| | 2 | Author
| Alfred Hissung, Clemens Von Sonntag | Requires cookie* | | | Title
| Radiolysis of Cytosine, 5-Methyl Cytosine and 2'-Deoxycytidine in Deoxygenated Aqueous Solution A Pulse Spectroscopic and Pulse Conductometric Study of the OH Adduct  | | | | Abstract
| Using the pulse radiolysis technique the OH adducts of cytosine, 5-methyl cytosine and 2'-deoxycytidine were investigated in alkaline N20 saturated aqueous solutions. Ab-sorption spectra were recorded and their change with time was correlated with the change in conductivity. An OH -induced reaction (1.4 • 10 8 1 • mol -1 • s -1) was observed with OH adducts of cytosine and 5-methyl cytosine leading to radicals (pK = 10.3), the G-values of which were 3.2 and 1.6 respectively (conductivity measurements). These intermediates were assigned to the C-5 OH radical adducts. After completion of the free radical reactions (2k = 6 • 10 8 1 • mol -1 • s -1) the resulting product mixture showed pK-values of 8.3 (cytosine, G = 0.6), 10.5 (5-methyl cytosine, G = 0.8), 10.7 (cytosine, G=1.5; 2'-deoxycytidine, G=1.5) and 12.4 (cytosine, no G-value, determinable with optical detection). Ammonia, which is a product measured after y-radiolysis of all the three compounds investigated (G(NHs) = 0.6 ± 0.1), is not released within 15 ms after the pulse. | | | |
Reference
| Z. Naturforsch. 33b, 321—328 (1978); received November 25 1977 | | | |
Published
| 1978 | | | |
Keywords
| Cytosine, G-Values, pK-Values, Absorption Spectra, Pulse Radiolysis | | | |
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| | | | | TEI-XML for
| default:Reihe_B/33/ZNB-1978-33b-0321.pdf | | | | Identifier
| ZNB-1978-33b-0321 | | | | Volume
| 33 | |
| 3 | Author
| PaavoH. Hynninen | Requires cookie* | | | Title
| Electron Donor-Acceptor Properties of 10(S)-Chlorophyll a | | | | Abstract
| Evidence for the self-aggregation o f 10(S)-chlorophyll a (= chlorophyll a') in nonpolar solvents has been obtained by means o f absorption spectroscopy in the visible and infrared regions. The visible absorption spectrum of chlorophyll a' exhibits a shoulder at 680 nm in aliphatic hydrocar bon solvents and the infrared spectrum measured in carbon tetrachloride contains an "aggrega tion peak" at 1650 cm "1. IR spectroscopy shows, in addition, that the C-10 epim ers o f chlorophyll a are both present as monom ers in tetrahydrofuran. H ow ever, in the presence of a small amount o f aliphatic alcohol or water, the IR spectrum in tetrahydrofuran at lowered tem peratures exhibits an intense, wide absorption band at ~ 1650 cm -1 which was interpreted as arising from the hydrogen bonding o f the hydroxyl group to the C-9 keto carbonyl o f the chlorophyll. | | | |
Reference
| Z. Naturforsch. 39b, 675 (1984); received July 12 1983 | | | |
Published
| 1984 | | | |
Keywords
| Chlorophyll Epim ers, Chlorophyll Organization, Stereochem istry, Photosynthesis, Infrared Spectra, Absorption Spectra | | | |
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| default:Reihe_B/39/ZNB-1984-39b-0675.pdf | | | | Identifier
| ZNB-1984-39b-0675 | | | | Volume
| 39 | |
| 4 | Author
| Günter Döhler, Jean-Claude Leclerc, M. | Requires cookie* | | | Title
| Photosynthetic Adaptation in Synechococcus Cells | | | | Abstract
| The cyanobacterium Synechococcus (Anacystis nidulans, strain L 1401-1) grown under different light conditions showed variations in pigmentation. Ratios of photosynthetic pigments and the effect on quantum requirement and oxygen evolution were studied. An increase in the ratio of chlorophyll a forms with absorption maxima in the far red regime to total chlorophyll a forms was observed in cells grown in strong white light. The quantum efficiency of orange light (637 nm) -absorbed by phycocyanin — was higher after growth of Synechococcus in white than | | | |
Reference
| Z. Naturforsch. 37c, 1075—1080 (1982); received August 12 1982 | | | |
Published
| 1982 | | | |
Keywords
| Pigmentation, Quantum Requirement, Absorption Spectra, Oxygen Evolution, P 700, Synecho coccus | | | |
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| default:Reihe_C/37/ZNC-1982-37c-1075.pdf | | | | Identifier
| ZNC-1982-37c-1075 | | | | Volume
| 37 | |
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