Exciton Chirality Method. Oriented Molecules ? Anisotropic Phases

Kuball, Hans‐Georg; Dorr, Elmar; Höfer, T.; Türk, Oliver

doi:10.1007/s00706-005-0282-2

Cited by 16 publications

(15 citation statements)

References 3 publications

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“…The total CD in randomly oriented samples (isotropic CD) is the sum of the contributions from the different anisotropic CD components (Kuball et al 1993(Kuball et al , 2005:…”

Section: Anisotropic Circular Dichroismmentioning

confidence: 99%

“…It follows that, for uniaxial samples, it is sufficient to measure the CD in isotropic and only one of the oriented positions, while the other can be calculated (Kuball et al 1993(Kuball et al , 2005:…”

Section: Anisotropic Circular Dichroismmentioning

confidence: 99%

“…It is well known, however, that CD also depends on the propagation direction of light with respect to the chiral molecule or oriented anisotropic phase (Schellman and Jensen 1987). The CD measured on molecules with fixed orientation, termed anisotropic CD (ACD), reveals additional, independent information about the system under investigation that is not available in the isotropic CD (CD iso ) spectrum (Kuball 2002;Kuball et al 1993Kuball et al , 2005Kuball and Höfer 2000a, b). ACD of oriented molecules can yield information about their molecular configuration and chirality.…”

Section: Introductionmentioning

confidence: 99%

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Anisotropic circular dichroism signatures of oriented thylakoid membranes and lamellar aggregates of LHCII

et al. 2011

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In photosynthesis research, circular dichroism (CD) spectroscopy is an indispensable tool to probe molecular architecture at virtually all levels of structural complexity. At the molecular level, the chirality of the molecule results in intrinsic CD; pigment-pigment interactions in protein complexes and small aggregates can give rise to excitonic CD bands, while "psi-type" CD signals originate from large, densely packed chiral aggregates. It has been well established that anisotropic CD (ACD), measured on samples with defined non-random orientation relative to the propagation of the measuring beam, carries specific information on the architecture of molecules or molecular macroassemblies. However, ACD is usually combined with linear dichroism and can be distorted by instrumental imperfections, which given the strong anisotropic nature of photosynthetic membranes and complexes, might be the reason why ACD is rarely studied in photosynthesis research. In this study, we present ACD spectra, corrected for linear dichroism, of isolated intact thylakoid membranes of granal chloroplasts, washed unstacked thylakoid membranes, photosystem II (PSII) membranes (BBY particles), grana patches, and tightly stacked lamellar macroaggregates of the main light-harvesting complex of PSII (LHCII). We show that the ACD spectra of face- and edge-aligned stacked thylakoid membranes and LHCII lamellae exhibit profound differences in their psi-type CD bands. Marked differences are also seen in the excitonic CD of BBY and washed thylakoid membranes. Magnetic CD (MCD) spectra on random and aligned samples, and the largely invariable nature of the MCD spectra, despite dramatic variations in the measured isotropic and anisotropic CD, testify that ACD can be measured without substantial distortions and thus employed to extract detailed information on the (supra)molecular organization of photosynthetic complexes. An example is provided showing the ability of CD data to indicate such an organization, leading to the discovery of a novel crystalline structure in macroaggregates of LHCII.

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“…The total CD in randomly oriented samples (isotropic CD) is the sum of the contributions from the different anisotropic CD components (Kuball et al 1993(Kuball et al , 2005:…”

Section: Anisotropic Circular Dichroismmentioning

confidence: 99%

Section: Anisotropic Circular Dichroismmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Anisotropic circular dichroism signatures of oriented thylakoid membranes and lamellar aggregates of LHCII

et al. 2011

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show abstract

“…However, a significant limitation of this approach can occur in systems undergoing conformational changes and in applications to acyclic compounds. The flexibility of such systems may cause difficulties in the correct stereochemical assignment [21][22][23].…”

Section: Introductionmentioning

confidence: 99%

Complementarity of electronic and vibrational circular dichroism based on stereochemical studies of vic-diols

Jawiczuk

Górecki

Masnyk

et al. 2015

TrAC Trends in Analytical Chemistry

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“…These limitations can be overcome theoretically by measuring the anisotropic CD (ACD), i.e. the CD of molecules with fixed macroscopic space orientation [67,68]. For example, in an ideal case, by measuring the CD of the dimer separately with light propagating along the x and y coordinate axes, one could extract the individual exciton CD bands [69] and hence obtain direct physical parameters, such as the orientation of the excitonic transition dipole moments or the coupling energy (from the difference in the bands' central frequencies), which are not accessible from ordinary CD measurements.…”

Section: Excitonic Circular Dichroismmentioning

confidence: 99%

Excitonic States and Excitation Energy Transfer in Plant Light-Harvesting Complexes in Different Molecular Environments

Akhtar¹

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Exciton Chirality Method. Oriented Molecules ? Anisotropic Phases

Cited by 16 publications

References 3 publications

Anisotropic circular dichroism signatures of oriented thylakoid membranes and lamellar aggregates of LHCII

Anisotropic circular dichroism signatures of oriented thylakoid membranes and lamellar aggregates of LHCII

Complementarity of electronic and vibrational circular dichroism based on stereochemical studies of vic-diols

Excitonic States and Excitation Energy Transfer in Plant Light-Harvesting Complexes in Different Molecular Environments

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