| | 2 | Author
| R. En, C. Su, PetraD. Örrb, M. Artin, K. Ühnb, ClausK. Rieger0, M. Ikhael, Y. A. Ntip In D | Requires cookie* | | | Title
| Chiral Pool Synthesis of 4a-Substituted Carbocyclic Cyclopentanoid Nucleoside Precursors, I  | | | | Abstract
| A suitable protected D-ribono-1,4-lactone derivative has been used for the straightforward chiral pool synthesis of cyclopentanoid nucleoside precursors. Thus, epoxidation followed by deoxygenation or regioselective ring opening led to nucleoside precursors modified at the positions C(4), C(4a) and C(4,4a) as well as side-chain modified derivatives. The structures of the key intermediates were determined by X-ray analyses. | | | |
Reference
| Z. Naturforsch. 54b, 1068—1078 (1999); received May 21 1999 | | | |
Published
| 1999 | | | |
Keywords
| Nucleosides, Carbohydrates, X-Ray Data | | | |
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| default:Reihe_B/54/ZNB-1999-54b-1068.pdf | | | | Identifier
| ZNB-1999-54b-1068 | | | | Volume
| 54 | |
| 4 | Author
| BlahoslavM. Aršálek, Renata Rojíčková | Requires cookie* | | | Title
| Stress Factors Enhancing Production of Algal Exudates: a Potential Self-Protective Mechanism? | | | | Abstract
| Algae are known to produce extracellular organic substances under optimum conditions and increase their production under stress. The changes in amount and composition of extra cellular carbohydrates and proteins of three green algae Scenedesmus quadricauda, Chlorella kessleri and Raphidocelis subcapitata (known as Selenastrum capricornutum) were studied after a 5-days' cultivation under the influence of different types o f stress factors (osm otic, organic, and heavy metal stressors). NaCl enhanced the quantity of carbohydrates more than proteins. A higher increase o f proteins than carbohydrates was observed after addition of 3,5-dichlorophenol, glyphosate and cadmium chloride to algal cultures. The production of dissolved organic matter differs from species to species, with the age of a culture and the type of stressor. | | | |
Reference
| Z. Naturforsch. 51c, 646 (1996); received May 28/June 25. 1996 | | | |
Published
| 1996 | | | |
Keywords
| Algae, Extracellular Products, Proteins, Carbohydrates | | | |
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| default:Reihe_C/51/ZNC-1996-51c-0646.pdf | | | | Identifier
| ZNC-1996-51c-0646 | | | | Volume
| 51 | |
| 5 | Author
| Malle Mandre, Jaan Klõšeiko | Requires cookie* | | | Title
| Changing Carbohydrate Partitioning in 6-Year-Old Coniferous Trees after Prolonged Exposure to Cement Dust | | | | Abstract
| Two-year-old seedlings of Picea abies L., P. glauca L., P. mciriana L., Pinus sylvestris L. and Pseudotsuga menziesii L. were planted in a sample plot influenced by high concentrations of cement dust, and in an unpolluted (control) area in 1990. In 1994, the six-year-old trees were dug up in the pre-bud-break period. A comparative analysis of soluble sugars (glucose, fruc tose, sucrose, maltodextrines), starch and hemicelluloses contents was carried out and the changes in carbohydrate partitioning were estimated. A decrease in the total content of soluble sugars, mainly of glucose, fructose and maltodextrines, was observed in polluted trees, especially in roots, stems and buds, while the sucrose content increased in different organs. Fluctuations in glucose and fructose contents in roots were in good correlation with these sugars in needles and maltodextrines in stems and shoots. Changes in starch and hemicellu-lose partitioning between different organs of trees were modest and their directions were highly dependent on species. | | | |
Reference
| Z. Naturforsch. 52c, 586—594 (1997); received March 20/June 6 1997 | | | |
Published
| 1997 | | | |
Keywords
| Conifers, Dust Pollution, Carbohydrates, Partitioning | | | |
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| default:Reihe_C/52/ZNC-1997-52c-0586.pdf | | | | Identifier
| ZNC-1997-52c-0586 | | | | Volume
| 52 | |
| 6 | Author
| ClemensVon Sonntag, Miral Dizdaroglu, Dietrich Schulte-Frohlinde | Requires cookie* | | | Title
| y-Radiolysis of Cellobiose in N20-saturated Aqueous Solution Part II. Quantitative Measurements. Mechanisms of the Radical-induced Scission of the Glycosidic Linkage | | | | Abstract
| The y-radiolysis of cellobiose (10 -2 M) in N2O saturated aqueous solution has been investigated and the G-values of the following 21 products containing six or less C-atoms have been measured (G-values in parentheses): glucose (2.1), gluconic acid (0.70), 4-keto-glucose (0.07), 5-keto-glucose (0.05), 4-deoxy-glucose (0.27), 5-deoxy-gluconic acid (0.18), 2-deoxy-gluconic acid (0.13), 3-deoxy-4-keto-glucose (0.23), 2-deoxy-5-keto-glucose (0.34), 4-deoxy-5-keto-glucose (0.14), 6-deoxy-5-keto-glucose (0.02), arabinose (0.07), ribose (0.015), 2-deoxy-ribose (0.17), 3-deoxy-pentulose (0.01), erythrose (0.015), threose (0.015), 2-deoxy-tetrose (0.01), butanone-(2)-diol(1.4) (0.01), dihydroxyacetone (0.01), carbon monoxide (> 0.02). The formation of the major part (98%) of the measured products could be explained on the base of the following assumption: The first step of reaction sequence is abstraction of H atoms from C-H bonds of the cellobiose by OH radicals. Radicals at C-l', C-5' and C-4 and their successors undergo in a second step four types of reactions: hydrolysis, re-arrangement and H2O and CO elimination. In a third step the transformed radicals give rise to products by disproportionation reaction. Only two products out of 16 predicted under the above assumption are not observed. G-values for the attack at C-l', C-5' and C-4 are 1.4, 0.6 and 0.3 respectively. | | | |
Reference
| (Z. Naturforsch. 31b, 857—864 [1976]; received February 25 1976) | | | |
Published
| 1976 | | | |
Keywords
| Carbohydrates, Radical Reactions, y-Radiolysis, Cellobiose, Glycosidic Linkage | | | |
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| default:Reihe_B/31/ZNB-1976-31b-0857.pdf | | | | Identifier
| ZNB-1976-31b-0857 | | | | Volume
| 31 | |
| 7 | Author
| Heinz-Peter Schuchmann, Rita Wagner, Clemens Von Sonntag | Requires cookie* | | | Title
| 7-Radiolysis of 2'-Deoxycytidine-5'-phosphate in Deoxygenated Aqueous Solutions. OH Radical-Induced Alterations at the Sugar Moiety | | | | Abstract
| In order to elucidate some aspects of the mechanism of radical-induced strand break formation in DNA, the y-radiolysis of N20-saturated aqueous solutions of 2'-deoxycytidine-5'-phosphate has been studied as a model system. At pH 4 it has been observed that upon OH attack at the sugar moiety phosphate (G ^ 0.6) and cytosine (G = 1) are released and the following cytosine-free sugars are formed: 2,5-dideoxypentos-3,4-diulose, 1 (G = O.22), 2-deoxy-pentos-4-ulose, 2 (G = 0.1s), 2-deoxy-pentos-4-ulose-5-phosphate, 3 (G=0.06), 2-deoxypentonic acid-5-phosphate and its lactone, 5 (G «0.5). Some 2-deoxyribose-5-phosphate, 4 is also formed. Upon addition of H2O2 (up to 10 -2 M) prior to irradiation, G(l) is drastically reduced without giving rise to another cytosine-free product. G(3) increases at the expense of G(2). G (4 + 5) also increase upon H2O2 addition. The formation of these products and the change of their G values as a function of H2O2 concentration are discussed in the light of well-documented radical reactions of carbohydrates and related compounds. The precursor of 1 has been considered to be the radical at C-3', that of 2 and 3 the radical at C-4' and that of 5 the radical at C-l'. Product 4 is thought to arise from a radical-induced destruction of the cytosine moiety. These primary radicals which may undergo rearrangement, or eliminate phosphate, are readily oxidised by H202, a reaction which leads to the change of product distribution mentioned above. | | | |
Reference
| Z. Naturforsch. 38b, 1213—1220 (1983); received June 27 1983 | | | |
Published
| 1983 | | | |
Keywords
| Free Radicals, Radical Cations, Carbohydrates, DNA Model | | | |
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| default:Reihe_B/38/ZNB-1983-38b-1213.pdf | | | | Identifier
| ZNB-1983-38b-1213 | | | | Volume
| 38 | |
| 8 | Author
| H. Erm, Ann Krähling | Requires cookie* | | | Title
| Discrimination of Two Fusogenic Properties of Aqueous Polyethylene Glycol Solutions | | | | Abstract
| Investigations on the dose response of cell fusion, induced by ionfree aqueous polyethylene glycol (PEG) solutions, reveal distinct lowest fusogenic PEG concentrations for different permanently growing mammalian cell lines. Part o f the requisite PEG can be replaced by carbo hydrates, preserving the fusogenity o f the solutions. This discriminates two effects o f PEG solutions causing cell fusion: a) cell shrinkage, the required hyperosmolality o f the solutions may be provided by PEG or by carbohydrates, is supposed to cause intracellular processes necessary for consolidating polycaryons; b) membrane alterations, which can not be induced by carbo hydrates, enable intimate cell-cell contact via particle-free membrane areas. Depending on cell line salts can not only raise the osmolality o f PEG solutions but are able to co-operate with PEG in generating membrane alterations. | | | |
Reference
| Z. Naturforsch. 36c, 593—596 (1981); received March 111981 | | | |
Published
| 1981 | | | |
Keywords
| Cell Fusion, Polyethylene Glycol, Fusogenic Properties, Carbohydrates, Salts | | | |
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| default:Reihe_C/36/ZNC-1981-36c-0593.pdf | | | | Identifier
| ZNC-1981-36c-0593 | | | | Volume
| 36 | |
| 9 | Author
| M. Auro, Sola-Pennaa, JoseR. Oberto, M. Eyer-Fernandesb | Requires cookie* | | | Title
| Trehalose Protects Yeast Pyrophosphatase against Structural and Functional Damage Induced by Guanidinium Chloride | | | | Abstract
| Trehalose is accumulated at very high concentrations in yeasts when this organism is sub mitted to a stress condition. This report approaches the question on the protective effect of trehalose and its degradation product, glucose, against structural and functional damage promoted by guanidinium on yeast cytosolic pyrophosphatase. Here it is shown that both, 1 m trehalose or 2 m glucose, are able to attenuate at almost the same extent the conforma tional changes promoted by guanidinium chloride on the pyrophosphatase structure. On the other hand, while 1 m trehalose increases 3.8 times the K x (from 0.15 to 0.57 m) for guanidi nium chloride inhibition of pyrophosphatase activity, 2 m glucose did not even duplicate this parameter (from 0.15 to 0.25 m). These data support evidences for a functional reason for the accumulation by yeasts of trehalose, and not other compound, during stress conditions. | | | |
Reference
| Z. Naturforsch. 51c, 160—164 (1996); received September 15/November 15 1995 | | | |
Published
| 1996 | | | |
Keywords
| Trehalose, Yeast, Carbohydrate, Protection, Guanidinium Chloride | | | |
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| default:Reihe_C/51/ZNC-1996-51c-0160.pdf | | | | Identifier
| ZNC-1996-51c-0160 | | | | Volume
| 51 | |
| 10 | Author
| Jorge Saad-Nehme3b, JersonL. Silva3, JoseRoberto Meyer-Fernandes3 | Requires cookie* | | | Title
| Carbohydrates Protect Mitochondrial F0F j-ATPase Complex against Thermal Inactivation | | | | Abstract
| Federal do Rio de Janeiro, llha do Fundäo, 2 1 9 4 1 -5 9 0 . Rio de Janeiro, RJ, Brazil. Fax: (+ 55) (+21) 2 7 0 -8 6 4 7 . E-mail: meyer@bioqmed.ufrj.br Organisms and cellular systems are required to adapt to stress conditions like high tem per ature, often responding by accumulating organic solutes, such as sugars. This accumulation is associated with the effectiveness of these osmolytes in minimizing protein denaturation and membrane damage under stress conditions. In this work, we have studied the effect of sugars on the protection against thermal inactivation of mitochondrial FoFj-ATPase complex, in preparations of submitochondrial particles containing or depleted of inhibitor protein. We observed that after 15 min of pre-incubation at 70 °C of latent MgATP-submitochondrial particles (with inhibitor protein) in the presence of 1.5 m of sucrose or trehalose, or 3.0 m of glucose or fructose, about 80% of enzyme activity remained active. In the same conditions, but in the absence of sugars, the activity of the particles was completely abolished. Submi-tochondrial particles depleted of the inhibitor protein (A S-particles) were almost completely inactivated after 3 min of pre-incubation at 70 °C in the absence of sugars and more than 60% of the enzyme activity remained active when these particles were pre-incubated in the presence of sugars. In such condition, the enzyme acquires a more com pact and heat-stable conformation. Sugars, as well as the inhibitor protein, inhibit reversibly F 0F r ATPase com plex activity and protect this enzyme against inactivation by high temperature. Interestingly, the protection, promoted by sugars, of particles containing inhibitor protein is higher than of particles depleted of inhibitor protein, suggesting a synergism between sugar and inhibi tor protein. | | | |
Reference
| Z. Naturforsch. 55c, 594—5 (2000); received February 10/March 31 2000 | | | |
Published
| 2000 | | | |
Keywords
| Carbohydrates, Thermal Stabilization, Mitochondrial F 0F r ATPase | | | |
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| default:Reihe_C/55/ZNC-2000-55c-0594.pdf | | | | Identifier
| ZNC-2000-55c-0594 | | | | Volume
| 55 | |
| 11 | Author
| V. Villa, F. Fischer3, J. Thiemb | Requires cookie* | | | Title
| M | | | | Abstract
| o le k u la r e s V e rd rillu n g s v e rm ö g e n von K o h le n h y d ra t-D e riv a te n Helical Twisting Power of Carbohydrate Derivatives For the first time carbohydrate derivatives were systematically studied as doping material for a liquid crystalline phase. These compounds can exhibit a large twisting power. It may be controlled by the configurations of single chiral centers. Thus, a series of phenomena are realized in the cholesteric phase such as helix inversion, large or small temperature dependencies of the pitch, as well as broad blue phases. Durch Zugabe einer chiralen, löslichen Substanz zu einer nematischen Phase läßt sich die cholesterische Phase erzeugen [1], Neben neu synthetisierten Ver bindungen wurden auch zahlreiche Naturstoffe, vor nehmlich Isoprenoide eingesetzt. Kohlenhydratderi-vate wurden dagegen vermutlich aufgrund ihrer er heblichen Polarität bisher nicht in Betracht gezogen. Diese chemisch robusten und leicht zugänglichen Ver bindungen erscheinen ideal geeignet zu sein, da sich mit ihnen in einmaliger Weise alle stereochemischen Möglichkeiten realisieren lassen. Zur Überprüfung der Eignung von Kohlenhydrat-Derivaten als chirale Zusätze zu nematischen Phasen wurden 22 Mischungen untersucht. Als Wirtssubstanz diente jeweils 4-n-Butyloxy-phenyl-4'-n-hexyloxybenzoat (1, ZLI 1792). Als chirale Zusätze wurden gewählt (s. Tab. 1): | | | |
Reference
| Z. Naturforsch. 43a, 1119—1125 (1988); eingegangen am 30. September 1988 | | | |
Published
| 1988 | | | |
Keywords
| Helical twisting power, carbohydrates, induced cholesteric phase, diastereomers, liquid crystals | | | |
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| default:Reihe_A/43/ZNA-1988-43a-1119.pdf | | | | Identifier
| ZNA-1988-43a-1119 | | | | Volume
| 43 | |
| 13 | Author
| WilhelmV. Dahlhoffd, Karin Radkowskia, Ingo Dierkingb, Peter Zugenmaierb | Requires cookie* | | | Title
| Amphiphilic Carbohydrate-Based Mesogens, 12 [1] High-Yield Synthesis of Mesogenic l-O-Alkanoyl-D/L-Xylitols | | | | Abstract
| The equilibrium mixture of 1,2:3,4-and l,3:2,4-di-0-ethylboranediyl-D /L-xylitols 1 and 1' obtained on reaction o f three equivalents of xylitol with two equivalents of triethylboroxin, reacts with alkanoyl chlorides (heptanoyl-dodecanoyl) to give equilibrium mixtures of the O-ethylboranediyl protected l-O-alkanoyl-D.L-xylitols 2,2' after vacuum distillation. Depro tection of the latter affords the title amphiphilic esters 3 which melt to give the smectic A liquid-crystalline phase. | | | |
Reference
| Z. Naturforsch. 51b, 1229—1234 (1996); received April 26 1996 | | | |
Published
| 1996 | | | |
Keywords
| Carbohydrates, Amphiphiles, Liquid Crystals (Smectic), 1-0-A lkanoyl-D, L-X ylitols, X-Ray | | | |
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| default:Reihe_B/51/ZNB-1996-51b-1229.pdf | | | | Identifier
| ZNB-1996-51b-1229 | | | | Volume
| 51 | |
| 14 | Author
| Gianfranco Menestrina, Flavia Pasquali | Requires cookie* | | | Title
| Effects of Carbohydrates on the Ion Conductance of the Hemocyanin Channel | | | | Abstract
| The effects o f glucose and sucrose on the ionic conductance properties o f the channel formed by Megathura crenulata hemocyanin in planar lipid bilayers have been studied using m em branes o f different compositions. It was found that glucose at high concentrations strongly affects the time constants o f the current relaxations observed in m em branes containing many channels after a step in the voltage clamp from ground to a positive value. At m uch lower concentrations both sucrose and glucose strengthened the binding o f Ba2+ to the protein, what in turn has the effect to shift the conductance voltage curve o f the pore towards negative potentials. The possible mechanism underlying these effects and the analogies with other studies on the interaction o f sugars and alcohols with proteins have been discussed. | | | |
Reference
| Z. Naturforsch. 40c, 85—9 (1985); received October 25 1984 | | | |
Published
| 1985 | | | |
Keywords
| Hemocyanin Channel, Planar Lipid Bilayer, Carbohydrates, D ivalen t Cations, Protein Conformations | | | |
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| default:Reihe_C/40/ZNC-1985-40c-0085.pdf | | | | Identifier
| ZNC-1985-40c-0085 | | | | Volume
| 40 | |
|
