Scholars@Duke
Lewis M. Siegel

Lewis M. Siegel

Professor Emeritus of Biochemistry
Biochemistry
lmsiegel@duke.edu
Box 90459, Durham, NC 27708-0067
251 Trent, Durham, NC 27708

Selected Publications

Probing the catalytic mechanism of sulfite reductase by X-ray crystallography: structures of the Escherichia coli hemoprotein in complex with substrates, inhibitors, intermediates, and products.

Journal Article Biochemistry · 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 text Link to item Cite

Structures of the siroheme- and Fe4S4-containing active center of sulfite reductase in different states of oxidation: heme activation via reduction-gated exogenous ligand exchange.

Journal Article Biochemistry · 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 text Link to item Cite

Sulfite reductase structure at 1.6 A: evolution and catalysis for reduction of inorganic anions.

Journal Article Science · 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 text Link to item Cite

Proton NMR of Escherichia coli sulfite reductase: studies of the heme protein subunit with added ligands.

Journal Article Biochemistry · 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 text Link to item Cite

Proton NMR of Escherichia coli sulfite reductase: the unligated hemeprotein subunit.

Journal Article Biochemistry · 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 text Link to item Cite

High-level expression of Escherichia coli NADPH-sulfite reductase: requirement for a cloned cysG plasmid to overcome limiting siroheme cofactor.

Journal Article J 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 text Link to item Cite

Alkaline low spin form of sulfite reductase hemeprotein subunit.

Journal Article Biochem 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 text Link to item Cite

Characterization of the flavoprotein moieties of NADPH-sulfite reductase from Salmonella typhimurium and Escherichia coli. Physicochemical and catalytic properties, amino acid sequence deduced from DNA sequence of cysJ, and comparison with NADPH-cytochrome P-450 reductase.

Journal Article J 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 item Cite

Characterization of the cysJIH regions of Salmonella typhimurium and Escherichia coli B. DNA sequences of cysI and cysH and a model for the siroheme-Fe4S4 active center of sulfite reductase hemoprotein based on amino acid homology with spinach nitrite reductase.

Journal Article J 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 item Cite

Resonance Raman studies of Escherichia coli sulfite reductase hemoprotein. 1. Siroheme vibrational modes.

Journal Article Biochemistry · 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 text Link to item Cite

Resonance Raman studies of Escherichia coli sulfite reductase hemoprotein. 2. Fe4S4 cluster vibrational modes.

Journal Article Biochemistry · 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 text Link to item Cite

Resonance Raman studies of Escherichia coli sulfite reductase hemoprotein. 3. Bound ligand vibrational modes.

Journal Article Biochemistry · 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 text Link to item Cite

NEW INSIGHTS INTO THE SIROHEME-FE4S4 INTERACTION IN SULFITE REDUCTASE FROM RESONANCE RAMAN-SPECTROSCOPY

Journal Article ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY · September 25, 1988 Link to item Cite

Superoxidized states of Escherichia coli sulfite reductase heme protein subunit.

Journal Article Biochemistry · 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 text Link to item Cite

Activated conformers of Escherichia coli sulfite reductase heme protein subunit.

Journal Article Biochemistry · 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 text Link to item Cite

On the reaction of ferric heme proteins with nitrite and sulfite.

Journal Article Biochemistry · 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 ... Full text Link to item Cite

Magnetization of the sulfite and nitrite complexes of oxidized sulfite and nitrite reductases: EPR silent spin S = 1/2 states.

Journal Article Biochemistry · 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 ... Full text Link to item Cite

THE SULFITE COMPLEX OF SULFITE REDUCTASE - ELECTRON-PARAMAGNETIC-RES SILENT SPIN S= 1/2 STATE

Journal Article ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY · August 30, 1987 Link to item Cite

57Fe and 1H electron-nuclear double resonance of three doubly reduced states Escherichia coli sulfite reductase.

Journal Article Biochemistry · 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 ... Full text Link to item Cite

The heme and Fe4S4 cluster in the crystallographic structure of Escherichia coli sulfite reductase.

Journal Article J 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 ... Link to item Cite

The heme and Fe4S4 cluster in the crystallographic structure of Escherichia coli sulfite reductase

Journal Article Journal 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, ha ... Cite

Electron-nuclear double resonance studies of oxidized Escherichia coli sulfite reductase: 1H, 14N, and 57Fe measurements.

Journal Article Biochemistry · 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 ... Full text Link to item Cite

Optical and electron paramagnetic resonance spectroscopic studies on purine hydroxylase II from Aspergillus nidulans.

Journal Article Arch 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 ... Full text Link to item Cite

Exchange Coupling between Siroheme and [4Fe-4S] Cluster in E. Coli Sulfite Reductase. Mössbauer Studies and Coupling Models for a 2-Electron Reduced Enzyme State and Complexes with Sulfide

Journal Article Journal 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 ... Full text Cite

Mössbauer evidence for exchange-coupled siroheme and [4Fe-4S] prosthetic groups in Escherichia coli sulfite reductase. Studies of the reduced states and of a nitrite turnover complex.

Journal Article J 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 ... Link to item Cite

Mössbauer studies of Escherichia coli sulfite reductase complexes with carbon monoxide and cyanide. Exchange coupling and intrinsic properties of the [4Fe-4S] cluster.

Journal Article J 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 ... Link to item Cite

Formate dehydrogenase from Methanobacterium formicicum. Electron paramagnetic resonance spectroscopy of the molybdenum and iron-sulfur centers.

Journal Article J 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 ... Link to item Cite

Evidence for formation of superoxide and formate radicals in Methanobacterium formicicum.

Journal Article J 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 ... Full text Link to item Cite

Electron paramagnetic resonance and optical evidence for interaction between siroheme and Fe4S4 prosthetic groups in complexes of Escherichia coli sulfite reductase hemoprotein with added ligands.

Journal Article Biochemistry · 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 ... Full text Link to item Cite

SIROHEME-FE4S4 INTERACTION IN SPINACH NITRITE REDUCTASE (NIR)

Journal Article FEDERATION PROCEEDINGS · January 1, 1983 Link to item Cite

Electron Paramagnetic Resonance and Optical Spectroscopic Evidence for Interaction between Siroheme and Tetranuclear Iron-Sulfur Center Prosthetic Groups in Spinach Ferredoxin-Nitrite Reductase

Journal Article Biochemistry · 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 ethylenediaminetetraacet ... Full text Cite

Properties of the prosthetic groups of rabbit liver aldehyde oxidase: a comparison of molybdenum hydroxylase enzymes.

Journal Article Biochemistry · 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 ... Full text Link to item Cite

Electron paramagnetic resonance and optical spectroscopic evidence for interaction between siroheme and Fe4S4 prosthetic groups in Escherichia coli sulfite reductase hemoprotein subunit.

Journal Article Biochemistry · 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) ... Full text Link to item Cite

Escherichia coli sulfite reductase hemoprotein subunit. Prosthetic groups, catalytic parameters, and ligand complexes.

Journal Article J 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 ... Link to item Cite

Spinach siroheme enzymes: Isolation and characterization of ferredoxin-sulfite reductase and comparison of properties with ferredoxin-nitrite reductase.

Journal Article Biochemistry · 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 ... Full text Link to item Cite

Evidence for siroheme-Fe4S4 interaction in spinach ferredoxin-sulfite reductase.

Journal Article Biochemistry · 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 ... Full text Link to item Cite

Magnetic interactions in milk xanthine oxidase.

Journal Article Biochemistry · 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 ... Full text Link to item Cite

METHANOGENESIS - A NOVEL MO CENTER IN METHANOBACTERIUM-FORMICICUM

Journal Article FEDERATION PROCEEDINGS · January 1, 1982 Link to item Cite

Mössbauer spectroscopic studies of Escherichia coli sulfite reductase. Evidence for coupling between the siroheme and Fe4S4 cluster prosthetic groups.

Journal Article J 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 ... Link to item Cite

MAGNETIC-INTERACTIONS IN XANTHINE-OXIDASE (XO)

Journal Article FEDERATION PROCEEDINGS · January 1, 1981 Link to item Cite

EFFECT OF PH ON THE REDOX POTENTIALS OF MILK XANTHINE-OXIDASE (XO)

Journal Article FEDERATION PROCEEDINGS · January 1, 1980 Link to item Cite

Identification of the iron-sulfur center of spinach ferredoxin-nitrite reductase as a tetranuclear center, and preliminary EPR studies of mechanism.

Journal Article J 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 ... Link to item Cite

Sirohydrochlorin.1 Prosthetic Group of Sulfite and Nitrite Reductases and Its Role in the Biosynthesis of Vitamin B12

Journal Article Journal 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. ... Full text Cite

SPINACH-FERREDOXIN-SULFITE REDUCTASE (SIR)

Journal Article PLANT PHYSIOLOGY · January 1, 1978 Link to item Cite

Incorporation of methionine-derived methyl groups into sirohaem by Escherichia coli.

Journal Article Biochem 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 ... Full text Link to item Cite

Siroheme: a prosthetic group of the Neurospora crassa assimilatory nitrite reductase.

Journal Article J 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 ... Link to item Cite

Siroheme: a new prosthetic group participating in six-electron reduction reactions catalyzed by both sulfite and nitrite reductases.

Journal Article Proc 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 ... Full text Link to item Cite

Flavin interaction in NADPH-sulfite reductase.

Journal Article Z Naturforsch B Anorg Chem Org Chem Biochem Biophys Biol · September 1972 Full text Link to item Cite