A Q-Band Pulse EPR/ENDOR Spectrometer and the Implementation of Advanced One- and Two-Dimensional Pulse EPR Methodology

Gromov, Igor; Shane, J. J.; Forrer, Jörg; Rakhmatoullin, R.; Rozentzwaig, Yu.; Schweiger, Arthur

doi:10.1006/jmre.2001.2298

Cited by 81 publications

(77 citation statements)

References 27 publications

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“…X-band measurements were per-formed on a Bruker ElexSys 580 spectrometer equipped with a Bruker split-ring or dielectric resonator (ER 4118X -MS3 or ER 4118 MD5). Q-band measurements were performed on a home-built high power spectrometer [48,49] equipped with a custom resonator for samples with 3 mm outer diameter [50]. The S-band measurements were performed on a home built spectrometer [51].…”

Section: Epr Measurementsmentioning

confidence: 99%

Distance determination from dysprosium induced relaxation enhancement: a case study on membrane-inserted WALP23 polypeptides

et al. 2013

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Abstract. Membrane incorporated synthetic α-helical polypeptides labeled with Dy(III) chelate complexes and nitroxide radicals were studied by the inversion recovery (IR) technique and Dy(III)-nitroxide distances were obtained. A comparison of obtained distances with the previously reported Gd(III)-nitroxide pulse double electron-electron resonance (DEER or PELDOR) calibration data was performed and revealed reliability of the IR-based technique for the distance determination in membrane-incorporated biomacromolecules. The presented distance determination technique is 'spectroscopically orthogonal' to DEER-based distance measurements and can be potentially combined with DEER to study multiply spin-labeled biomacromolecules. The key steps of the data processing, the types of obtained distance information and the areas of possible application of the technique are discussed.

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Section: Epr Measurementsmentioning

confidence: 99%

Distance determination from dysprosium induced relaxation enhancement: a case study on membrane-inserted WALP23 polypeptides

et al. 2013

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“…EPR spectroscopy [30] The Q-band (35 GHz) experiments were carried out on an instrument built in-house [31] and equipped with a helium gas-flow cryostat from Oxford Instruments, Inc. (Beckenham, UK). All X-and W-band (9.7/94 GHz) measurements were carried out on a Bruker (Karlsruhe, Germany) E680 spectrometer.…”

Section: Purification Of Active Mcrmentioning

confidence: 99%

Coordination and binding geometry of methyl-coenzyme M in the red1m state of methyl-coenzyme M reductase

et al. 2008

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Methane formation in methanogenic Archaea is catalyzed by methyl-coenzyme M reductase (MCR) and takes place via the reduction of methyl-coenzyme M (CH 3 -S-CoM) with coenzyme B (HS-CoB) to methane and the heterodisulfide CoM-S-S-CoB. MCR harbors the nickel porphyrinoid coenzyme F 430 as a prosthetic group, which has to be in the Ni(I) oxidation state for the enzyme to be active. To date no intermediates in the catalytic cycle of MCR red1 (red for reduced Ni) have been identified. Here, we report a detailed characterization of MCR red1m (''m'' for methyl-coenzyme M), which is the complex of MCR red1a (''a'' for absence of substrate) with CH 3 -S-CoM. Using continuous-wave and pulse electron paramagnetic resonance spectroscopy in combination with selective isotope labeling ( 13 C and 2 H) of CH 3 -S-CoM, it is shown that CH 3 -S-CoM binds in the active site of MCR such that its thioether sulfur is weakly coordinated to the Ni(I) of F 430 . The complex is stable until the addition of the second substrate, HS-CoB. Results from EPR spectroscopy, along with quantum mechanical calculations, are used to characterize the electronic and geometric structure of this complex, which can be regarded as the first intermediate in the catalytic mechanism.

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“…[11] The spectrum measured close to g k (trace a) consists of a doublet centered at 30 MHz with the two peaks split by twice the 14 N Larmor frequency, 2n N = 7.2 MHz. Consequently, these two peaks are assigned to strongly coupled nitrogens with a hyperfine coupling of 60 MHz and an unresolved nuclear quadrupole interaction along this orientation.…”

mentioning

confidence: 99%

Asymmetric Spin Density Distribution in the Copper(II) Complex of N‐Confused Tetraphenylporphyrin: A Multifrequency Continuous‐Wave and Pulse EPR Study

Mitrikas¹,

Calle²,

Schweiger³

2005

Angew Chem Int Ed

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The magnetic interactions between the unpaired electron and the nitrogen donors of the porphyrin ring in the copper(II) complex of N‐confused tetraphenylporphyrin, [CuII(nctpp)], were studied by continuous‐wave (cw) and pulse EPR methods (see picture). A pronounced asymmetric distribution of the spin density on the three core nitrogen nuclei was found, in contrast to the spin density distribution in the symmetric [CuII(tpp)] complex.

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A Q-Band Pulse EPR/ENDOR Spectrometer and the Implementation of Advanced One- and Two-Dimensional Pulse EPR Methodology

Cited by 81 publications

References 27 publications

Distance determination from dysprosium induced relaxation enhancement: a case study on membrane-inserted WALP23 polypeptides

Distance determination from dysprosium induced relaxation enhancement: a case study on membrane-inserted WALP23 polypeptides

Coordination and binding geometry of methyl-coenzyme M in the red1m state of methyl-coenzyme M reductase

Asymmetric Spin Density Distribution in the Copper(II) Complex of N‐Confused Tetraphenylporphyrin: A Multifrequency Continuous‐Wave and Pulse EPR Study

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