Calculation of the Exact Axial EPR Resonance Fields for Spin S=2

Baranowski, J.; Cukierda, T.; Jeżowska‐Trzebiatowska, B.

doi:10.1007/978-3-642-81344-3_252

Cited by 9 publications

(19 citation statements)

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“…The S ¼ 1 spectrum can have no more than three transitions, and these transitions are often significantly broadened by D-strain, to give a rather featureless spectrum. Third, the assignment of features to the S ¼ 2 spin manifold has relied on spectral diagrams calculated for axial symmetry [49], which likely do not apply to most Mn(II) proteins and model complexes. In addition, the diagrams predict only line positions and thus the analyses ignore relative intensity information.…”

Section: Discussionmentioning

confidence: 99%

Quantitative analysis of dinuclear manganese(II) EPR spectra

Golombek

Hendrich

2003

Journal of Magnetic Resonance

103

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Section: Discussionmentioning

confidence: 99%

Quantitative analysis of dinuclear manganese(II) EPR spectra

Golombek

Hendrich

2003

Journal of Magnetic Resonance

103

View full text Add to dashboard Cite

“…The ZFS is not linearly related to the spectral splitting but must be obtained by spectral simulation or by fitting to the expression for transition frequencies. We adopted the latter procedure, using the convenient spectral diagrams derived for the case of axial ZFS (Baranowski et al, 1979;DeVore et al, 1978 Weltner, 1981). These diagrams give the positions of the EPR transitions for a system of randomly oriented particles of known spin.…”

Section: Discussionmentioning

confidence: 99%

“…Our approach is illustrated in Figure 7 which compares the EPR spectrum of compound 1 to the predicted transitions at the parallel (solid lines) and perpendicular turning points (dashed lines) for a randomly oriented quintet spin state as a function of D-rfhv (Baranowski et al, 1979). The horizontal dashed line is drawn at D2 = 0.056 cm-1 where it intersects the resonance magnetic field positions in close correspondence with the turning points observed in the experimental spectrum (Figure 7, bottom).…”

Section: Discussionmentioning

confidence: 99%

Determination of the Metal Ion Separation and Energies of the Three Lowest Electronic States of Dimanganese(II,II) Complexes and Enzymes: Catalase and Liver Arginase

et al. 1995

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The dimanganese (II,II) catalase from Thermus thermophilus, MnCat(II,II), arginase from rat liver, Arg(II,II), and several dimanganese(II,II) compounds, LMn2XY2, which are functional catalase mimics, all possess a pair of coupled Mn(II) ions in their catalytic sites. For each of these, we have measured by EPR spectroscopy the relative energies separating the three lowest electronic states (singlet, triplet, and quintet), described a general method for extracting the individual spectra for these states by multicomponent analysis, and determined the Mn-Mn separation. The triplet-singlet and quintet-singlet energy gaps were modeled well by fitting the temperature dependence of the EPR intensities to a Boltzmann expression for a pair of Mn(II) ions coupled by isotropic Heisenberg spin exchange (-2JS1S2). This dependence indicates diamagnetic ground states with delta E10 (cm-1) = magnitude of 2J = 4 and 11.2 cm-1 for Arg-(II,II)(+borate) and MnCat(II,II)(phosphate), respectively. This large difference in magnitude of 2J reflects either a difference in the bridging ligands or, possibly, a weaker ligand field (larger ionization potential) for the Mn(II) ions in arginase. In n-butanol/CH2Cl2 the triplet-singlet energy gaps for [LMn2(CH3CO2)](C1O4)2 (1), [LMn2(CH3CO2)3] (2), and [LMn2Cl3] (3), where HL = N,N,N',N'-tetrakis(2-methylenebenzimidazole)-1,3-diaminopropan+ ++-2-ol, are 23-24 cm-1. Comparison of the Heisenberg exchange interaction constants for more than 30 dimanganese(II,II) complexes suggests a possible bridging structure of (mu-OH)(mu-carboxylate)1-2 for MnCat(II,II), while the 3-fold weaker coupling in Arg(II,II) suggests mu-aqua in place of mu-hydroxide. EPR spectra of both the triplet and quintet electronic states were extracted and found to exhibit zero-field splittings (ZFS) and resolved 55Mn hyperfine splittings indicating spin-coupled Mn2-(II,II) species. The major ZFS interaction could be attributed to the magnetic dipole-dipole interaction between the Mn(II) ions. A linear correlation is observed between the crystallographically determined Mn-Mn distance and the ZFS of the quintet state (D2) for five dimanganese pairs for which both data sets are available. Using this correlation, the Mn-Mn distance in Arg(II,II) is predicted to be 3.36-3.57 A for the native enzyme (multiple forms) and 3.59 A for MnCat(II,II)(phosphate). Addition of the inhibitor borate to Arg(II,II) simplifies the ZFS, indicative of conversion to a single species with mean Mn-Mn separation of 3.50 A. The second metal ion in dinuclear complexes possessing a shared bridging ligand has been shown to attenuate the strength of the mu-ligand field potential, as monitored by the strength of the single ion ZFS.(ABSTRACT TRUNCATED AT 250 WORDS)

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“…Thus the contribution to the resonances at 289 and 430 mT from the triplet S=1 state must be very small. The positions of these quintet state resonances has been shown to be a function of the zero-field splitting of that state, D2, 41 (Fig. 6b).…”

Section: Epr Spectroscopy Of Mn(ii)-substituted Ecmetap-imentioning

confidence: 98%

Characterization of the active site and insight into the binding mode of the anti-angiogenesis agent fumagillin to the manganese(II)-loaded methionyl aminopeptidase from Escherichia coli

et al. 2004

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EPR spectra were recorded for methionine aminopeptidase from Escherichia coli (EcMetAP-I) samples (approximately 2.5 mM) to which one and two equivalents of Mn(II) were added (the latter is referred to as [MnMn(EcMetAP-I)]). The spectra for each sample were indistinguishable except that the spectrum of [MnMn(EcMetAP-I)] was twice as intense. The EPR spectrum of [MnMn(EcMetAP-I)] exhibited the characteristic six-line g approximately 2 EPR signal of mononuclear Mn(II) with A(av)((55)Mn)=9.3 mT (93 G) and exhibited Curie-law temperature dependence. This signal is typical of Mn(II) in a ligand sphere comprising oxygen and/or nitrogen atoms. Other features in the spectrum were observed only as the temperature was raised from that of liquid helium. The temperature dependences of these features are consistent with their assignment to excited state transitions in the S=1, 2 ... 5 non-Kramer's doublets, due to two antiferromagnetically coupled Mn(II) ions with an S=0 ground state. This assignment is supported by the observation of a characteristic 4.5 mT hyperfine pattern, and by the presence of signals in the parallel mode consistent with a non-Kramers' spin ladder. Upon the addition of the anti-angiogenesis agent fumagillin to [MnMn(EcMetAP-I)], very small changes were observed in the EPR spectrum. MALDI-TOF mass spectrometry indicated that fumagillin was, however, covalently coordinated to EcMetAP-I. Therefore, the inhibitory action of this anti-angiogenesis agent on EcMetAP-I appears to involve covalent binding to a polypeptide component at or near the active site rather than direct binding to the metal ions.

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Calculation of the Exact Axial EPR Resonance Fields for Spin S=2

Cited by 9 publications

References 0 publications

Quantitative analysis of dinuclear manganese(II) EPR spectra

Quantitative analysis of dinuclear manganese(II) EPR spectra

Determination of the Metal Ion Separation and Energies of the Three Lowest Electronic States of Dimanganese(II,II) Complexes and Enzymes: Catalase and Liver Arginase

Characterization of the active site and insight into the binding mode of the anti-angiogenesis agent fumagillin to the manganese(II)-loaded methionyl aminopeptidase from Escherichia coli

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