia coli B NADPH-sulfite reductase are encoded by cysJ and cysI, respectively. Plasmids containing these two genes overexpressed flavoprotein catalytic activity and apohemoprotein by 13- to 35-fold, bu ...
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Journal ArticleBiochem Biophys Res Commun · May 31, 1990
The reversible reduction and reoxidation of Escherichia coli sulfite reductase hemeprotein subunit at pH 9.9 produces high and low spin ferric species, the latter with properties distinct from any alkaline low spin yet reported. With virtually no effect on ...
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Journal ArticleJ Biol Chem · September 25, 1989
NADPH-sulfite reductase flavoprotein (SiR-FP) was purified from a Salmonella typhimurium cysG strain that does not synthesize the hemoprotein component of the sulfite reductase holoenzyme. cysJ, which codes for SiR-FP, was cloned from S. typhimurium LT7 an ...
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Journal ArticleJ Biol Chem · September 15, 1989
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 a monomer ...
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Journal ArticleBiochemistry · June 27, 1989
Resonance Raman (RR) spectra are reported for the hemoprotein subunit (SiR-HP) of Escherichia coli NADPH-sulfite reductase (EC 1.8.1.2) in various ligation and redox states. Comparison of the RR spectra of extracted siroheme and the mu-oxo FeIII dimer of o ...
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Journal ArticleBiochemistry · June 27, 1989
Resonance Raman (RR) spectra from the hemoprotein subunit of Escherichia coli sulfite reductase (SiR-HP) are examined in the low-frequency (200-500 cm-1) region where Fe-S stretching modes are expected. In spectra obtained with excitation in the siroheme S ...
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Journal ArticleBiochemistry · June 27, 1989
The vibrations of the bound diatomic heme ligands CO, CN-, and NO are investigated by resonance Raman spectroscopy in various redox states of Escherichia coli sulfite reductase hemoprotein, and assignments are generated by use of isotopically labeled ligan ...
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Journal ArticleBiochemistry · August 9, 1988
The oxidized forms of resting and sulfite-complexed Escherichia coli sulfite reductase heme protein subunit react with near-stoichiometric amounts of porphyrexide to produce what is best characterized as a ferrisiroheme pi cation radical. Addition of eithe ...
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Journal ArticleBiochemistry · July 12, 1988
The heme protein subunit of Escherichia coli sulfite reductase shows enhanced reactivity with its substrate and a number of other ligands after a cycle of reduction and reoxidation at alkaline pH. At pH 9.5 this variant of the enzyme possesses at least fou ...
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Journal ArticleBiochemistry · April 19, 1988
Optical and EPR spectroscopy of ferric heme proteins of the porphyrin, oxyporphyrin, and isobacteriochlorin classes has indicated that nitrite reacts with these proteins at the heme iron. Sulfite has been conclusively proven to react only with proteins con ...
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Journal ArticleBiochemistry · March 22, 1988
The saturation magnetizations of the sulfite complex of oxidized sulfite reductase and the nitrite complex of oxidized nitrite reductase have been measured to determine their spin state. Each shows the saturation magnetization signal of a spin S = 1/2 stat ...
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Journal ArticleBiochemistry · October 7, 1997
To further understand the six-electron reductions of sulfite and nitrite catalyzed by the Escherichia coli sulfite reductase hemoprotein (SiRHP), we have determined crystallographic structures of the enzyme in complex with the inhibitors phosphate, carbon ...
Full textLink to itemCite
Journal ArticleBiochemistry · October 7, 1997
The active center of the Escherichia coli sulfite reductase hemoprotein (SiRHP) is exquisitely designed to catalyze the six-electron reductions of sulfite to sulfide and nitrite to ammonia. Refined high-resolution crystallographic structures of oxidized, t ...
Full textLink to itemCite
Journal ArticleScience · October 6, 1995
Fundamental chemical transformations for biogeochemical cycling of sulfur and nitrogen are catalyzed by sulfite and nitrite reductases. The crystallographic structure of Escherichia coli sulfite reductase hemoprotein (SiRHP), which catalyzes the concerted ...
Full textLink to itemCite
Journal ArticleBiochemistry · August 31, 1993
The heme protein subunit of sulfite reductase (SiR-HP; M(r) 64,000) from Escherichia coli as isolated contains the isobacteriochlorin siroheme exchange-coupled to a [4Fe-4S] cluster in the 2+ oxidation state. SiR-HP in the presence of a suitable electron d ...
Full textLink to itemCite
Journal ArticleBiochemistry · March 23, 1993
The isolated hemeprotein subunit of sulfite reductase (SiR-HP) from Escherichia coli consists of a high spin ferric isobacteriochlorin (siroheme) coupled to a diamagnetic [4Fe-4S]2+ cluster. When supplied with an artificial electron donor, such as methyl v ...
Full textLink to itemCite
Journal ArticleJ Bacteriol · January 1991
The flavoprotein and hemoprotein components of Escherichia coli B NADPH-sulfite reductase are encoded by cysJ and cysI, respectively. Plasmids containing these two genes overexpressed flavoprotein catalytic activity and apohemoprotein by 13- to 35-fold, bu ...
Full textLink to itemCite
Journal ArticleBiochem Biophys Res Commun · May 31, 1990
The reversible reduction and reoxidation of Escherichia coli sulfite reductase hemeprotein subunit at pH 9.9 produces high and low spin ferric species, the latter with properties distinct from any alkaline low spin yet reported. With virtually no effect on ...
Full textLink to itemCite
Journal ArticleJ Biol Chem · September 25, 1989
NADPH-sulfite reductase flavoprotein (SiR-FP) was purified from a Salmonella typhimurium cysG strain that does not synthesize the hemoprotein component of the sulfite reductase holoenzyme. cysJ, which codes for SiR-FP, was cloned from S. typhimurium LT7 an ...
Link to itemCite
Journal ArticleJ Biol Chem · September 15, 1989
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 a monomer ...
Link to itemCite
Journal ArticleBiochemistry · June 27, 1989
Resonance Raman (RR) spectra are reported for the hemoprotein subunit (SiR-HP) of Escherichia coli NADPH-sulfite reductase (EC 1.8.1.2) in various ligation and redox states. Comparison of the RR spectra of extracted siroheme and the mu-oxo FeIII dimer of o ...
Full textLink to itemCite
Journal ArticleBiochemistry · June 27, 1989
Resonance Raman (RR) spectra from the hemoprotein subunit of Escherichia coli sulfite reductase (SiR-HP) are examined in the low-frequency (200-500 cm-1) region where Fe-S stretching modes are expected. In spectra obtained with excitation in the siroheme S ...
Full textLink to itemCite
Journal ArticleBiochemistry · June 27, 1989
The vibrations of the bound diatomic heme ligands CO, CN-, and NO are investigated by resonance Raman spectroscopy in various redox states of Escherichia coli sulfite reductase hemoprotein, and assignments are generated by use of isotopically labeled ligan ...
Full textLink to itemCite
Journal ArticleBiochemistry · August 9, 1988
The oxidized forms of resting and sulfite-complexed Escherichia coli sulfite reductase heme protein subunit react with near-stoichiometric amounts of porphyrexide to produce what is best characterized as a ferrisiroheme pi cation radical. Addition of eithe ...
Full textLink to itemCite
Journal ArticleBiochemistry · July 12, 1988
The heme protein subunit of Escherichia coli sulfite reductase shows enhanced reactivity with its substrate and a number of other ligands after a cycle of reduction and reoxidation at alkaline pH. At pH 9.5 this variant of the enzyme possesses at least fou ...
Full textLink to itemCite
Journal ArticleBiochemistry · April 19, 1988
Optical and EPR spectroscopy of ferric heme proteins of the porphyrin, oxyporphyrin, and isobacteriochlorin classes has indicated that nitrite reacts with these proteins at the heme iron. Sulfite has been conclusively proven to react only with proteins con ...
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Journal ArticleBiochemistry · March 22, 1988
The saturation magnetizations of the sulfite complex of oxidized sulfite reductase and the nitrite complex of oxidized nitrite reductase have been measured to determine their spin state. Each shows the saturation magnetization signal of a spin S = 1/2 stat ...
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Journal ArticleBiochemistry · August 12, 1986
We have employed electron-nuclear double resonance (ENDOR) spectroscopy to study the 57Fe hyperfine interactions in the bridged-siroheme [4Fe-4S] cluster that forms the catalytically active center of the two-electron-reduced hemoprotein subunit of Escheric ...
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Journal ArticleJ Biol Chem · August 5, 1986
Isolated hemoprotein subunits of Escherichia coli NADPH:sulfite reductase catalyze the 6-electron reduction of SO2-3 to S2-. The prosthetic groups of the hemoprotein, a siroheme and a Fe4S4 cluster, have been shown by spectroscopy to be tightly coupled. We ...
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Journal ArticleJournal of Biological Chemistry · January 1, 1986
Isolated hemoprotein subunits of Escherichia coli NADPH:sulfite reductase catalyze the 6-electron reduction of SO32- to S2-. The prosthetic groups of the hemoprotein, a siroheme and a Fe4S4 cluster, have been shown by spectroscopy to be tightly coupled. We ...
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Journal ArticleBiochemistry · December 31, 1985
We have employed electron-nuclear double resonance (ENDOR) spectroscopy to study the bridged siroheme--[Fe4S4] cluster that forms the catalytically active center of the oxidized hemoprotein subunit (SiRo) of Escherichia coli NADPH-sulfite reductase. The si ...
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Journal ArticleArch Biochem Biophys · March 1984
Purine hydroxylase II from Aspergillus nidulans contains a molybdenum cofactor very similar to that found in a number of other molybdenum-containing hydroxylases. (A. nidulans contains two purine hydroxylases, I and II, related to each other by possession ...
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Journal ArticleJournal of the American Chemical Society · January 1, 1984
Recent Mössbauer and EPR studies of the hemoprotein subunit (SiR) of E. coli sulfite reductase have shown that the siroheme and the [4Fe-4S] cluster are exchange coupled in a variety of states. Mössbauer studies of 2-electron-reduced SiR in the presence of ...
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Journal ArticleJ Biol Chem · September 25, 1983
We have studied the hemoprotein subunit (SiR) of Escherichia coli NADPH-sulfite reductase with Mössbauer spectroscopy in a variety of complexes and oxidation states. We demonstrated earlier for oxidized SiR (Christner, J. A., Münck, E., Janick, P. A., and ...
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Journal ArticleJ Biol Chem · September 25, 1983
Mössbauer studies of the hemoprotein subunit (SiR) of E. coli sulfite reductase have shown that the siroheme and the [4Fe-4S] cluster are exchange-coupled. Here we report Mössbauer studies of SiR complexed with either CO or CN- and of SiR in the presence o ...
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Journal ArticleJ Biol Chem · September 25, 1983
Formate dehydrogenase from Methanobacterium formicicum was examined by electron paramagnetic resonance spectroscopy. Although oxidized enzyme yielded no EPR signals over the temperature range 8-200 K, dithionite reduction resulted in generation of two para ...
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Journal ArticleJ Bacteriol · March 1983
Using spin labeling and spin trapping techniques in combination with electron paramagnetic resonance spectrometry, we have detected the formation of superoxide by whole cells of Methanobacterium formicicum under aerobic conditions in the presence and absen ...
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Journal ArticleBiochemistry · January 18, 1983
Janick & Siegel [Janick, P. A., & Siegel, L. M. (1982) Biochemistry 21, 3538-3547] showed that the EPR spectrum of the reduced Fe4S4 center (S = 1/2) in fully reduced native ("unligated") Escherichia coli NADPH-sulfite reductase hemoprotein subunit (SiR-HP ...
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Journal ArticleBiochemistry · January 1, 1983
Spinach ferredoxin-nitrite reductase (NiR) is a monomeric enzyme containing one siroheme (high-spin Fe3+) and one oxidized Fe4S4 cluster per active molecule. When NiR is photochemically reduced with ethylenediaminetetraacetate (EDTA)-deazaflavin, the free ...
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Journal ArticleBiochemistry · July 20, 1982
Rabbit liver aldehyde oxidase (AO), like milk xanthine oxidase (XO) and chicken liver xanthine dehydrogenase (XDH), possesses the following prosthetic groups: FAD, a functional Mo center, and two spectroscopically distinct iron-sulfur centers, one with gav ...
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Journal ArticleBiochemistry · July 20, 1982
The hemoprotein subunit (SiR-HP) of Escherichia coli NADPH-sulfite reductase contains one siroheme (high-spin Fe3+, D = 8 cm-1) and one oxidized Fe4S4 center per polypeptide. Christner et al. [Christner, J.A., Munck, E., Janick, P.A., & Siegel, L.M. (1981) ...
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Journal ArticleJ Biol Chem · June 10, 1982
Escherichia coli NADPH-sulfite reductase can be dissociated into an oligomeric flavoprotein and a monomeric hemoprotein (HP) subunit in 4 M urea. HP catalyzes stoichiometric 6-electron reductions of SO32- (to S2-) and of NO2-, as well as 2-electron reducti ...
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Journal ArticleBiochemistry · June 8, 1982
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, with subuni ...
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Journal ArticleBiochemistry · June 8, 1982
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 ethylenediaminetetraacetate (ED ...
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Journal ArticleBiochemistry · March 30, 1982
The relaxation behavior of the EPR signals of MoV, FAD semiquinone, and the reduced Fe/S I center was measured in the presence and absence of other paramagnetic centers in milk xanthine oxidase. Specific pairs of prosthetic groups were rendered paramagneti ...
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Journal ArticleJ Biol Chem · March 10, 1981
Escherichia coli NADPH-sulfite reductase is a complex hemoflavoprotein with an alpha 8 beta 4 subunit structure. The beta-subunits each contain one siroheme and a tetranuclear iron-sulfur center (Fe4S4). Isolated beta-monomers can catalyze the 6-electron r ...
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Journal ArticleJ Biol Chem · February 25, 1979
EPR spectroscopic and chemical analyses of spinach nitrite reductase show that the enzyme contains one reducible iron-sulfur center, and one site for binding either cyanide or nitrite, per siroheme. The heme is nearly all in the high spin ferric state in t ...
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Journal ArticleJournal of the American Chemical Society · January 1, 1978
Isolation of metabolites from cobalt-free incubations of Propionibacterium shermanii extracts has uncovered a new intermediate (C42H46N4O16) related to the corrin biosynthetic pathway whose physical properties are identical with those of sirohydrochlorin. ...
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Journal ArticleBiochem J · December 1, 1977
Sirohaem is a new type of haem that has been detected as a prosthetic group of several bacterial and plant enzymes that catalyse the six-electron reductions of sulphite to sulphide or of nitrite to NH(3). When a methionine-requiring mutant of Escherichia c ...
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Journal ArticleJ Biol Chem · October 25, 1975
The Neurospora crassa assimilatory nitrite reductase (EC 1.6.6.4) catalyzes the NADPH-dependent reduction of nitrite to ammonia, a 6-electron transfer reaction. Highly purified preparations of this enzyme exhibit absorption spectra which suggest the presen ...
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Journal ArticleProc Natl Acad Sci U S A · March 1974
Ferredoxin-nitrite reductase (EC 1.7.7.1) of spinach, an enzyme that catalyzes the six-electron reduction of nitrite to ammonia, contains siroheme, the new type of prosthetic group recently found in several sulfite reductases (both assimilatory and dissimi ...
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