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1Author    W. Olfram Koller, Jürgen Frevert, H. Elm, Ut KindiRequires cookie*
 Title    Incomplete Glyoxysomes Appearing at a Late Stage of Maturation of Cucumber Seeds  
 Abstract    Seeds of cucumber fruits at a late stage o f ripening were analyzed for microbodies and micro­ body components. On isopycnic density gradient centrifugation of homogenates in the presence o f EDTA, several particulate fractions were obtained: a light membraneous fraction (density d = 1.09-1.11 kg x I-1), a mitochondria-enriched fraction (d = 1.21 kg x I-1), a microbody-enrich­ ed fraction (d = 1.23 kg x I-1), and a protein body fraction (d = 1.26-1.29 kg x I-1). Microbo­ dies were revealed by exactly coinciding peaks o f malate synthase, catalase and crotonase; small proportions of citrate synthase and malate dehydrogenase were also present in this zone. Isocitrate lyase activity, however, did not occur in the seeds at this stage. The examination of enzyme activi­ ties indicated the presence o f microbodies which cannot function as competent glyoxysomes be­ cause of the lack o f isocitrate lyase. Moreover, de novo synthesis from [3H] leucine could be de­ monstrated for malate synthase by means of immunoprecipitation of newly synthesized malate synthase and subsequent electrophoretic analysis. 
  Reference    Z. Naturforsch. 34c, 1232 (1979); received July 23 1979 
  Published    1979 
  Keywords    Microbodies, Malate Synthase, Cucumis sativus, Seed Ripening 
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 TEI-XML for    default:Reihe_C/34/ZNC-1979-34c-1232.pdf 
 Identifier    ZNC-1979-34c-1232 
 Volume    34 
2Author    W. Olfram Koller, Helm Ut KindlRequires cookie*
 Title    Rates of de novo Synthesis of Malate Synthase and Albumins during the Very Early Phase of Germination  
 Abstract    Malate synthase is synthesized de novo in the very early phase of germination. Its molecular and immunological properties do not differ from those o f malate synthase from fully developed cotyl­ edons. Radioactive leucine was administered to dry seeds of cucumber, and its incorporation into proteins o f cotyledons was examined after 2 days o f germination. The specific radioactivity of ma­ late synthase, purified by immunoprecipitation and electrophoresis on polyacrylamide gel, was only 1/20 the average value of the total albumin fraction. The minimal incorporation documented by the comparatively low specific activity o f isolated malate synthase is discussed in relation to the large pool of malate synthase already present in dry seeds. 
  Reference    Z. Naturforsch. 34c, 1237 (1979); received July 23 1979 
  Published    1979 
  Keywords    Protein Synthesis, Albumins, Malate Synthase, Cucumis sativus 
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 TEI-XML for    default:Reihe_C/34/ZNC-1979-34c-1237.pdf 
 Identifier    ZNC-1979-34c-1237 
 Volume    34 
3Author    P. Zipper, R. Wilfing, M. Kriechbaum, H. DurchschlagRequires cookie*
 Title    A Small-Angle X-Ray Scattering Study on Pre-Irradiated Malate Synthase. The Influence of Formate, Superoxide Dismutase, and Catalase on the X-Ray Induced Aggregation of the Enzyme  
 Abstract    The sulfhydryl enzyme malate synthase from baker's yeast was X-irradiated with 6 kGy in air-saturated aqueous solution (enzyme concentration; — 10 mg/ml; volume: 120 |al), in the absence or presence of the specific scavengers formate, superoxide dismutase, and catalase. After X-irradiation, a small aliquot of the irradiated solutions was tested for enzymic activity while the main portion was investigated by means of small-angle X-ray scattering. Additionally, an unir­ radiated sample without additives was investigated as a reference. Experiments yielded the fol­ lowing results: 1. X-irradiation in the absence of the mentioned scavengers caused considerable aggregation, fragmentation, and inactivation of the enzyme. The dose D \7 for total (= repairable + non­ repayable) inactivation resulted as 4.4 kGy. The mean radius of gyration was found to be about 13 nm. The mean degree of aggregation was obtained as 5.7, without correction for fragmenta­ tion. An estimation based on the thickness factor revealed that about 19% of material might be strongly fragmented. When this amount of fragments was accordingly taken into account, a value of 7.1 was obtained as an upper limit for the mean degree of aggregation. The observed retention of the thickness factor and the finding of two different cross-section factors are in full accord with the two-dimensional aggregation model established previously (Zipper and Durchschlag, Radiat. Environ. Biophys. 18, 99 — 121 (1980)). 2. The presence of catalytic amounts of superoxide dismutase and/or catalase, in the absence of formate, during X-irradiation reduced both aggregation and inactivation significantly. 3. The presence of formate (10 or 100 m M) during X-irradiation led to a strong decrease of aggregation and inactivation. This effect was more pronounced with the higher formate concen­ tration or when superoxide dismutase and/or catalase were simultaneously present during X-irradiation. The presence of formate also reduced the amount of fragments significantly. 4. The results clearly show that the aggregation and inactivation of malate synthase upon X-irradiation in aqueous solution are mainly caused by OH"; to a minor extent OJ and H20 2 are additionally involved in the damaging processes. 
  Reference    Z. Naturforsch. 40c, 364 (1985); received December 10 1984/February 12 1985 
  Published    1985 
  Keywords    Malate Synthase, Radioprotection, Small-Angle Scattering, Specific Additives, X-Ray Induced Aggregation 
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 TEI-XML for    default:Reihe_C/40/ZNC-1985-40c-0364.pdf 
 Identifier    ZNC-1985-40c-0364 
 Volume    40 
4Author    Helmut Durchschlag1, Peter Zipper2Requires cookie*
 Title    X-Ray Induced Inactivation of the Sulfhydryl Enzyme Malate Synthase in the Presence of Various Additives Probing the Extent of Primary and Post-Irradiation Inactivation and Repair by Rapid Screening on the Microlevel  
 Abstract    The sulfhydryl enzyme malate synthase was inactivated by X-irradiation in air-saturated aqueous solution, in the absence or presence of a variety of additives (thiols, antioxienzymes, typical radical scavengers, inorganic salts, buffer components, substrates, products, ana­ logues). Radiation-induced changes of enzymic activity were registered immediately after stop of irradiation and in the post-irradiation period. Repair experiments were initiated by post­ irradiation addition of dithiothreitol. Additionally, post-irradiation inactivation was modulat­ ed by some further additives. Probing the extent of primary and post-irradiation inactivation and repair was accomplished effectively by screening experiments on the microlevel, and by derivation of normalized efficiency parameters which allowed quick comparisons of the var­ ious additives with respect to their protective and repair-promotive efficiencies. Correlations between the efficiency parameters were studied by means of binary and ternary diagrams. Most of the substances added before irradiation were found to protect the enzyme against pri­ mary and post-irradiation inactivation and to increase the reparability of the enzyme by dithiothreitol, the extent of the effects depending on the nature (and concentration) of the ad­ ditives used. Our results indicate that both specific protection (by substrates, products, ana­ logues, and by sulfhydryl agents) and scavenging are responsible for the radioprotective effi­ ciencies of the additives. 
  Reference    Z. Naturforsch. 45c, 645—654 (1990); received November 15 1989 
  Published    1990 
  Keywords    Malate Synthase, X-Ray Inactivation, Post-Irradiation Effects, Repair, Screening of Radioprotectives 
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 TEI-XML for    default:Reihe_C/45/ZNC-1990-45c-0645.pdf 
 Identifier    ZNC-1990-45c-0645 
 Volume    45 
5Author    Peter ZipperRequires cookie*
 Title    Small-Angle X-Ray Scattering Studies on the X-Ray Induced Aggregation of Malate Synthase Computer Simulations and Models  
 Abstract    Malate synthase undergoes an X-ray induced aggregation which can be monitored in situ by small-angle X-ray scattering; the analysis o f scattering curves, taken at subsequent stages o f aggregation, has led to the establishment of a tentative model for an aggregation in two dimensions (Zipper and Durchschlag (1980) Rad. and Environm. Biophys., in press). This model was checked by comparison o f appropriate theoretical curves with the experi­ mental curves. The theoretical scattering curves for this comparison were obtained by weighted averaging over the scattering curves calculated for various species o f hypothetical aggregates. Based on the approximation o f the unaggregated enzyme particle by an oblate cylinder, the aggregates were assumed to be composed of 2, 3, 4 or 6 of such cylinders, associated side-by-side in one and later on in two linear rows. The weight fractions o f the species were chosen so, that an optimum fit of the experimental mean radii o f gyration and mean degrees o f aggregation was achieved. The distance distribution functions calculated for the model are very similar to the functions derived from the scattering experiment. Cross-section Guinier plots o f the scattering curves of the model reveal the occurrence o f one and later on o f two pseudo cross-section factors similar to those observed in the experimental scattering curves. The pseudo thickness factor of the model of the unaggregated particle is found to be retained in the model curves for all stages of aggregation. From these results it can be concluded that the model for the aggregation process is essentially consistent with the scattering behaviour of the aggregating enzyme. Small differences between the theoretical and experimental curves may be explained by the idealizations o f the model. The comparison of theoretical curves for alternative models, assuming aggregation in three dimen­ sions, suggests that these models are unlikely, though small amounts o f three-dimensional aggregates cannot be ruled out completely. 
  Reference    Z. Naturforsch. 35c, 890—901 (1980); received November 12 1979/July 14 1980 
  Published    1980 
  Keywords    Malate Synthase, Small-Angle X-Ray Scattering, X-Ray Induced Aggregation, Computer Simula­ tions, Models for the Aggregation Process 
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 TEI-XML for    default:Reihe_C/35/ZNC-1980-35c-0890.pdf 
 Identifier    ZNC-1980-35c-0890 
 Volume    35 
6Author    H. Elm, Ut Durchschlag, Peter ZipperRequires cookie*
 Title    Electrophoretic and Chemical Studies on the X-Ray Damage of Malate Synthase  
 Abstract    The sulfhydryl enzyme malate synthase was shown to undergo an X-ray induced aggregation and inactivation in solution (Zipper and Durchschlag, Radiat. Environ. Biophys. 18, 99-121 (1980)). Further evidence for the occurrence o f aggregation and inactivation and also of fragmen­ tation and partial unfolding of the enzyme upon X-irradiation was obtained by chemical and electrophoretic studies. Irradiation was carried out in a specially designed microcell, experiments were performed on the microlevel. Under conditions o f the experiments the formation of H20 2 upon X-irradiation could be proven; therefore the influence of H20 2 on the enzyme was investigated too. Though the quantitative results o f the damaged enzyme particles are influenced by many disturbing factors, the findings allow clear statements on the nature of the effects under investigation. 1) Both X-irradiation and treatment with H20 2 caused a decrease of total and an increase o f available sulfhydryl groups o f the enzyme and led to a loss o f enzymic activity. The presence o f dithiothreitol turned out to be able to protect the enzyme against X-ray or H20 2 induced inactivation. Moreover, addition of dithiothreitol after X-irradiation or H20 2 treatment allowed a considerable repair o f enzymic activity. 2) Polyacrylamide gel disc electrophoreses o f X-irradiated enzyme solutions, performed in the presence of sodium dodecyl sulfate, showed the occurrence o f covalently cross-linked subunits (preferably dimers and trimers) and of various definite fragments. Electrophoreses in the absence of the denaturant indicated the occurrence o f enzyme aggregation. The effects were more pronounced with increasing X-ray doses. The electrophoreses also clearly reflected a radioprotec­ tion by dithiothreitol against cross-linking, but not against fragmentation. Addition o f excess of 2-mercaptoethanol or of dithiothreitol to the X-irradiated enzyme clearly demonstrated that part of the covalent cross-links were disulfide bridges; the aggregates themselves, however, were held together primarily by non-covalent bonds. Blocking of exposed enzyme sulfhydryls by means of Ellman's reagent prevented both covalent cross-linking and enzyme aggregation. 3) Similar electrophoretic patterns as found for the X-irradiated enzyme were obtained for the unirradiated enzyme after treatment with H 20 ?. The similarity o f the electropherograms, as well as the reversible diminution o f enzymic activity and the loss o f sulfhydryls in the presence of H20 2, suggest an involvement o f H20 2 in the radiation damage o f the enzyme. It seems plausible that oxidation reactions are responsible for the effects caused by X-irradiation or H20 2 treatment. 
  Reference    Z. Naturforsch. 36c, 516—533 (1981); received November 12 1979/February 4 1981 
  Published    1981 
  Keywords    Malate Synthase, Radiation Damage, PAGE, Protection and Repair by Dithiothreitol, Effects of Hydrogen Peroxide 
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 TEI-XML for    default:Reihe_C/36/ZNC-1981-36c-0516.pdf 
 Identifier    ZNC-1981-36c-0516 
 Volume    36 
7Author    Martin Semara, HeidrunA. Nke3, Wolf-Rüdiger Arendholzb, Robert Veiten0, Wolfgang Steglich0Requires cookie*
 Title    Lachnellins A, B, C, D, and Naphthalene-l,3,8-triol, Biologically Active Compounds from a Lachnellula Species (Ascomycetes)  
 Abstract    In the course of our search for new biologically active metabolites, lachnellin A (1), a metabolite with high cytotoxic and antimicrobial activities, the structurally related lachnellins B. C and D (3, 4, 7), and naphthalene-l,3,8-triol (8), an inhibitor of malate synthase (EC, were isolated from submerged cultures o f the ascomycete Lachnellula sp. A 3 2 -8 9 . The antimicrobial, cytotoxic and phytotoxic activities of lachnellin A depended on its reactiv­ ity and could be abolished by the addition of cysteine. The enzyme inhibiting activity of (8) was due to reactive intermediates during melanization and was no longer observed in the presence of serum albumin. In addition, rac-scytalone (9), (+)-fra/7s-3,4-dihydro-3,4,8-trihy-droxy-l(2//)-naphtha!enone (10). 2,5-dihydroxytoluene (11), and (/?)-(-)-5-methylmellein (12) were obtained from the same source and biologically characterized. 
  Reference    Z. Naturforsch. 51c, 500 (1996); received March 1/April 29 1996 
  Published    1996 
  Keywords    Lachnellin A, B, C D Glyoxylate Cycle, N aphthalene-1, 3, 8-triol, Malate Synthase, Melanization, Lachnellula sp 
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 TEI-XML for    default:Reihe_C/51/ZNC-1996-51c-0500.pdf 
 Identifier    ZNC-1996-51c-0500 
 Volume    51