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- Fragata, M., et al.
(författare)
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Linear Dichroism (250-700 nm) of Chlorophyll a and Pheophytin a Oriented in a Lamellar Phase of Glycerylmonooctanoate / H2O. Characterization of Electronic Transitions
- 1988
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Ingår i: Photochemistry and Photobiology. - : Wiley. - 0031-8655 .- 1751-1097. ; 47:1, s. 133-143
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Tidskriftsartikel (refereegranskat)abstract
- We determined the polarized and isotropic visible/UV absorption spectra of chlorophyll a (Chi a) and pheophytin a (Pheo a) oriented in the lamellar phase of glycerylmonooctanoate/H2O. Resolution into mutually perpendicular X- and Y-polarized absorption spectra of the pigments was achieved assuming that the transition moments of Chi a and Pheo a are located in the plane of the chromophores. The polarized spectra were deconvoluted into harmonic progressions and the resultant assignment of band positions in the long-wavelength region was found to correlate well with independent spectral measurements, such as the polarisation of fluorescence. However, the correlation of the experimentally determined transitions with the results of theoretical calculations is not straightforward. The overall conclusions are of fundamental interest in the determination of orientations of the tetrapyrrole macrocycle in lipid lamellae and pigment-protein structures of photosynthetic membranes.
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| 5. |
- Nordén, Bengt, 1945, et al.
(författare)
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Nucleic acid-metal interactions. IV. Complexes of Ag(I) with thymine and cytosine from studies of UV and IR dichroic spectra
- 1986
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Ingår i: Journal of Crystallographic and Spectroscopic Research. - : Springer Science and Business Media LLC. - 0277-8068 .- 1572-8854. ; 16:2, s. 217-226
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Tidskriftsartikel (refereegranskat)abstract
- The linear dichroism of the complexes of thymine and cytosine with silver(I) ions dispersed in stretched polyvinylalcohol films was measured in the infrared and in the near ultraviolet regions of the spectrum. The infrared results were helpful in establishing the orientation of the complexes in the films; they also confirmed that the site of silver binding in the case of cytosine involves the carbonyl oxygen. The ultraviolet spectra were deconvoluted into separate electronic transitions and the corresponding transition moments of silver complexes were determined.
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| 6. |
- Nordén, Bengt, 1945, et al.
(författare)
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Nucleic acid–metal interactions: V. The effect of silver(I) on the structures of A- and B-DNA forms
- 1986
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Ingår i: Biopolymers. - : Wiley. - 0006-3525 .- 1097-0282. ; 25:8, s. 1531-1545
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Tidskriftsartikel (refereegranskat)abstract
- The interaction of silver(I) with DNA has been studied with uv LD in aqueous solution and in a humid anisotropic poly(vinyl alcohol) host (B-DNA) and also in 80% ethanolic solution (A-DNA). Addition of silver ions has a pronounced effect on the dichroic spectra of DNA, indicating that the DNA structure is significantly altered. By correlation with calculated reduced LD spectra, using intensities and moments of the corresponding electronic transitions of the DNA bases, the experimental spectra of DNA at high silver content may be interpreted in terms of tilt and roll angles of the bases in the double helix. In ethanolic A-DNA solution there is a pronounced decrease in the orientation by flow of DNA, suggesting that the complexation of DNA to silver may be accompanied by the formation of compact tertiary structures.
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