bluuebunny/crossref_metadata_2025_split huggingface dataset:
Semisynthetic Preparation of 1-O-hexadecyl-2-acetyl-sn-glyceryl-3- phosphorylcholine (Platelet Activating Factor)
Authors: Lekka Marilena E. , Tsoukatos Demokritos C. , Tselepis Alexandras D. , Kapoulas Vassilios M. 
Published: August 2018

Abstract
1-O-hexadecyl-2-acetyl-sn-glyceryl-3-phosphorylcholine (platelet activating factor, PAF), (1.9 μmol) was prepared from the total lipid extract of the protozoan Tetrahymena pyriformis 9 × 107 cells. The procedure involved mild alkaline hydrolysis of the total lipids, followed by acetylation and purification of the product by preparative TLC and HPLC . The yield was 60 % with respect to the content of 1-O-alkyl-2-acyl-sn-glyceryl-3-phosphorylcholine in the total lipids, determined after preparative TLC . The alkyl side chain of the semisynthetic PAF was composed of hexadecyl residue. Our product was identified as PAF according to its biological activity, the chromatographic behaviour on TLC and HPLC , the physicochemical properties and the behaviour under treatment with PLA2 and Lipase from Rhizopus arrhizus. The above procedure is proposed as a facile, inexpensive and convenient method.
Measuring P700 Absorbance Changes around 830 nm with a New Type of Pulse Modulation System
Authors: Schreiber Ulrich , Klughammer Christof , Neubauer Christian 
Published: August 2018

Abstract
A new measuring system for monitoring absorbance changes around 830 n m is described, which was developed by modification of a commercially available pulse modulation fluorometer. All modifications concern the emitter-detector unit of the fluorometer, such that only this unit needs to be exchanged when changing from fluorescence to absorbance measurements and vice versa. The new system is shown to be well-suited for measuring redox changes of P700, the reaction center of photosystem I, in intact leaves and isolated chloroplasts. The observed kinetic changes at 830 nm in response to single turnover or multiple turnover saturating flashes are practically identical to those previously measured around 700 nm . The signal/noise ratio is sufficiently high to give well-resolved kinetics without signal averaging. W h e n P700 is oxidized by far-red background light, valuable information on the state of the intersystem electron transport chain is given by the re-reduction kinetics induced by single or multiple turnover saturating flashes. Such measurements are facilitated by the use of poly-furcated fiberoptics. With intact leaves, almost identical responses are found when measuring through the leaf (transmission mode) or from the leaf surface (remission mode). Modulated chlorophyll fluorescence can be measured in parallel; application of saturation pulses for fluorescence quenching analysis produces transient P700 oxidation without oversaturating the measuring system. The information on the P700 redox state complements that obtained from fluorescence measurements, yielding a new practical tool in plant physiological research.
Immunological Study on the Structural Difference between Ribulose- 1,5-bisphosphate Carboxylase/Oxygenase from Nicotiana tabacum var. John William's Broadleaf and the Tobacco Mutant Su/su
Authors: Nespoulous C. , Fabisch P. , Radunz A. , Schmid G. H. 
Published: August 2018

Abstract
In the present paper we have attempted to characterize by means of immunological methods the molecular difference between ribulose 1,5-bisphosphate carboxylase/oxygenase from the wild type TV. tabacum var. John William's Broadleaf and the tobacco mutant Su/su. The tobacco mutant Su/su exhibits in comparison to the wild type a higher photorespiratory activity. The reagents used in the present study are monospecific antisera to the two bifunctional enzymes to be compared. We have analyzed the oxygenase activity of the two enzymes in dependance on the binding of the amount of antibodies out of the homologous and the not homologous antiserum. These analyses have shown, that the enzymes of both phenotypes were 4 0 % stronger inhibited in the equivalence regions with respect to their oxygenase function by antibodies of the antiserum to ribulose 1,5-bisphosphate carboxylase/oxygenase of the mutant than by antibodies of the wild type antiserum. It should be noted that the antiserum to the mutant enzyme exhibits a 25 % lower antibody titer, than the antiserum to the wild type enzyme.
In the region of extreme antibody excess, i.e. when antibodies are mostly monovalently bound and most antigenic determinants are saturated with antibodies, the oxygenase activity of both enzymes decreases towards zero in the presence of the homologous as well as in the presence of non-homologous antibodies. In the region of excess of antigenic determinants, that is when only a few antibody molecules can bind onto the enzymes, only the oxygenase activity of the mutant enzyme is inhibited by its homologous antibodies by 40 % . This apparent difference in the molecular structure of the two bifunctional enzymes to be compared is neither caught in the double immuno diffussion test nor in the tandem crossed immuno electrophoresis, using the two antisera as test reagents. In all cases only fused precipitation bands are observed.
Chemical modification of ribulose 1,5-bisphosphate carboxylase/oxygenase by hydroxylamine treatment or treatment with o-(p-nitrophenyl)hydroxylamine or simple heating of the enzyme to 50 °C are immunologically characterized. As a consequence of such treatment considerably less antibodies are adsorbed. The strongest influence exerts a treatment with o-(p-nitrophenyl)-hydroxylamine with simultaneous heat treatment of the enzyme for 20 min at 50 °C.
Description of Cell Adhesion by the Langmuir Adsorption Isotherm
Authors: Eckl Karl , Gruler Hans 
Published: August 2018

Abstract
The adhesion of granulocytes to a glass surface is both theoretically and experimentally investigated. The basic results are: (i) The adherence process of cells to a surface can be described by the Langmuir adsorption isotherm which also holds for the adsorption of molecules to a substrate. (ii) The granulocytes do not interact with each other during the adsorption/desorption process. (iii) The equilibrium constant at 37 °C for granulocytes adsorption to the glass surface is 170 cells/mm3 = 1.7 × 105 cells/ml. (iv) The equilibrium constant increases with decreasing temperature, (v) The equilibrium constant is a function of the chemokinetic/chemotactic stimulus f-Met-Leu-Phe. (vi) The desorption rate is also a function of the chemokinetic/chemotactic stimulus (kde
-1 = 71.5 min for 1 nᴍ and 330 min for 1 μᴍ f-Met-Leu-Phe). (vii) The adsorption rate is a function of the chemokinetic/chemotactic stimulus and the cellular bulk concentration (kad
-1- · cv
-1 = 104 min for 1 nᴍ and 8 min for 1 μᴍ f-Met-Leu-Phe, and cv = 4000 cells/mm3 = 4 × 106 cells/ml), (viii) The total number of cells which can bind to the surface is independent of temperature (and of the chemokinetic/chemotactic stimulus), (ix) The high affinity receptor site is responsible for the adherence (Kf-Met- = 1.8 nᴍ f-Met-Leu-Phe). (x) The chemokinetic/chemotactic stimulated adherence is a cooperative process on a molecular level, (xi) The cellular adsorption/desorption process is a rate controlled process. The thermodynamic description of the adsorption/desorption process failed.
Rare Eugenol-and Z-Coniferyl Alcohol Derivatives in Roots of Three Coreopsis Species
Authors: Thron U. , Martin R. , Reichling J. 
Published: August 2018

Abstract
Roots of three species of the genus Coreopsis (Compositae), C. tinctoria, C. lanceolata and C. grandiflora were investigated for the occurrence of phenylpropanoids. In addition to phenylpropanoids already known from other Coreopsis species some new derivatives of eugenol- and Z-coniferyl alcohol were found. In this report we present their structures together with their 1H NMR. 13C NMR and MS data. Two aromatic acetylenes - one of them not previously described for Coreopsis species - were identified as well.
Evidence for the Generation of Singlet Molecular Oxygen during Dopa and Dopamine Peroxidation
Authors: Kruk Irena , Lichszteld Krzysztof , Michalska Teresa , Bounias Michel 
Published: August 2018

Abstract
Participation of singlet molecular oxygen (1O2) in peroxidation of dopa and dopamine was studied by measurements of chemiluminescence spectra, the influence of solvents with various lifetime of O2 (1Δg) and O2 (1Δg)-quenchers on quantum yield of chemiluminescence.
A decrease of absorption and fluorescence intensities of 1,3-diphenylizobenzofuran (DPBF) was also studied in the presence of dopa and dopamine oxidized with alkaline H2O2 as a criterion for the involvement of 1O2.
Inhibition of Bacteriochlorophyll Biosynthesis by Gabaculin (3-Amino, 2,3-dihydrobenzoic Acid) and Presence of an Enzyme of the C5-Pathway of δ-Aminolevulinate Synthesis in Chloroflexus aurantiacus
Authors: Kern Monika , Klemme Jobst-Heinrich 
Published: August 2018

Abstract
Biosynthesis of bacteriochlorophyll c and a in the thermophilic phototrophic prokaryote. Chloroflexus aurantiacus Ok-70-fl, was strongly inhibited by the antibiotic gabaculin (3-amino 2,3- dihydrobenzoic acid), an inhibitor of the glutamate-C5-pathway of ö-aminolevulinate (ALA) synthesis. The key enzyme of the Shemin-pathway of ALA formation, ALA synthase (EC 2.3.1.37), was not detected in cell extracts of Chi. aurantiacus. However, the extracts catalyzed ALA formation from glutamate 1-semialdehyde, a reaction being highly sensitive to gabaculin.
Quantitative Structure Activity Relationships of Fungicidally Active Triazoles: Analogs and Stereoisomers of Propiconazole and Etaconazole Quantitative Structure Activity Relationships of Fungicidally Active Triazoles: Analogs and Stereoisomers of Propiconazole and Etaconazole
Authors: Ebert E. , Eckhardt W. , Jäkel K. , Sozzi D. , Vogel C. , Moser P. 
Published: August 2018

Abstract
The preparation of the four stereoisomers of propiconazole (TILT®) is described. Their inhibition of the 14α-C-demethylation of the sterol nucleus is examined and compared with the inhibition by the four stereoisomers of etaconazole (SONAX®). The quantitative structure-activity relationships (QSAR) of substituted 1,3-dioxolane-2-yl-methyltriazoles and 1,3-dioxane-2-ylmethyltriazoles on in vivo fungicidal activity are investigated.
The Effect of Bialaphos on Ammonium-Assimilation and Photosynthesis I. Effect on the Enzymes of Ammonium-Assimilation
Authors: Wild Aloysius , Ziegler Christine 
Published: August 2018

Abstract
In this investigation, the effect of bialaphos (phosphinothricyl-alanyl-alanine) on the enzymes involved in NH4
+-assimilation - glutamine synthetase, glutamine-2-oxoglutarate aminotransferase, glutamate dehydrogenase - is examined and compared to the effect of phosphinothricin (glufosinate) on the same enzymes. Bialaphos was given to whole plants (in vivo) and to leaf homogenate (in vitro).
The investigation showed that bialaphos has an inhibiting effect on glutamine synthetase in vivo, but not in vitro. In contrast to this, phosphinothricin inhibits glutamine synthetase in vitro as well as in vivo. It was found that bialaphos, similar to phosphinothricin, does not inhibit glutamine-2-oxoglutarate aminotransferase and glutamate dehydrogenase in vivo or in vitro. Only at bialaphos concentrations exceeding 10 mM, there is an inhibition of glutamate dehydrogenase in vitro.
Using radioactive [3H]bialaphos (phosphinothricyl-3H-alanyl-alanine) it could be demonstrated that in the plant, bialaphos is split into phosphinothricin and alanine. The phosphinothricin released is probably the active herbicide component. Consequently, the herbicidal effects of phosphinothricin and bialaphos are the same.
Non-Enzymatic Isomerization of 12-Hydroxy-(3Z)-dodecenal to the (2JE)-Isomer after Enzymatic Cleavage of 13-HydroperoxylinoIeyl Alcohol in Tea Chloroplasts
Authors: Hatanaka Akikazu , Kajiwara Tadahiko , Matsui Kenji , Matsunaga Tomohiko 
Published: August 2018

Abstract
Incubation of synthetic 12-hydroxy-(3 Z)-dodecenal (3 ZHD) with tea chloroplasts revealed that 12-hydroxy-(2 E)-dodecenal (2 EHD) was the product of isomerization reaction of 3 ZHD during the incubation. The isomerization was caused also by incubation of 3 ZHD with the heat-inactivated chloroplasts. The isomerization activity was extracted with hot ethanol. These results indicate that the isomerization was caused by heat-stable factor(s) but not by enzyme(s) in tea chloroplasts.
Archaebacterial Citrate Synthases: The Enzymes from the Thermoacidophiles Sulfolobus acidocaldarius and Thermoplasma acidophilum Show pro-S Stereospecificity
Authors: Müller Hans-Dieter , Görisch Helmut 
Published: August 2018

Abstract
Citrate synthase from the thermoacidophilic archaebacterium Sulfolobus acidocaldarius was purified 365-fold to electrophoretic homogeneity. At 40 °C and pH 8.1 the homogeneous enzyme shows a specific activity of 73 units per mg, which corresponds to a turnover number of 44 sec-1. Citrate synthase from S. acidocaldarius shows pro-S stereospecificity, as is found with a partially purified preparation of the enzyme from Thermoplasma acidophilum, another thermoacidophilic archaebacterium.
Interrelationship of Oxygen and Nitrogen Metabolism in the Filamentous Cyanobacterium Oscillatoria chalybea
Authors: Bednarz J. , Höper S. , Bockstette M. , Bader K. P. , Schmid G. H. 
Published: August 2018

Abstract
Filamentous Cyanobacteria. Hydrogen Peroxide, Photosystem II. Nitrogen Metabolism By means of mass spectrometric analysis we have been able to demonstrate H 20 2-production and its decomposition by photosystem II in thylakoids of the filamentous cyanobacterium Oscil­ latoria chalybea. This H2O2-production and its quasi simultaneous decomposition by the S-state system can be readily demonstrated in flash light illumination (K. P. Bader and G. H. Schmid, Biochim. Biophys. Acta 936, 179-186 (1988)) or as shown in the present paper in continuous light at low light intensities. These light conditions correspond essentially to the culturing condition of the organism on nitrate as the sole nitrogen source. Under these conditions, however, electron transport between the two photosystems seems to be mostly disconnected and respiratory activity practically non existent. Under these conditions, on the other hand, nitrate reductase is induced and nitrate reduced. The present paper addresses the question how this organism might solve the metabolic problems of nitrate reduction with such an electron transport system. Tested under high light intensities under which the organism would not grow at all, electron transport between the two photosystems is optimally linked and the system funnels part of its photosynthetically pro­duced electrons into a conventional cyanide-sensitive respiratory electron transport chain and even into an alternative Sham-sensitive (cyanide-insensitive) respiratory chain. This is made possible by the overweight of photosystem II capacity in comparison to photosystem I activity as reported in this paper. Under the conditions described, the cyanobacterium grows also on ar­ginine as the sole nitrogen source. Most interestingly under these conditions nitrate reductase induction is not shut off as is the case with other aminoacids like ornithine or alanine in the medium. Nitrite reductase is not induced in these bacteria, if grown on arginine as the sole nitrogen source. This observation is discussed in context with the fact that arginine is a major storage product (cyanophycin) in this organism and that the observed photosystem II mediated H2O2-production might be correlated with arginine metabolism.
Flower Induction in Seedlings of Asparagus officinalis L. by N-Phenylcarbamates
Authors: Yanosaka Keiko , Iwamura Hajime , Fujita Toshio 
Published: August 2018

Abstract
A series of N-phenylcarbamates induced flowers in one-month-old seedlings of Asparagus officinalis L. Ninety to 100% of the plants flowered when the seeds were germinated in the presence of the most potent members of this class. The flowering occurred only once at the top of the seedlings, which then continued to grow normally. This made it possible to select the commer­cially preferred m ales of this dioecious plant at the seedling stage. Both male and female flowers were fertile, so cross-breeding was possible between flowering seedlings as well as between flowering seedlings and adults that had grown normally. Activity of flowering induction was not related with inhibition of photosystem II activity.
The Short-Term Effects of Inorganic Phosphate on the Levels of Metabolites in Suspension-Cultured Catharanthus roseus Cells
Authors: Kubota Kaoru , Li Xiao-Ni , Ashihara Hiroshi 
Published: August 2018

Abstract
In order to analyze the effects of inorganic phosphate (Pi) on the energy metabolism of suspen­sion-cultured cells of Catharanthus roseus, short-term changes in levels of glycolytic metabolites were monitored after the addition of 1.25 mм Pi to cultures of cells previously cultured in a Pi-free Murashige-Skoog medium for 24 h. The levels of all phosphorylated intermediates of glycolysis examined were found to increase after addition of Pi. The most striking increases were observed in levels of glucose-6-phosphate and fructose-6-phosphate which rose to approximately 8 (after 30 min) and 15 times (after 120 min) their initial values. The levels of ATP and pyrophosphate doubled during the first 30 min of incubation. In contrast, the level of pyruvate decreased significantly during the initial 30 min and then began to increase again for the next 90 min. The short­ term effects of Pi on the rates of synthesis of proteins and RNA were estimated from the rates of incorporation of 14C-labelled amino acids and uridine into the macromolecules. No appreciable stimulation of the synthesis of proteins and RNA was induced by Pi within 120 min after the addition of Pi. Possible mechanisms are discussed that may be involved in the changes in metabo­lism initiated by the addition of Pi to the cultures.
Notes: Separation of 13-and 9-Hydroperoxide Lyase Activities in Cotyledons of Cucumber Seedlings
Authors: Matsui Kenji , Shibata Yasushi , Kajiwara Tadahiko , Hatanaka Akikazu 
Published: August 2018

Abstract
In cucumber cotyledons, both C6
- and C9- aldehyde were formed via hydroperoxide (HPO) lyase activity. Because it has not been elucidated whether these activities are attributed to one enzyme which can cleave both 13-and 9-HPO or to two or more enzymes each of which specifically cleaves 13-or 9-HPO , an attempt to separate HPO lyase activity was done. Ion exchange chromatography separated this activity into two fractions, one of which specifically cleaved 13-hydroperoxylinoleic acid and the other specifically cleaved the 9-isomer. 13-HPO-specific activity was most active at pH 8.0 and 9-HPO-specific one was at pH 6.5. SH -reagents inhibited both the lyases but to different extents.
Cyanoacrylate Inhibitors as Probes for the Nature of the Photosystem II Herbicide Binding Site
Authors: Huppatz John L. , McFadden Helen G. , McCaffery Leslie F. 
Published: August 2018

Three series of phenyl-substituted 2-cyanoacrylates were evaluated using simple quantitative structure activity relationships (QSAR) in an attempt to elucidate the nature of the regions of the binding site occupied by different parts of the molecules.
Inhibition of the Hill reaction by substituted 3-phenylamino-2-cyanoacrylates correlated well with the lipophilicity of the substituent. The hydrophobic effect was also dominant when the Hill activity of a series of 3-benzylamino-2-cyanoacrylates was analyzed, although potency was considerably higher in the latter series.
Lipophilicity and the electronic nature of the substituents were not major determinants in the Hill inhibitory activity of a series of substituted phcnoxycthyl 2-cyanoacrylic esters. In this case, a significant correlation was found with the molar rcfractivity (MR) of meta substituents, a parameter reflecting substituent size.
The results indicate that the phenyl moiety of substituted 3-phenylamino- and 3-bcnzyl- amino-2-cyanoacrylates interacts with an essentially lipophilic binding domain, though it is likely that the two series are oriented differently with the 3-bcnzylamino series able to bind with greater affinity. In the phcnoxycthyl ester series, the substituted phenyl group interacts with a different environment, wherein ortho- and we7tf-substitution is tolerated, dependent on the bulk of the substituent, but /wra-substitution is detrimental to affinity for this region of the site.
Molecular Modelling Studies on the Binding of Phenylurea Inhibitors to the D 1 Protein of Photosystem II
Authors: Bowyer John , Hilton Mark , Whitelegge Julian , Jewess Philip , Camilleri Patrick , Crofts Antony , Robinson Howard 
Published: August 2018

Abstract
A hypothetical molecular model of part of the D 1 protein of photosystem II, based on the analogous portion of the L subunit of the Rhodopseudomonas viridis reaction centre, has been used to study the binding of an extended hydrophobic phenylurea inhibitor (N,N-dimethyl-carbamoyl)4 -amino-4 ′-chloro-trans-stilbene) (I) to the QB site. The inhibitor was fitted by eye into a cleft in the site, and a limited part of the inhibitor/D 1 complex was energy minimized. The gross orientation of the inhibitor placed the dimethylurea moiety towards the predicted binding domain of the plastoquinone head group, and the stilbene moiety directed along the quinone isoprenoid side chain binding domain, suggesting a similar pathway of approach of the two molecules from the membrane into the binding site. Binding interactions of the inhibitor included hydrogen bonds to the side chain hydroxyl of ser 264 and the peptide carbonyl group of ala 251, with the side chain hydroxyl of ser 268 as an alternative ligand. Numerous hydrophobic contacts were also possible. Although phenylureas do not bind to reaction centres of Rp. viridis, many of the binding interactions to D1 could also be detected in Rp. viridis. However, the β-CH2 and δ-CO2
-groups of glu 212 in Rp. viridis are located in the corresponding region of D1 occupied by the dimethylurea moiety of the inhibitor in our model of its binding to D 1. This may explain why diuron (DCMU) does not bind to Rp. viridis reaction centres.
Differential Sensitivity of 32 kDa-D1 Protein Degradation and Photosynthetic Electron Flow to Photosystem II Herbicides
Authors: Jansen Marcel A. K. , Malkin Shmuel , Edelman Marvin 
Published: August 2018

Abstract
Degradation of the 32 kDa-D1 protein, a photosystem II reaction centre component, was studied as a function of linear electron flow in visible light in the presence of various photosys­ tem II herbicides. Under these conditions, herbicide specific effects on protein degradation were clearly evident. 32 kDa-D 1 protein degradation and electron flow between Qa and Qb proved to be only partially correlated. We conclude that inhibition of protein degradation by PS II herbicides in visible light is not simply correlated to displacement of Qb.
A Rapid Method for Partial mRNA and DNA Sequence Analysis of the Photosystem II psbA Gene
Authors: Naber Dirk , Johanningmeier Udo , van Rensen Jack J. S. 
Published: August 2018

Abstract
Single amino acid substitutions in the D1 protein of photosystem II may cause resistance to various herbicides. In all organisms studied these substitutions are located in or between helices IV and V of the protein. The increasing number of herbicide-resistant organisms necessitates development of a rapid methodology to characterize deviations from the wildtype se­ quence. Here, two procedures are described to identify mutations in the psbA gene, which is coding for D1. These procedures involve the isolation and amplification of DNA and R A and subsequent sequencing reactions without the need to clone the psbA gene. A triazine-resistant and a -susceptible biotype of Chenopodium album were used as model species. An A to G transition, giving rise to a serine to glycine mutation at position 264 in the D1 protein, is found in the resistant plant.