| | 1 | Author
| Ursula Lehmann-Kirk, KlausP. Bader, G. Eorg, H. Schmid, Alfons Radunz | Requires cookie* | | | Title
| Inhibition of Photosynthetic Electron Transport in Tobacco Chloroplasts and Thylakoids of the Blue Green Alga Oscillatoria chalybea by an Antiserum to Synthetic Zeaxanthin  | | | | Abstract
| An antiserum to synthetic Z eaxanthin inhibits photosynthetic electron transport on the oxygen-evolving side of photosystem II in tobacco chloroplasts and thylakoids o f the filamentous blue-green alga Oscillatoria chalybea. The inhibition site lies for both species between the site o f electron donation of water or tetramethyl benzidine and that o f diphenyl carbazide or manganese II ions. Typical photosystem I reactions are not impaired by the antiserum. The effect of the antiserum concerning the inhibition site is practically identical to that o f the earlier described antiserum to violaxanthin. However, the degree o f inhibition seems to be generally somewhat lower with the antiserum to Zeaxanthin, than with that to violaxanthin which hints at a lesser accessibility of ze-axanthin, in the tylakoid membrane in comparison to violaxanthin. In the course of these investigations new evidence was obtained that the oxygen-evolving side of the electron transport scheme is differently organized in Oscillatoria chalybea when compared to tobacco chloroplasts. Thus, the silicomolybdate reduction with water as the electron donor is sen sitive to DCMU in these algae. | | | |
Reference
| Z. Naturforsch. 34c, 1218—1221 (1979); received August 2 1979 | | | |
Published
| 1979 | | | |
Keywords
| Antibodies, Oxygen-Evolving Side, Xanthophylls, Chloroplasts, Blue-Green Algae | | | |
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| default:Reihe_C/34/ZNC-1979-34c-1218.pdf | | | | Identifier
| ZNC-1979-34c-1218 | | | | Volume
| 34 | |
| 3 | Author
| SeymourSteven Brody | Requires cookie* | | | Title
| Temperature Induced Changes in the Absorption Spectra of Porphyridium cruentum and Anacystis nidulans | | | | Abstract
| Cooling A. nidulans or P. cruentum from 26 °C to 4 °C results in progressive spectral changes. The most significant changes are increases in absorbance at 690 nm (photosystem II), 678 nm (antenna chlorophyll), 625 nm (phycocyanin), and 505 nm (electrochromic band). In the case o f P. cruentum there are also increases in absorbance at 568 and 545 nm (B-phycoerythrin) and a decrease at 587 nm. The spectral changes in both organisms are accompanied by decreases at 703 nm (photosystem I or aggregated chlorophyll), 650 nm (allophycocyanin) and 486 nm (carotenoid). Heating A. nidulans or P. cruentum from 4 °C to 44 °C results in increases in absorbance at 705 nm (photosystem I) and 486 nm (carotenoid), accompanied by decreases at 690 nm (photo system II), 676 nm (antenna chlorophyll), 628 nm (phycocyanin), 507 nm (electrochromic band) and 469 nm (carotenoid). In the case o f P. cruentum there are also decreases at 568 and 546 nm (B-phycoerythrin) and an increase at 587 nm. The possible origin o f the spectral change at 587 nm. The possible origin o f the spectral change at 587 nm is discussed. The spectral changes o f the chlorophyll bands (703, 690, 678 nm) and the electrochromic band (502 nm) are associated with phase changes of the lipid membrane. Lowering the temperature results in a decrease o f aggregated chlorophyll or photosystem I, and vice versa. These spectral changes are also observed in green chloroplasts. The spectral changes o f the phycobilins may originate from a temperature dependent change of the ion balance o f the thylakoid. A spectral change may result from the ensuring modification of the stacking or from an electrochromic effect. | | | |
Reference
| Z. Naturforsch. 36c, 1013—1020 (1981); received September 141981 | | | |
Published
| 1981 | | | |
Keywords
| Photosynthesis, Lipid Phase Transition, Blue-Green Algae, Red Algae, Change in Absorption, Phycobili Proteins, Chlorophyll | | | |
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| default:Reihe_C/36/ZNC-1981-36c-1013.pdf | | | | Identifier
| ZNC-1981-36c-1013 | | | | Volume
| 36 | |
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