Linear and Circular Dichroism

Garab, Győző

doi:10.1007/0-306-47960-5_2

Cited by 31 publications

(38 citation statements)

References 133 publications

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“…Evidently, absence of long-range order (below and above the optimal conclusion that CD bands at (0)493 and (0)682 nm are related to the long-range chiral order in the aggregates detergent concentrations) renders DCD impossible. On the other hand, in tightly stacked lamellar aggregates, (for a recent review, see 24). These examples of large aggregates clearly show that macroaggregation of rigidity of the chiral macrostructure may hinder the structural flexibility.…”

Section: Electron Microscopy Dependence Of Macrostructure Of Lhcii Agmentioning

confidence: 96%

Isolation of Lamellar Aggregates of the Light-Harvesting Chlorophyll a/b Protein Complex of Photosystem II with Long-Range Chiral Order and Structural Flexibility

Simidjiev

Barzda

Mustárdy

et al. 1997

Analytical Biochemistry

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Section: Electron Microscopy Dependence Of Macrostructure Of Lhcii Agmentioning

confidence: 96%

Isolation of Lamellar Aggregates of the Light-Harvesting Chlorophyll a/b Protein Complex of Photosystem II with Long-Range Chiral Order and Structural Flexibility

Simidjiev

Barzda

Mustárdy

et al. 1997

Analytical Biochemistry

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“…temperature or pH. In plants, CD spectroscopy in the visible range originates from pigment-pigment interactions and hence is a valuable tool for probing the molecular architecture of the photosynthetic complexes and supercomplexes and their macroorganization in the membrane system (Garab, 1996;Garab and van Amerongen, 2009). CD can originate from different levels of complexity in the sample.…”

Section: Velikova Et Almentioning

confidence: 99%

Increased Thermostability of Thylakoid Membranes in Isoprene-Emitting Leaves Probed with Three Biophysical Techniques

et al. 2011

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Three biophysical approaches were used to get insight into increased thermostability of thylakoid membranes in isoprene-emittingplants.Arabidopsis (Arabidopsis thaliana) plants genetically modified to make isoprene and Platanus orientalis leaves, in which isoprene emission was chemically inhibited, were used. First, in the circular dichroism spectrum the transition temperature of the main band at 694 nm was higher in the presence of isoprene, indicating that the heat stability of chiral macrodomains of chloroplast membranes, and specifically the stability of ordered arrays of light-harvesting complex IIphotosystem II in the stacked region of the thylakoid grana, was improved in the presence of isoprene. Second, the decay of electrochromic absorbance changes resulting from the electric field component of the proton motive force (DA 515 ) was evaluated following single-turnover saturating flashes. The decay of DA 515 was faster in the absence of isoprene when leaves of Arabidopsis and Platanus were exposed to high temperature, indicating that isoprene protects the thylakoid membranes against leakiness at elevated temperature. Finally, thermoluminescence measurements revealed that S 2 Q B 2 charge recombination was shifted to higher temperature in Arabidopsis and Platanus plants in the presence of isoprene, indicating higher activation energy for S 2 Q B 2 redox pair, which enables isoprene-emitting plants to perform efficient primary photochemistry of photosystem II even at higher temperatures. The data provide biophysical evidence that isoprene improves the integrity and functionality of the thylakoid membranes at high temperature. These results contribute to our understanding of isoprene mechanism of action in plant protection against environmental stresses.

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“…Chloroplasts, for instance, can be readily aligned with field strengths of about 10 V cm À1 (Gagliano et al 1977). Submicroscopic particles (such as isolated photosystems, or viruses) may require a field 1-2 orders of magnitude higher (van Haeringen et al 1994;Garab 1996).…”

Section: Resultsmentioning

confidence: 99%

“…This differential scattering originates from the long-range chiral order of the chromophores (Garab et al 1988b). As pointed out in a theory for the so-called psi-type aggregates, such as chromosomes and other DNA condensates (Keller and Bustamante 1986;Tinoco et al 1987), valid also for LHCII-containing macrodomains (Garab 1996), the interaction of chromophores with light involves long-range coupling interactions, corresponding to internal scattering and intermediate term interaction. These are known to give rise to ''anomalous'' spectroscopic and very strong local, microscopic circular dichroism features, as indeed observed in chloroplasts (Finzi et al 1989).…”

mentioning

confidence: 97%

“…However, birefringence in these particles, which constitute the chloroplast, can be large. Strong birefringence and dichroism of all photosynthetic membranes originate mainly from the intrinsic, inherently anisotropic molecular architecture of the pigment-protein complexes and supercomplexes, and their ordered arrays in the membrane (Breton and Vermeglio 1982;Garab 1996;Boekema et al 2000). It has also been well established that in photosynthetic membranes the contribution of form or shape birefringence is small (Sauer and Calvin 1962).…”

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confidence: 99%

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Alignment of biological microparticles by a polarized laser beam

et al. 2005

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The optical alignment of biological samples is of great relevance to microspectrometry and to the micromanipulation of single particles. Recently, Bayoudh et al. (J. Mod. Opt. 50:1581-1590 have shown that isolated, disk-shaped chloroplasts can be aligned in a controlled manner using an in-plane-polarized Gaussian beam trap, and suggested that this is due to their nonspherical shape. Here we demonstrate that the orientation of various micrometer-sized isolated biological particles, trapped by optical tweezers, can be altered in a controlled way by changing the plane of linear polarization of the tweezers. In addition to chloroplasts, we show that subchloroplast particles of small size and irregular overall shape, aggregated photosynthetic lightharvesting protein complexes as well as chromosomes can be oriented with the linearly polarized beam of the tweezers. By using a laser scanning confocal microscope equipped with a differential polarization attachment, we also measured the birefringence of magnetically oriented granal chloroplasts, and found that they exhibit strong birefringence with large local variations, which appears to originate from stacked membranes. The size and sign of the birefringence are such that the resulting anisotropic interaction with the linearly polarized laser beam significantly contributes to the torque orienting the chloroplasts.

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Linear and Circular Dichroism

Cited by 31 publications

References 133 publications

Isolation of Lamellar Aggregates of the Light-Harvesting Chlorophyll a/b Protein Complex of Photosystem II with Long-Range Chiral Order and Structural Flexibility

Isolation of Lamellar Aggregates of the Light-Harvesting Chlorophyll a/b Protein Complex of Photosystem II with Long-Range Chiral Order and Structural Flexibility

Increased Thermostability of Thylakoid Membranes in Isoprene-Emitting Leaves Probed with Three Biophysical Techniques

Alignment of biological microparticles by a polarized laser beam

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