Photoselection studies on the orientation of chlorophyll a"I in the functional membrane of photosynthesis

Junge, W. ; Eckhof, A.

Amsterdam : Elsevier
ISSN:
0005-2728
Source:
Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
Topics:
Biology
Chemistry and Pharmacology
Medicine
Physics
Type of Medium:
Electronic Resource
URL:
_version_ 1798292363125194752
autor Junge, W.
Eckhof, A.
autorsonst Junge, W.
Eckhof, A.
book_url http://linkinghub.elsevier.com/retrieve/pii/0005-2728(74)90116-9
datenlieferant nat_lic_papers
fussnote The orientation of chlorophyll a"I in the functional membrane of photosynthesis in green plants is studied by a photoselection technique. On excitation of an isotropic suspension of isolated spinach chloroplasts with a linearly polarized flash of light linear dichroism of the absorption changes of chlorophyll a"I (wavelengths 705 and 430 nm) is observed. The dichroism is maximum for excitation at wavelengths greater than 690 nm, medium at excitation into the blue band of the chloroplast absorption spectrum, and it is small if excitation goes into all red transition moments above 600 nm. This reflects the degree of order between the transition moments of the antennae system around Photosystem I. We conclude as to a higher order between the transition moments at the long-wavelength end of the spectrum in comparison with a lower degree of order between the transition moments belonging to the intervall from 600 to 680 nm. This confirms the results of other authors which were obtained with oriented chloroplasts. However, the photoselection approach avoids characteristic artifacts which may affect linear-dichroism studies with oriented membranes.A quantitative interpretation of the observed photoinduced dichroism of chlorophyll a"I to yield the orientation of the respective porphyrin rings in the membrane is not feasible yet due to the absence of specific information on the symmetry properties of the antennae system and on the geometry of the chlorophyll a"I aggregate. Under the assumption of a circular degenerate antennae system a rather flat inclination of chlorophyll a"I has to be expected.
hauptsatz hsatz_simple
identnr NLZ185654762
issn 0005-2728
journal_name Biochimica et Biophysica Acta (BBA)/Bioenergetics
materialart 1
package_name Elsevier
publikationsort Amsterdam
publisher Elsevier
reference 357 (1974), S. 103-117
search_space articles
shingle_author_1 Junge, W.
Eckhof, A.
shingle_author_2 Junge, W.
Eckhof, A.
shingle_author_3 Junge, W.
Eckhof, A.
shingle_author_4 Junge, W.
Eckhof, A.
shingle_catch_all_1 Junge, W.
Eckhof, A.
Photoselection studies on the orientation of chlorophyll a"I in the functional membrane of photosynthesis
0005-2728
00052728
Elsevier
shingle_catch_all_2 Junge, W.
Eckhof, A.
Photoselection studies on the orientation of chlorophyll a"I in the functional membrane of photosynthesis
0005-2728
00052728
Elsevier
shingle_catch_all_3 Junge, W.
Eckhof, A.
Photoselection studies on the orientation of chlorophyll a"I in the functional membrane of photosynthesis
0005-2728
00052728
Elsevier
shingle_catch_all_4 Junge, W.
Eckhof, A.
Photoselection studies on the orientation of chlorophyll a"I in the functional membrane of photosynthesis
0005-2728
00052728
Elsevier
shingle_title_1 Photoselection studies on the orientation of chlorophyll a"I in the functional membrane of photosynthesis
shingle_title_2 Photoselection studies on the orientation of chlorophyll a"I in the functional membrane of photosynthesis
shingle_title_3 Photoselection studies on the orientation of chlorophyll a"I in the functional membrane of photosynthesis
shingle_title_4 Photoselection studies on the orientation of chlorophyll a"I in the functional membrane of photosynthesis
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geomar
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source_archive Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
timestamp 2024-05-06T08:47:20.006Z
titel Photoselection studies on the orientation of chlorophyll a"I in the functional membrane of photosynthesis
titel_suche Photoselection studies on the orientation of chlorophyll a"I in the functional membrane of photosynthesis
The orientation of chlorophyll a"I in the functional membrane of photosynthesis in green plants is studied by a photoselection technique. On excitation of an isotropic suspension of isolated spinach chloroplasts with a linearly polarized flash of light linear dichroism of the absorption changes of chlorophyll a"I (wavelengths 705 and 430 nm) is observed. The dichroism is maximum for excitation at wavelengths greater than 690 nm, medium at excitation into the blue band of the chloroplast absorption spectrum, and it is small if excitation goes into all red transition moments above 600 nm. This reflects the degree of order between the transition moments of the antennae system around Photosystem I. We conclude as to a higher order between the transition moments at the long-wavelength end of the spectrum in comparison with a lower degree of order between the transition moments belonging to the intervall from 600 to 680 nm. This confirms the results of other authors which were obtained with oriented chloroplasts. However, the photoselection approach avoids characteristic artifacts which may affect linear-dichroism studies with oriented membranes.A quantitative interpretation of the observed photoinduced dichroism of chlorophyll a"I to yield the orientation of the respective porphyrin rings in the membrane is not feasible yet due to the absence of specific information on the symmetry properties of the antennae system and on the geometry of the chlorophyll a"I aggregate. Under the assumption of a circular degenerate antennae system a rather flat inclination of chlorophyll a"I has to be expected.
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