M.C.D./M.C.P.L. saturation theory with application to molecules inD∞hand its subgroups

Schatz, P. N.; Mowery, Robert L.; Krausz, Elmars

doi:10.1080/00268977800101151

Cited by 79 publications

(46 citation statements)

References 13 publications

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“…The data were recalculated as plots of MCD intensity vs PB/2kT, where p is the Bohr magneton, B is the magnetic flux density, k is the Boltzmann constant, and Tis the absolute temperature. The theoretical MCD saturation expressions for allowed electronic transitions in axial molecules (Schatz et al, 1978) were used with the extensions of Thomson and Johnson (1980) for molecules with rhombic symmetry and the S = ground state. The parameters m, and m,, quoted in the theoretical magnetization data, are measures of the polarization of the transitions and refer to the transition dipole moments along z axis and in the x,y plane for an axial chromophore, respectively.…”

Section: Methodsmentioning

confidence: 99%

“…Orbital degeneracy in the ground state of the heme complexes results in Faraday C terms in the MCD spectrum that have an intensity dependent on both the temperature and magnetic field (Schatz et al, 1978). Comparison of the MCD spectral intensities of Fe(II1) and Fe(1V) species of HRP with the photolysis product indicates that the strong temperature dependence of the photochemical product closely resembles the strong temperature dependence that is observed in the Fe(II1) native HRP and low-spin alkaline HRP spectra rather than the weak HRP I and very weak HRP I1 temperature dependence.…”

Section: Bb/2ktmentioning

confidence: 99%

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Low-temperature magnetic circular dichroism studies of the photoreaction of horseradish peroxidase compound I

Gasyna¹,

Browett²,

Stillman³

1988

Biochemistry

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Horseradish peroxidase (HRP) compound I is photolabile at all temperatures between room temperature and 4 K. The photoredox reaction has been studied in frozen glassy solutions by using optical absorption and magnetic circular dichroism spectra following photolysis of HRP compound I with visible-wavelength light at 4.2 and 77 K. The photochemical process is characterized as a concerted two-electron transfer reaction which results in the conversion of the Fe(IV) heme pi-cation radical species of HRP compound I into a low-spin Fe(III) heme species. This reaction occurs even when photolysis is carried out at 4.2 K. Spectra recorded between 4.2 and 80 K for the low-spin ferric hydroxide complex of HRP closely resemble the data measured for the photochemical product. The proposed mechanism for the photoreaction is (formula; see text) No evidence is found for the formation of an Fe(II) heme at these temperatures.

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Section: Methodsmentioning

confidence: 99%

Section: Bb/2ktmentioning

confidence: 99%

Low-temperature magnetic circular dichroism studies of the photoreaction of horseradish peroxidase compound I

Gasyna¹,

Browett²,

Stillman³

1988

Biochemistry

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“…Energy (cm -1 ) properties, 10 for example in ferrous systems, which are often inaccessible to EPR spectroscopy. 11 In the previous section the terms contributing to an MCD transition have been discussed.…”

Section: Vtvh MCDmentioning

confidence: 99%

Magnetic Circular Dichroism of Paramagnetic Species

Solomon

Neidig

Schenk

2003

Comprehensive Coordination Chemistry II

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MCD spectroscopy combines the CD experiment with a longitudinal magnetic field, where the application of the magnetic field induces optical activity in any material so that all substances exhibit MCD activity. MCD probes the Zeeman splittings in the ground and excited states and the field-induced mixing between states. MCD intensity for a transition from a ground state |Ai to an excited state |Ji is given by Equation (1):for broadband transitions when the MCD intensity is linear with field. Here, ÁA is the fielddependent difference between left-and right-circularly polarized light (lcp and rcp, respectively) absorption, E ¼ h#, is the electric permeability, C is the concentration, l is the path length, n is 339

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“…As shown below, knowledge of the eigenvectors and eigenvalues of the low-lying singlets allows calculation of the temperature dependence of MCD intensity which, together with the predicted sign of the MCD band for one-electron transition of a given symmetry, make it possible to assign the near-infrared transitions. The sign of the MCD and its temperature behaviour can be predicted from modi®ed general expressions given by Schatz et al [27] for a molecule which has an arbitrary orientation with respect to an external magnetic ®eld:…”

Section: Theoretical Backgroundmentioning

confidence: 99%

Assignment of conformation-sensitive near-infrared bands in high-spin ferrous haemoproteins.

Oganesyan

Sharonov

1997

Theoretical Chemistry Accounts: Theory, Computation, and Modeli

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An assignment of the near-infrared bands in the 600±800 nm spectral region observed in magnetic circular dichroism (MCD) spectra of high-spin ferrous haemoproteins is presented. The assignment is based on a relative energy level scheme for iron d-electrons, a comparison of predicted and measured temperature dependences of MCD intensity, a sign of MCD bands and a group theoretical analysis of allowed transitions. The proposed assignment is consistent with the $15-nm red shift of the $760 nm band on breakage of the Fe-His bond in deoxy-myoglobin at low pH, with low-temperature photolysis experiments available for CO complexes of several haemoproteins. In accordance with the observations, the intensity of the MCD bands for proteins with a sulphur anion of cysteine as proximal haemligand (cytochrome P450 and chloroperoxidase) is predicted to be diminished by at least one order of magnitude compared to that for proteins with an imidazole of a histidine as a protein-derived haemligand (i.e. myoglobin, haemoglobin and horseradish peroxidase).

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M.C.D./M.C.P.L. saturation theory with application to molecules inD_∞hand its subgroups

Cited by 79 publications

References 13 publications

Low-temperature magnetic circular dichroism studies of the photoreaction of horseradish peroxidase compound I

Low-temperature magnetic circular dichroism studies of the photoreaction of horseradish peroxidase compound I

Magnetic Circular Dichroism of Paramagnetic Species

Assignment of conformation-sensitive near-infrared bands in high-spin ferrous haemoproteins.

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