Related ArticlesProton NMR of Escherichia coli sulfite reductase: the unligated hemeprotein subunit.
Biochemistry. 1993 Mar 23;32(11):2853-67
Authors: Kaufman J, Spicer LD, Siegel LM
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 viologen cation radical, SiR-HP can catalyze the six electron reductions of sulfite to sulfide and nitrite to ammonia. Thus, the hemeprotein subunit appears to represent the minimal protein structure required for multielectron reductase activity. Proton magnetic resonance spectra are reported for the first time on unligated SiR-HP at 300 MHz in all three redox states. The NMR spectrum of high spin ferric siroheme at pH 6.0 was obtained for the purpose of comparing its spectrum with that of oxidized SiR-HP. On the basis of line widths, T1 measurements, and 1D NOE experiments, preliminary assignments have been made for the oxidized enzyme in solution. The pH profile of oxidized SiR-HP is unusual in that a single resonance shows a 9 ppm shift over a range of only 3 pH units with an apparent pK = 6.7 +/- 0.2. Resonances arising from the beta-CH2 protons of cluster cysteines have been assigned using deuterium substitution for all redox states. One beta-CH2 resonance has been tentatively assigned to the bridging cysteine on the basis of chemical shift, T1, line width, and the presence of NOEs to protons from the siroheme ring. The observed pattern of hyperfine shifts can be used as a probe to measure the degree of coupling between siroheme and cluster in solution. The cluster iron sites of the resting (oxidized) enzyme are found to possess both positive and negative spin density which is in good agreement with Mossbauer results on frozen enzyme. The NMR spectrum of the 1-electron reduced form of SiR-HP is consistent with an intermediate spin (S = 1) siroheme. Intermediate spin Fe(II) hemes have only been previously observed in 4-coordinate model compounds. However, the amount of electron density transferred to the cluster, as measured by the isotropic shift of beta-CH2 resonances, is comparable to that present in the fully oxidized enzyme despite diminution of the total amount of unpaired spin density available. Addition of a second electron to SiR-HP, besides generating a reduced S = 1/2 cluster with both upfield and downfield shifted cysteine resonances, converts siroheme to the high spin (S = 2) ferrous state.(ABSTRACT TRUNCATED AT 400 WORDS)
[NMR paper] Elucidation of the epsilon-theta subunit interface of Escherichia coli DNA polymerase
Elucidation of the epsilon-theta subunit interface of Escherichia coli DNA polymerase III by NMR spectroscopy.
Related Articles Elucidation of the epsilon-theta subunit interface of Escherichia coli DNA polymerase III by NMR spectroscopy.
Biochemistry. 2003 Apr 8;42(13):3635-44
Authors: DeRose EF, Darden T, Harvey S, Gabel S, Perrino FW, Schaaper RM, London RE
The DNA polymerase III holoenzyme (HE) is the primary replicative polymerase of Escherichia coli. The epsilon (epsilon) subunit of HE provides the 3'-->5' exonucleolytic proofreading...
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[NMR paper] Refolding of [6-19F]tryptophan-labeled Escherichia coli dihydrofolate reductase in th
Refolding of tryptophan-labeled Escherichia coli dihydrofolate reductase in the presence of ligand: a stopped-flow NMR spectroscopy study.
Related Articles Refolding of tryptophan-labeled Escherichia coli dihydrofolate reductase in the presence of ligand: a stopped-flow NMR spectroscopy study.
Biochemistry. 1998 Jan 6;37(1):387-98
Authors: Hoeltzli SD, Frieden C
Escherichia coli dihydrofolate reductase contains five tryptophan residues that are spatially distributed throughout the protein and located in different secondary structural elements....
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[NMR paper] Structural features of the epsilon subunit of the Escherichia coli ATP synthase deter
Structural features of the epsilon subunit of the Escherichia coli ATP synthase determined by NMR spectroscopy.
Related Articles Structural features of the epsilon subunit of the Escherichia coli ATP synthase determined by NMR spectroscopy.
Nat Struct Biol. 1995 Nov;2(11):961-7
Authors: Wilkens S, Dahlquist FW, McIntosh LP, Donaldson LW, Capaldi RA
The tertiary fold of the epsilon subunit of the Escherichia coli F1F0 ATPsynthase (ECF1F0) has been determined by two- and three-dimensional heteronuclear (13C, 15N) NMR spectroscopy. The epsilon...
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[NMR paper] Proton NMR of Escherichia coli sulfite reductase: studies of the heme protein subunit
Proton NMR of Escherichia coli sulfite reductase: studies of the heme protein subunit with added ligands.
Related Articles Proton NMR of Escherichia coli sulfite reductase: studies of the heme protein subunit with added ligands.
Biochemistry. 1993 Aug 31;32(34):8782-91
Authors: Kaufman J, Siegel LM, Spicer LD
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 cluster in the 2+ oxidation state. SiR-HP in the presence of a suitable...
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[NMR paper] Proton NMR study on a histone-like protein, HU alpha, from Escherichia coli and its c
Proton NMR study on a histone-like protein, HU alpha, from Escherichia coli and its complex with oligo DNAs.
Related Articles Proton NMR study on a histone-like protein, HU alpha, from Escherichia coli and its complex with oligo DNAs.
Biol Pharm Bull. 1993 May;16(5):437-43
Authors: Shindo H, Kurumizaka H, Furubayashi A, Sakuma C, Matsumoto U, Yanagida A, Goshima N, Kano Y, Imamoto F
It was confirmed that the flexible arm region of HU alpha forms an antiparallel beta-sheet and that all of the residues of phenylalanines, together with some of...
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[NMR paper] 13C NMR studies of complexes of Escherichia coli dihydrofolate reductase formed with
13C NMR studies of complexes of Escherichia coli dihydrofolate reductase formed with methotrexate and with folic acid.
http://www.ncbi.nlm.nih.gov/corehtml/query/egifs/http:--linkinghub.elsevier.com-ihub-images-PubMedLink.gif Related Articles 13C NMR studies of complexes of Escherichia coli dihydrofolate reductase formed with methotrexate and with folic acid.
FEBS Lett. 1992 Nov 9;312(2-3):147-51
Authors: Cheung HT, Birdsall B, Feeney J
13C NMR studies of 13C-labelled ligands bound to dihydrofolate reductase provide (DHFR) a powerful means of...
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[NMR paper] Studies on ribonucleoside-diphosphate reductase from Escherichia coli. The product dC
Studies on ribonucleoside-diphosphate reductase from Escherichia coli. The product dCDP is a competitive inhibitor and functions as a spectroscopic probe for the substrate binding site; demonstration by enzyme kinetics and 1H NMR.
http://www.ncbi.nlm.nih.gov/corehtml/query/egifs/http:--www3.interscience.wiley.com-aboutus-images-wiley_interscience_pubmed_logo_FREE_120x27.gif Related Articles Studies on ribonucleoside-diphosphate reductase from Escherichia coli. The product dCDP is a competitive inhibitor and functions as a spectroscopic probe for the substrate binding site;...
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[NMR paper] Proton-transfer effects in the active-site region of Escherichia coli thioredoxin usi
Proton-transfer effects in the active-site region of Escherichia coli thioredoxin using two-dimensional 1H NMR.
Related Articles Proton-transfer effects in the active-site region of Escherichia coli thioredoxin using two-dimensional 1H NMR.
Biochemistry. 1991 Apr 30;30(17):4262-8
Authors: Dyson HJ, Tennant LL, Holmgren A
A series of two-dimensional (2D) correlated 1H NMR spectra of reduced and oxidized Escherichia coli thioredoxin have been used to probe the effects of pH in the vicinity of the active site, -Cys32-Gly-Pro-Cys35-, using the...