bluuebunny/crossref_metadata_2025_split huggingface dataset:
UDP-Glucose: Flavonol 7-O-glucosyltransferase Activity in Flower Extracts of Chrysanthemum segetum
Authors: Stich K. , Halbwirth H. , Wurst F. , Forkmann G. 
Published: August 2018

Abstract
The yellow colour of Chrysanthemum segetum petals is due to the presence of the 7-O-glucosides of quercetin and particularly gossypetin (8-hydroxyquercetin). In petal extracts of C. segetum an enzyme was demonstrated which catalyzes the transfer of the glucosyl moiety of uridine 5'-diphosphoglucose (UDPG) to the 7-hydroxyl group of flavonols with gossypetin and quercetin as the best substrates. Besides flavonols flavanones and flavones were found to be glucosylated in the 7-position. The pH-optimum of the reaction highly depended on the substrate used. With quercetin as substrate, maximal enzyme activity occurred at a pH of 8.25 and a temperature of 25 °C, but 7-O-glucosylation also proceeded at low temperatures. Studies on temperature stability revealed, that there was no influence on the glucosylation reaction up to 40 °C. Higher temperatures led to a loss of enzyme activity. Using gossypetin as a substrate a similar course of temperature stability was observed. Addition of Mg2+, Ca2+ and KCN slightly stimulated 7-O-glucosylation, whereas Co2+, Cu2+, Fe2+, Hg2+, p-hydroxymercuribenzoate and N-ethylmaleimide showed a strong inhibitory effect. Additional enzymatic studies were performed with the commercial strain " Stern des Orients" where gossypetin 7-O-glucoside is restricted to the inner parts of the petals. For enzyme extracts from both parts of the petals gossypetin was found to be the most attractive substrate. In comparison to quercetin (133.4 μkat / kg protein) an about three times higher specific activity of the 7-O-glucosyltransferase(s) was determined with gossypetin (382.1 μkat/ kg protein) as substrate, indicating that hydroxylation of quercetin in 8-position to gossypetin precedes 7-O-glucosylation.
Enzymatic and Electrochemical Reactions of Xanthine Oxidase Immobilized on Carbon Materials
Authors: Horozova E. , Dimcheva N. , Jordanova Z. 
Published: August 2018

Abstract
An optimum way of immobilizing xanthine oxidase on graphite was found where a redox transformation of the enzyme was observed. The nature of the redox maxima was hypothe­ sized on the basis of the dependence of the half-wave potential (Ep/2) on the pH of the solution. The enzymatic activity of xanthine oxidase adsorbed on two kinds of soot was studied by the oxidation of xanthine. The kinetic and activation parameters of the enzyme reaction were determined.
Characterization and Cloning of Cutinase from Ascochyta rabiei
Authors: Tenhaken Raimund , Arnemann Martin , Köhler Gabriele , Barz Wolfgang 
Published: August 2018

Abstract
Ascochyta rabiei, the causal agent of Ascochyta blight on chickpea plants, secretes a cutinase in the culture filtrate when it is induced by cutin or hydroxylated fatty acids. This cutinase is the main esterase in the culture fluids. The enzyme was purified to homogeneity by three successive chromatographic steps. It showed an apparent molecular weight of 22 kD in SDS-PAGE and cleaved ester bonds of 3H-labelled cutin or p-nitrophenylbutyrate with maximal activities around pH 8. As a serine esterase, cutinase is strongly inhibited by organophosphorous compounds and the most effective inhibitor 2,3,5-trichloropyridine-6-(0-methyl-O-n-butyl)-phosphateester (MAT 9564) shows a K1 value of 0.8 nᴍ. The cutinase gene was cloned from a genomic cosmid library by screening with two oligonucleotides directed against cutinase consensus peptides. The gene was subcloned to a 1.7 Kb Sa1l/Hindlll-insert and sequenced. The cutinase gene codes for a 223 amino acid protein with strong homology to other fungal cutinase sequences. The purified cutinase is encoded by a single copy gene.
Role of Hydrophobic and Hydrophilic Interactions of Organotin and Organolead Compounds with Model Lipid Membranes
Authors: Gabrielska Janina , Sarapuk Janusz , Przestalski Stanisław 
Published: August 2018

Abstract
The present study was conducted to clarify the mechanism of toxicity of organic compounds using lipid model membranes (liposomes and planar lipid membranes).
The compounds studied were trialkyltin and trialkyllead chlorides, dialkyltin dichlorides and some inorganic forms of those metals. Two different (anionic and cationic) detergents were also used in the experiments to change the surface properties of liposomes. As a measure of interaction between the compounds studied and model membranes were the release of liposome bound praseodymium and the change in stability of planar membranes under the influence of those compounds.
On the basis of the results obtained it was postulated that the mechanism of interaction between tin-and leadorganics and model lipid membranes is a combination of different factors featuring interacting sides. The most important properties determining the behaviour of organic compounds in the interaction were lipophilicity and polarity of different parts of the organics and the steric arrangement they can take in the medium. On the other hand, the surface potential of the lipid bilayer and the environment of the lipid molecules, that play a significant role in the availability of the lipid bilayer to the organics, were important factors in the interaction.
Serological Characterization of Hungarian Plum Pox Virus Isolates
Authors: López-Moya Juan José , López-Abella Dionisio , Díaz-Rúiz José-Ramón , Martinez-Garcia Belén , Gáborjányi Richard 
Published: August 2018

Abstract
Three Hungarian (No.2, 4 and 9), and a Moldavian (K) plum pox virus isolates were compared with a characterized Spanish isolate (5.15) by RT-PCR, ELISA, dot-blot and West­ern blot analysis. Monoclonal antibodies prepared against the external, intermediate and internal sequences of the coat protein of the Spanish isolate were able to differentiate the four isolates. Hungarian isolate No. 2 proved to be serologically identical to the Spanish isolate, while No. 4 showed appreciable differences and No. 9 could be recognized only by the monoclonal antibodies representing the intermedial and internal parts of the coat protein. K isolate showed a more distant relationship to other isolates. Our experiment provided the first demonstration of the presence of D type isolates in Hungary.
Phenolics from Cell Suspension Cultures of Penstemon serrulatus; Relation to Plant Organs
Authors: Skrzypek Zuzanna , Wysokińska Halina 
Published: August 2018

Abstract
By repeated selection of pigment portions of tissue the red callus induced from root seed­lings of Penstemon serrulatus Menz. was chosen for suspension culture, which was maintained in Schenk and Hildebrandt medium supplemented with naphthaleneacetic acid (0.2 mg/l), 6-benzylaminopurine (2 mg/l) and sucrose (50 g/l). From the cultured cells eight phenolic compounds were isolated. They were identified as cyanidin 3-O-glucoside, delphinidin 3-O-glucoside, luteolin, luteolin 7-O-glucoside, norartocarpetin 7-O-glucoside, verbascoside, martynoside and leucosceptoside A. The kind of cell line, its age and light irradiation were important factors in flavonoid production, but production of phenylpropanoid glycosides was found to be unaffected by these factors. The phenolic composition found in the cell culture was compared with those in the flowers and leaves of original plants of P. serrulatus.
Nonphotochemical Quenching of Chlorophyll Fluorescence in Higher Plant Leaves Studied by Delayed Fluorescence Decay Measurements
Authors: Terjung Frank , Maier Karlheinz 
Published: August 2018

Abstract
Delayed chlorophyll fluorescence decay measurements on the second time scale were applied to investigate the state of photosystem II under different photosynthetic conditions. Leaves adapted to high and low light intensities were used to study the effects of nonphotochemical quenching (energy quenching) on the photosynthetic state. 3-(3,4-dichlorophenyl)- 1,1-dimethylurea (DCM U)-treated leaves were used to characterize the photosynthetic state in the absence of a transthylakoid ApH, dithiothreitol (DTT)-treated leaves in the absence of the xanthophyll zeaxanthin. The fast decay components were the most affected by energy quenching as indicated by increased decay times. The slowest decay component was hardly affected, neither in amplitude nor in decay time. The measurements indicate a relaxation of energy quenching on the second time scale and the absence of damages in the electron transfer chain of PS II. The constant decay times of the DTT-treated leaf, comparable to those of the DCMU-treated leaf, indicate the obligatory role of zeaxanthin for most of the detected energy quenching.
Does Astaxanthin Protect Haematococcus against Light Damage?
Authors: Fan Lu , Vonshak Avigad , Zarka Aliza , Boussiba Sammy 
Published: August 2018

Abstract
The photoprotective function of the ketocarotenoid astaxanthin in Haematococcus was questioned. When exposed to high irradiance and/or nutritional stress, green Haematococcus cells turned red due to accumulation of an immense quantity of the red pigment astaxanthin. Our results demonstrate that: 1) The addition of diphenylamine, an inhibitor of astaxanthin biosynthesis, causes cell death under high light intensity; 2) Red cells are susceptible to high light stress to the same extent or even higher then green ones upon exposure to a very high light intensity (4000 μmol photon m-2 s-1); 3) Addition of 1O2 generators (methylene blue, rose bengal) under noninductive conditions (low light of 100 (μmol photon m-2 s-1) induced astaxanthin accumulation. This can be reversed by an exogenous 1O2 quencher (histidine); 4) Histidine can prevent the accumulation of astaxanthin induced by phosphate starvation. We suggest that: 1) Astaxanthin is the result of the photoprotection process rather than the protective agent; 2) 1O2 is involved indirectly in astaxanthin accumulation process.
Phosphorylase Phosphatase Activity in Saccharomyces cerevisiae 257
Authors: Christova Nelly , Galabova Danka 
Published: August 2018

Abstract
Phosphorylase Phosphatase, Protein Phosphatase, Saccharomyces cerevisiae Aphosphatase, active towards phosphorylase a and phosphorylated proteins casein and histone II-A , was isolated from Saccharomyces cerevisiae 257. The enzyme dephosphorylated glycogen phosphorylase from commercial yeast rendering it inactive. The protein phosphatase activity was not influenced by any metal ions. Phosphorylase phosphatase activity was slightly stimulated by p -nitrophenyl phosphate and inhibited by heparin.
Determination of C/N Ratios Required for De-Repression of Nitrogenase in Rhodobacter capsulatus
Authors: Dörffler Michael , Steindorf Astrid , Oelze Jürgen 
Published: August 2018

Abstract
Phototrophic continuous and batch cultures of Rhodobacter capsulatus were employed to identify the C/N ratio above which nitrogenase is de-repressed. The cultures were grown with limiting amounts of ammonium as source of bound nitrogen and with ʟ-lactate or ʟ-malate as sources of carbon and reducing equivalents. De-repression of nitrogenase was determined on the basis of the occurrence of dinitrogen fixation, acetylene reduction and nifH promoter activities as well as on the basis of hydrogen evolution and nitrogenase poly­ peptides. In continuous culture, cells started to fix dinitrogen, to reduce acetylene, to activate the nifH promoter and to form nitrogenase polypeptides, when consuming lactate per ammonium at a C/N ratio of about 6 (this ratio represents the number of C and N atoms consumed). With malate as carbon source all of the activities becam e detectable above a C/N ratio of about 8. Essentially the same C/N ratios were determined with batch cultures for the occurrence of N -limitation of growth and hydrogen evolution. The experimentally deter­mined C/N ratios for nitrogenase de-repression essentially agreed with C/N ratio of 5.8 and 7.8 calculated for the assimilation of ammonium and either lactate or malate, into biomass of an elemental com position of CH1.83N0.183O0.5-This means that the occurrence of N -limitation and nitrogenase de-repression is defined by a threshold C/N ratio required for biomass production. As experimentally and theoretically shown, this ratio depends on the reduction state of the carbon source. It is concluded that the C/N ratio of nutrient consumption represents an intracellular signal which is directly translated into nitrogenase de-repression.
Interference by Nickel(II) Salts and Their 5-Methylimidazole-4-carboxylate Coordination Compounds on the Chloroplast Redox Chain
Authors: King-Díaz Beatriz , Barba-Behrens Nórah , Montes-Ayala Josefina , Castillo-Blum Silvia E. , Escartín-Guzmán Concepción , Iglesias-Prieto Roberto , Lotina-Hennsen Blas 
Published: August 2018

Abstract
Nickel(II) salts and their coordination com pounds with ethyl 5-m ethylim idazole-4-carboxylate (emizco), [Ni(emizco)2Cl2], [Ni(emizco)2Br2], [Ni(emizco)2(H2O)2] (NO3)2 H2O · Ni(NO3)2, inhibit photosynthetic electron flow (basal, phosphorylating and uncoupled) and ATP-synthesis, therefore behave as Hill reaction inhibitors. Coordination compounds are more potent inhibitors than the salts. It was found that the target for NiCl2; NiBr2 and Ni(NO3)2 is at the b6f level. On the other hand, the complexes [Ni(Emizco)2Cl2], [Ni(Emizco)2Br2] and [Ni(emizco)2(H2O )2] (NO3)2H2O binding sites are located at QB(D1)-protein and b6f level. Therefore, they have a common inhibition site located at b6f avoiding the PQH2 oxidation. The QB inhibition site was corroborated by variable chlorophyll a fluorescence yield [V(j)]. The emizco ligand has no activity on photosynthetic electron flow.
Correlation between Virulence of Various Strains of Mycobacteria and Their Susceptibility to Ethanolic Extract of Propolis (EEP)
Authors: Scheller Stan , Kawalski Henryk , Oklek Kazimierz , Dworniczak Szymon , Matsuno Tetsuya , Waldemar-Klimmek Krystian , Rajca Marek , Shani ashovam 
Published: August 2018

Abstract
extract of propolis (EEP) has antibacterial, antiviral, antiprotozoal and antifungal properties, in addition to many biological effects. Our laboratory has demonstrated a syner­gistic effect of EEP and antibiotics on the growth of Staphylococcus aureus, and suggested that the bactericidal effect of EEP was expressed mainly on virulent mycobacteria rather than on non-virulent (attenuated) ones. The present study was designed to reconfirm the latter finding, by subjecting 17 different mycobacteria strains to EEP, and evaluating whether there is a correlation between the virulence of the mycobacteria strains studied and their susceptibility to EEP. Our findings demonstrate that while the four non-virulent strains studied are not susceptible to EEP, out of the 13 virulent strains studied seven are susceptible and six are resistant to it. These results suggest that while there is no full correlation between virulence of the mycobacteria tested and their susceptibility to EEP, the few strains that were resistant to EE P were non-virulent.
Superoxide-Dependent and -Independent Nitrite Formation from Hydroxylamine: Inhibition by Plant Extracts
Authors: Rohnert Ute , Schneider Werner , Elstner Erich F. 
Published: August 2018

Abstract
Reactive oxygen species such as OH·, peroxynitrite and the non-radical, hypochlorous acid, play outstanding roles in many diseases. The formation of OH·(Fenton-)-type radicals is catalyzed by enzymes such as xanthine oxidase (XOD) via one-electron reduction of mo­lecular oxygen producing superoxide radical anions (O2·-). Subsequent transfer of one elec­ tron to hydrogen peroxide by Fe2+ or Cu+-ions yields OH-radicals measurable as ethene release from 1-keto-4 methylthiobutyrate (KMB). Xanthine oxidase or activated neutrophils are prominent sources of this strong oxidant produced at inflammatory sites. Many natural compounds such as salicylates or flavonoids interfere either with the pro­ duction of these activated oxygen species or function as radical scavengers and thus as antiox­ idants. Extracts from willow-bark (Salix spec.) and also other species such as ash-tree (Fraxi-nus spec.) or poplar (Populus spec.) have been used as antiinflammatory drugs since a long time. In this communication we wish to report on model reactions to demonstrate a) the radical scavenging activities of such plant extracts inhibiting ethene release from KMB induced by Fenton-type oxidants and b) the inhibition of the formation of nitrogen monoxide (NO) from hydroxylamine includ­ing XOD either in the presence or absence of myoglobin (MYO) measurable as nitrite forma­tion: In the absence of MYO, superoxide dismutase is an excellent inhibitor of nitrite forma­tion but is inactive in its presence. Extracts from the willow-bark or the drug PhytodolorR, however, are inhibitory both in the presence and absence of MYO. As active principle, the flavonoid rutin included in these extracts is likely to function as one inhibitor of the XOD-mediated reaction.
The Exogenous NADH Dehydrogenase of Heart Mitochondria Is the Key Enzyme Responsible for Selective Cardiotoxicity of Anthracyclines
Authors: Nohl H. , Gille L. , Staniek K. 
Published: August 2018

Abstract
The molecular mechanism of the anthracycline-dependent development of cardiotoxicity is still far from being clear. However, it is generally accepted, that mitochondria play a significant role in triggering this organ specific injury. The results presented in this study demonstrate that, in contrast to liver mitochondria, isolated heart mitochondria shuttle single electrons to adriamycin, giving rise to oxygen radical formation via autoxidation of adria­mycin semiquinones. This one electron reduction of anthracyclines is catalyzed by the exoge­nous NADH dehydrogenase associated with complex I of heart mitochondria, an enzyme which is lacking in liver mitochondria. Upon addition of NADH heart mitochondria generate significant amounts of adriamycin sem iquinones while liver mitochondria were ineffective. Adriamycin semiquinones undergo both autoxidation leading to superoxide radical release and complex reactions under formation of adriamycin aglycone. Due to the high lipophilicity adriamycin aglycones accumulate in the inner mitochondrial membrane where they interfere with electron carriers of the respiratory chain. Adriamycin aglycone sem iquinones emerging from an interaction with complex I were found to trigger homolytic cleavage of H2O2 which results in the formation of hydroxyl radicals. As demonstrated in this study the activation of adriamycin by the exogenous NADH dehydrogenase of cardiac mitochondria initiates a cas­cade of reaction steps leading to the establishment of oxidative stress. Our experiments sug­ gest the exogenous NADH dehydrogenase of heart mitochondria to play a key role in the cardiotoxicity of adriamycin. This organ-specific enzyme initiates a sequence of one electron transfer reactions ending up in the establishment of oxidative stress.
Production of Antibiotics by Collybia nivalis, Omphalotus olearius, a Favolaschia and a Pterula Species on Natural Substrates
Authors: Engler Michaela , Anke Timm , Sterner Olov 
Published: August 2018

Abstract
Collybia nivalis, Favolaschia sp. 87129, Pterula sp. 82168 and Omphalotus olearius were cultivated on natural substrates. The antibiotic metabolites oudemansin A, strobilurins A, D. illudin S and pterulone were isolated and identified. A new antifungal metabolite, pterulone B, was described from cultures of Pterula sp. 82168 on wood. Collybia nivalis was found to be the first species of this genus to produce strobilurins and oudemansin A. As compared to rich media the cultivation on natural substrates resulted in the production of fewer metabolites. The concentrations of the antibiotics, however, were sufficient to inhibit other saprophytic fungi.
Yeast Permeabilization as a Tool for Measurment of in situ Enzyme Activity: Localization of Alkaline Phosphatase
Authors: Spasova D. , Galabova D. 
Published: August 2018

Abstract
The biochemical and ultracytochemieal localization of alkaline phosphatases in permeabilized cells of Saccharomyces cerevisiae 257 has been studied. The treatment with non-ionic surfactant Triton X-100 allows the penetration of the substrate into intact yeast cells and thus provides detailed detection of the enzyme activity in ultracytochemical studies.
Nuclear Translocation of Tissue Type Transglutaminase during Sphingosine-Induced Cell Death: A Novel Aspect of the Enzyme with DNA Hydrolytic Activity
Authors: Takeuchi Yutaka , Ohashi Hiroshi , Birckbichler Paul J. , Ikejim Takashi 
Published: August 2018

Abstract
Tissue type (type 2) transglutaminase (TGase, EC 2.3.2.13) has been implicated in various cellular processes including cell death. In order to better understand the role of this enzyme in cell death, human melanocytic A375-S2 cells were treated with sphingosine, a cell-signaling mediator. During the rapid onset of cytotoxicity caused by this lipidic agent, tissue TGase was translocated from the cytoplasm to the cell nuclei. This observation was further remarked in relevance to its previously undescribed activity for DNA degradation. The DNA hydrolytic activity associated with tissue TGase was dependent on Mg2+ in contrast to the Ca2+ requirement for the classical cross-linking acrivity of TGase, and was inhibited by Zn2+. Based on the results shown here, we propose a novel aspect of tissue TGase in cell death.
A New Bromotyrosine Alkaloid from the Caribbean Sponge Aiolochroia crassa
Authors: Assmann Michael , Wray Victor , van Soest Rob W. M. , Proksch Peter 
Published: August 2018

Abstract
A detailed analysis of the chemical constituents of a Caribbean specimen of Aiolochroia crassa was performed. Five brominated products (1 -5) were isolated and one of these was a new bromotyrosine metabolite. The structure of the new compound 1 has been established from spectral studies. Compounds 1 and 2, which are the major brominated metabolites and have not been previously identified in any Aiolochroia species, could be usefully employed as chemotaxonomic markers.
Constituents of Brazilian Geopropolis
Authors: Bankova V. , Christov R. , Marcucci C. , Popov S. 
Published: August 2018

Abstract
Three samples of Brazilian geopropolis, collected by three indigenous bee species, were investigated by GC/MS. More than 50 compounds were identified, mainly terpenoids and phenolics. The chemical composition of propolis gathered by different bee species was different.