bluuebunny/crossref_metadata_2025_split huggingface dataset:
Elimination of Ammonium Ion from the a-Hydroxyalkyl Radicals of Serine and Threonine in Aqueous Solution and the Difference in the Reaction Mechanism
Authors: Behrens Günter , Koltzenburg Günther 
Published: August 2018

Abstract
The zwitterionic radicals HO-ĊH-CH(COO-)NH3
+ (4a) and HO-Ċ(CH3)-CH(COO-)NH3
+ (4b) are the main species produced upon OH· radical attack in aqueous solutions at pH 3-7 at the amino acids serine, HO-CH2-CH(COO-)NH3
+, or threonine, HO-CH(CH3)-CH(COO-)NH3
+, respectively. Both radicals undergo elimination of NH4
+ ion to form the radicals O=CH-ĊH-COO- (7) or CH3-CO-ĊH-COO- (9) respectively.
The pKa of the serine-derived cationic radical HO-ĊH-CH(COOH)NH3
+ (3a) (3a ⇄ 4a + H+), was determined by ESR spectroscopy to 2.2 ± 0.1 at 276 K. From kinetic data the pKa(OH) of radical 4a (4a ⇄ O-ĊH-CH(COO-)NH3
+ (5a) + H+) was calculated to 7.0. The elimination of NH3 takes place from the ketyl radical 5a (type-B mechanism), the rate constant was calculated from kinetic data to 2.4 × 106 s-1 at 290 K.
The half-lives of radicals 4a and 4b were measured by time-resolved conductivity changes upon pulse radiolysis, 170 ± 10 μs for 4a and 26 ± 2 μs for 4b, at 290 K and pH 5.8 .
With the threonine derived radicals elimination of NH3 takes place at the stage of the α-hydroxyalkyl radical 4b (type-A mechanism). In this series the pKa of the product radical CH3-CO-ĊH-COOH (8) (8 ⇄ 9 + H+), was determined by ERS spectroscopy to 2.7 ± 0.1.
The reasons for the observed mechanistic differences (type-A versus type-B decay) are discussed. As further examples for a type-B decay some preliminary data on the elimination of HF from the radicals CF3-Ċ(OH)-CF3 and CF3-ĊH-OH have been added.
Regulation of β-Galactosidase Synthesis in Wild Type and in a Succinate-Resistant Mutant of Rhizobium meliloti
Authors: Singh A. P. , Singh J. B. 
Published: August 2018

The synthesis of β-galactosidase in Rhizobium meliloti WU60 was found to be inducible by lactose and its non-metabolizable analogue. isopropyl-β-ᴅ-thiogalactoside (IPTG). In contrast to Escherichia coli, galactose and melibiose were very weak inducers of this enzyme in R. meliloti. The maximum level of β-galactosidase in this bacterium is 2% of that in fully induced E. coli. In addition to glucose, the induced synthesis of this enzyme in R. meliloti was repressed by galactose, glycerol, and succinate. In comparison to E. coli, addition of cyclic AMP to the growth medium of R. meliloti did not alleviate the repressive effect of the above compounds on β- galactosidase synthesis.
High concentrations of sodium succinate (100 mᴍ) were inhibitory to the growth of R. meliloti. Spontaneous succinate-resistant mutants could be isolated at low frequency. In contrast to the wild type parent, in a succinate-resistant mutant, the synthesis of β-galactosidase was not repressed by succinate.
Chemiluminescence in the Coupled Oxidation of Lecithin and Ascorbate
Authors: Lichszteld Krzysztof , Machoy Zygmunt , Stępińska Anna 
Published: August 2018

Chemiluminescence (CL) that appears during oxidation of lecithin and ascorbate has been studied. A simple system consisting only of purified lecithin, which has one double bond, and ascorbate as a physiological reductant with a low redox potential, was used. The CL spectrum of lecithin contain a strong band lying in the near infrared, and three bands at 20 900 cm-1, 17 700 cm-1 and 15 800 cm-1, being characteristic of singlet molecular oxygen (1O2). The effect of 1O2 quenchers on both autooxidation processes has also been investigated. The obtained results indicate that the main emitter is the 1O2.
An addition of ascorbate to the system lecithin plus buffer causes a decrease of CL intensity. That is a result of stronger quenching properties of ascorbate and not due to efficiency of the generation of 1O2.
Flavonoids and Terpenoids from the Leaf Resin of Pluchea odorata
Authors: Wollenweber E. , Mann K. , Arriaga F. J. , Yatskievych G. 
Published: August 2018

Abstract
The chemical composition of the leaf resin of Pluchea odorata has been studied from material collected in Tamaulipas, Mexico. It mostly consists of triterpenes and phytosterols and an eudesmane type sesquiterpene. Very small amounts of ten different flavonol aglycones occur, dissolved in this resin; most of them are 6-methoxy compounds. A comparison with previous results on material from El Salvador shows that the latter contains a lesser number of triterpenes and especially of flavonoids, but more sesquiterpenes, while the n-alkane composition varies only quantitatively between both populations.
Acylchain Specificity and Kinetic Properties of Phospholipase A1 and A2 of Bone Marrow-Derived Macrophages
Authors: Flesch Inge , Schmidt Brigitte , Ferber Ernst 
Published: August 2018

Abstract
The fatty acyl specificity of phospholipase A1 and A2 in homogenates of mouse bone marrow-derived macrophages was determined using phosphatidylcholine and phosphatidylethanolamine of different acylchain composition. Phosphatidylcholine with arachidonoyl at position 2 was cleaved preferentially by an alkaline phospholipase A2 (pH-optimum 9.0) leading to selective liberation of arachidonic acid. In contrast, phosphatidylcholines with oleoyl or linoleoyl at posi­tion 2 were degraded mainly by an acid phospholipase A1 (pH-optimum 4 -5) resulting in a conservation of these fatty acids esterified in lysophosphatides. Substrate kinetics of the alkaline phospholipase A2 revealed a 30 fold higher affinity (Km = 3.8 x 10-7 ᴍ) for 1-acyl-2-arachidonoyl-glycerophosphocholine compared to 1-acyl-2-oleoyl-glycerophosphocholine. The kinetic data were not influenced by endogenous lipids indicating that exogenous substrates do not equilibrate with cellular lipids.
These results are suitable to explain a selective liberation of arachidonic acid from a mixture of phospholipids.
Prosomes are Involved in the Repression of Viral mRNA
Authors: Horsch Andrea , Köhler Kurt , Schmid Hans-Peter 
Published: August 2018

Abstract
Prosomes are small cytoplasmic RNP complexes. We present evidence that their RNA is a potential and selective inhibitor of viral mRNA translation while translation of normal cellular mRNA e.g. rabbit globin mRNA or HeLa cell mRNA is not affected.
New Flavone Glucoside Malonylesters from Bryum capillare
Authors: Stein Wolfgang , Anhut Siegbert , Dietmar H. , Mues Rüdiger , Barz Wolfgang , Köster Johannes 
Published: August 2018

Abstract
From Bryum capillare Hedw. a variety of flavone glucosides and their 6″ malonyl esters were isolated. Diosmetin 7-O-β-D-glucoside-6″-malonylester, luteolin 7-O-β-D-glucoside-6″-malonyl-ester and 6-OH-luteolin 7-O-β-D-glucoside-6″-malonylester are new flavone malonyl esters. This is the first report of flavone glucoside malonylesters in a non vascular plant. The flavonoid pattern of the gametophyte is different from that of the sporophyte. The chemotaxonomic relevance of these results is discussed.
Comparative Analysis of Epicuticular Waxes from Some High Alpine Plant Species
Authors: Lütz Cornelius , Gülz Paul-Gerhardt 
Published: August 2018

Abstract
Epicuticular waxes were extracted and analysed from leaves of 7 different high alpine plant species, with 3 species harvested at different altitudes: Salix herbacea (1950 m, 2825 m), Leucanthemopsis alpinum (1950 m, 3050 m), Loiseleuria procumbens (1950 m, 2660 m), Dryas octopetala (2400 m), Ranunculus glacialis (2800 m), Soldanella pusilla (2640 m), Oxyria digyna (2640m). Two main fractions obtained from waxes were investigated: hydrocarbons and wax-esters, -aldehydes plus -acetates. Individual wax compounds accumulated differently in the respective plant species. The gross composition did not indicate a strict altitude-dependent change in wax composition, though some single components like the C-29/C-31 alkanes (Loiseleuria) or the C-22/C-26 fatty acid methyl esters in Salix, changed significantly with increasing elevation of plant habitat. The evergreen leaves of Dryas and of Loiseleuria exhibited exceptionally high amounts of triterpenol esters.
The results indicate that the formation of epicuticular wax layers is not based on a special adaptation to altitude or high mountain habitats in general.
Biosynthetic Capacity of Stachys Seedlings for Verbascoside and Related Caffeoyl Derivatives
Authors: Andary Claude , Ibrahim Ragai K. 
Published: August 2018

Abstract
The caffeoyl derivatives of Stachys leaves (Labiateae) were identified as chlorogenic acid, verbascoside and stachyoside. The latter compound, reported here for the fist time, was shown to be a verbascoside derivative containing an extra glucose residue attached to C-2, C-3 or C-4 of rhamnose.
Cotyledonary leaves of Stachys accumulate high levels (8 -16 μmol/g dry tissue) of the three caffeoyl derivatives; all of which decrease significantly in amount during plant growth. Intact organs of the seedling were shown to efficiently incorporate the label from different precursors into caffeoyl derivatives. The biosynthesis of both verbascoside and stachyoside from labelled precursors revealed that the caffeoyl moiety was exclusively labelled from phenylalanine or cinnamic acid, whereas the 3,4-dihydroxyphenylethanol moiety was labelled from tyrosine, and better from tyramine.
Isolation and Separation of Epidermal and Mesophyll Protoplasts from Rye Primary Leaves — Tissue-Specific Characteristics of Secondary Phenolic Product Accumulation
Authors: Schulz Margot , Weissenböck Gottfried 
Published: August 2018

Abstract
We have develop ed a technique for the large-scale isolation of epidermal and mesophyll proto­plasts, as well as the vascular strands, of rye primary leaf blades.
Separation of the two types of protoplasts has been successful only from leaves harvested at the end of a 13-h light period, when chloroplasts were enriched in starch.
The occurrence of different flavonoid compounds, and amounts, in epidermal and mesophyll protoplasts can be used as criteria for protoplast purity and viability since C-glucosylflavone O-glycosides are characteristic of epidermal protoplasts whereas flavone O-glucuronides and anthocyanins are typical of mesophyll protoplasts. Several non-flavonoid phenolic compounds are found only in the epidermal protoplast. These patterns of secondary product accumulation reflect the high tissue specificity of the rye leaf.
Biosynthesis of 4-Formyl-4-imidazoIine-2-on, the Heterocyclic Base of Nikkomycin X
Authors: Schmidt Ralf-Michael , Pape Hermann , Junack Matthias 
Published: August 2018

Abstract
The nucleoside-peptide antibiotic nikkomycin X contains the unusual heterocyclic base 4-formyl-4-imidazoline-2-on. Investigations on the biosynthesis of this base were accomplished in a resting cell system which was optimized in respect to nikkomycin production.
Incorporation experiments with [2-14C]adenine, [8-14C]adenine, [2-14C]glycine, [2-14C]uracil, [U-14C]histidine, and [2-14C]histidine revealed that only [2-14C ]adenine, [U-14C]-and [2-14C]histidine were specifically incorporated into nikkomycin X. An incorporation experiment with [2-13C]adenine resulted in a 31-fold enrichment of the carbon atom 2 of 4-formyl-4-imidazoline-2-on. These results show that the heterocyclic base of nikkomycin X is a product of the histidine biosynthetic pathway.
Elicitor-Stimulated Furanocoumarin Biosynthesis in Cultured Parsley Cells: S-Adenosyl-ʟ-Methionine:Bergaptol and S-Adenosyl-ʟ-Methionine: Xanthotoxol O-Methyltransferases
Authors: Hauffe Karl Dietrich , Hahlbrock Klaus , Scheel Dierk 
Published: August 2018

Abstract
Cultured parsley cells (Petroselinum crispum) treated with an elicitor from the soybean patho­gen, Phytophthora megasperma f. sp. glycinea, were used as source for the separation, extensive purification and characterization of S-adenosyl-ʟ-methionine: xanthotoxol and S-adenosyl-ʟ-m ethionine: bergaptol O-methyltransferases. The products, xanthotoxin and bcrgapten, were among the most abundant coumarin derivatives accumulated in the culture fluid of elicitor-treated parsley cells. The latter enzyme also catalyzed the methylation of 5-hydroxyxanthotoxin to isopimpinellin, another major coumarin derivative in this system. The activities of both enzymes showed transient increases upon elicitor application prior to the accumulation of the products. No activity was detectable in untreated cells. Activity increases of the O-methyltransferases occurred a few hours later than those of phenylalanine ammonia-lyase and 4-coumarate:CoA ligase.
Flavonoid Constituents of Rhamnus lycioides L.
Authors: Payá Miguel , Máñez Salvador , Villar Angel 
Published: August 2018

Abstract
From the aerial part of Rhamnus lycioides, which is used in folk medicine in eastern Spain as an antihypertensive drug, seven free flavonoid aglycones were isolated. They were structurally eluci­dated as rhamnazin. rhamnocitrin, isorhamnetin, kaempferol, quercetin. quercetin-3-methylether and taxifolin. by applying the principal spectroscopic methods and TLC with authentic markers.
Effects of Low Frequency Magnetic Fields on Chick Embryos. Dependence on Incubation Temperature and Storage of the Eggs
Authors: Juutilainen Jukka P. 
Published: August 2018

Abstract
Chick embryos were exposed to sinusoidally oscillating 100 Hz magnetic fields during their first two days of development. The magnetic field strength was 1 A/m. Incubation temperatures of 36.3, 37.0, 38.0 and 38.5 °C were used and the duration of the storage of the eggs before incuba­tion was varied from 1 hour to 4 days. After the incubation, the embryos were examined for abnormalities. When the temperature was 36.3 or 37.0 °C and the eggs were stored for one day or less, the effect of the magnetic field was statistically significant. In these conditions, the percent­ age of abnormal control embryos was low, 8% in 36.3 °C and 5% in 37.0 °C. In the exposed groups the corresponding percentages were 23% (36.3 °C) and 25% (37.0 °C). However, higher temperature and storage of the eggs for 3 to 4 days increased the percentage of abnormal embryos in both the exposed and control groups. The difference between the exposed and control embryos was not significant in these conditions. The results demonstrate the importance of the handling of the eggs in this kind of experiments.
Changes in the Stoichiometry of Photosystem II Components as an Adaptive Response to High-Light and Low-Light Conditions during Growth
Authors: Wild Aloysius , Höpfner Matthias , Rühle Wolfgang , Richter Michael 
Published: August 2018

The effect of different growth light intensities (60 W·m-2, 6 W·m-2) on the performance of the photosynthetic apparatus of mustard plants (Sinapis alba L.) was studied. A distinct decrease in photosystem II content per chlorophyll under low-light conditions compared to high-light conditions was found. For P-680 as well as for Oᴀ and Oв protein the molar ratio between high-light and low-light plants was 1.4 whereas the respective concentrations per chlorophyll showed some variations for P-680 and Oᴀ on the one and Oв protein on the other hand.
In addition to the study of photosystem II components, the concentrations of PQ, Cyt f, and P-700 were measured. The light regime during growth had no effect on the amount of P-700 per chlorophyll but there were large differences with respect to PQ and Cyt f. The molar ratio for Cyt f and PQ between high- and low-light leaves was 2.2 and 1.9, respectively.
Two models are proposed, showing the functional organization of the pigment system and the electron transport chain in thylakoids of high-light and low-light leaves of mustard plants.
Pflanzliche Insektizide, III [1], Pyrethrin I im etherischen Öl von Chrysanthemum balsamita L. / Herbal Insecticides III [1]. Pyrethrin I in the Essential Oil of Chrysanthemum balsamita L.
Authors: Bestmann Hans Jürgen , Claßen Beate , Kobold Uwe , Vostrowsky Otto , Klingauf Fred 
Published: August 2018

Abstract
From the leaves of Chrysanthemum balsamita L. an essential oil with insecticidal properties was isolated and the components were analyzed by gas chromatography and mass spectrometry. By means of TLC and HPLC the oil was divided into several fractions, which were examined for their insecticidal activity in a biotest. The activity could be contributed to pyrethrin I which was found for the first time in C. balsamita.
Interference of Dimethazone with Formation of Terpenoid Compounds
Authors: Sandmann Gerhard , Böger Peter , Sandmann Gerhard , Böger Peter 
Published: August 2018

Abstract
Dimethazone is a bleaching herbicide without any peroxidative activity. In addition to the inhibition of chlorophylls, carotenes, and xanthophylls, decreased formation of other prenyl lipids (phytol and α-tocopherol) can be observed in the presence of dimethazone. Application of this herbicide to pea plants results in the inhibition of longitudinal growth of the newly formed internodes which can be reversed by gibberellic acid. Apparently, dimethazone also decreases the endogenous gibberellin levels.
As the formation of all the compounds assayed is inhibited to the same extent and as I50 -values for chlorophyll and carotenoid biosynthesis are identical (about 10 µᴍ dimethazone), the various effects of dimethazone are explained by a single enzyme target in the terpenoid biosynthetic pathway between acetate and geranylgeranyl pyrophosphate.
Identification and Biosynthesis of Glucosylated and Sulfated Flavonols in Flaveria bidentis
Authors: Varin Luc , Barron Denis , Ibrahim Ragai 
Published: August 2018

1.The flavonoid constituents of Flaveria bidentis have been identified as the 3-O-glucosides of kaempferol. 6-methoxykaempferol and 6-methoxyquercetin (patuletin), as well as six flavonol sulfate esters belonging to quercetin and isorhamnetin. The two latter glucosides are reported here for the first time in this species; whereas quercetin-3,7-disulfate, is a novel compound from nature.
2.The amounts of both glucosides and sulfate esters in young seedlings were highest in buds > stems > leaves on fresh weight basis, whereas they were undetectable in the root. There were striking quantitative differences in the flavonoid pattern of young seedlings, as compared with mature shoots, especially the flavonol sulfate esters which were predominant in seedlings.
3.The biosynthesis of both groups of flavonoids from [3H]cinnamate and [35S]sulfate showed that the former was predominantly incorporated into glucosides whereas the latter, into sulfate esters; thus indicating that sulfation is a later step in the biosynthesis of flavonol sulfate esters.
4.The significance of the glucosylation and sulfation reactions was discussed in relation to the regulation of biosynthesis and compartmentation of both groups of compounds.
An Elicitor of the Hypersensitive Lignification Response in Wheat Leaves Isolated from the Rust Fungus Puccinia graminis f. sp. tritici II. Induction of Enzymes Correlated with the Biosynthesis of Lignin
Authors: Moerschbacher B. , Heck B. , Kogel K. H. , Obst O. , Reisener H. J. 
Published: August 2018

The genuine biotic elicitor from germ tube walls of Puccinia graminis f. sp. tritici (Pgt-elicitor) induces lignification, preceded by an increase in phenylalanine ammonia-lyase (PAL) activity, when injected into the intercellular space of primary wheat leaves. This increase in PAL activity is accompanied by an increase in other enzyme activities of the general phenylpropanoid pathway and the specific pathway of lignin biosynthesis: 4-coumarate :CoA ligase (4CL), cinnamyl alcohol dehydrogenase (CAD) and peroxidase (PO).
Total extractable activities of 4CL, CAD and PO do not differ significantly in resistant and susceptible near isogenic wheat lines, whereas the dose response curve of induced PAL activity shows significantly higher values in the resistant isoline. This difference is not observed after injection of other biotic and abiotic elicitors of the lignification response.
Although total induced PO activities 24 h after elicitor treatment are equal in both isolines, the PO isoenzyme pattern of resistant plants differs markedly from that of susceptible plants. The patterns of PO isoenzymes in the compatible and incompatible interaction 48 h after inoculation with Puccinia graminis f. sp. tritici also show differences, which closely resemble those seen after injection of the Pgt-elicitor. The patterns observed after injection of an artificial biotic elicitor clearly differ from those of the natural interaction.
Natural Waxes Investigated by Soft Ionization Mass Spectrometry
Authors: Schulten H .-R . , Murray K. E. , Simmleit N. 
Published: August 2018

Field ionization (FI) and field desorption (FD) mass spectra of 35 aliphatic long-chain and branched long-chain compounds, representing the major six classes of constituents of natural waxes, are examined. In the FI mode the molecular ions are usually formed at comparatively low levels, while in FD such species are almost exclusively generated. In addition, some fast atom bombardment mass spectra, in the positive and negative ion mode, of selected lipids are recorded for comparison. In general, field ionization and field desorption techniques are found to be superior for mass spectrometric studies of low-polarity compounds.
Examination of several natural waxes, such as Jojoba wax, preen gland wax of goose, beeswax and epicuticular wax of Norway spruce, shows that field desorption mass spectrometry has a most promising role in the characterization of wax components. The intense molecular ions allow the identification of the constituents of complex lipid mixtures without the need for derivatization. Thus, for the first time, the carbon number distribution, especially of the high-mass wax con­stituents can be established for the natural waxes investigated. For identification of high-mass wax constituents the present results suggest that field desorption mass spectra could be best employed in conjunction with class and individual separation of constituents by chromatographic proce­dures.
The analysis of natural waxes is nowadays of major concern because of its importance in the problem of forest damage.
Derepression of Arylsulfatase Activity by Sulfate Starvation in Chlorella fusca
Authors: Niedermeyer Inge , Biedlingmaier Susanne , Schmidt Ahlert 
Published: August 2018

Abstract
Arylsulfatase activity was detected in the green alga Chlorella fusca 211-8b during sulfur starvation. No activity was present during growth on sulfate, whereas activity was found with sulfur sources as growth-limiting factor including L-cysteine and L-methionine. Arylsulfatase activity was found after transfer to sulfate starvation conditions after a lag-period of about 3 h; addition of cycloheximide prevented arylsulfatase formation, suggesting the participation of protein synthe­ sis. Addition of sulfate to cultures with active arylsulfatase led to a decay of this enzyme, whereas addition of sulfate and cycloheximide prevented this decay suggesting that protein synthesis is also needed for degradation of arylsulfatase activity. The Km for p-nitrophenyl sulfate was determined to be 0.8 mм. The activity of the arylsulfatase is not affected by sulfate or phosphate, however it is inhibited strongly by sulfite, cyanide and boric acid and therefore is classified according to Dogson and Spencer (Meth. Biochem. Anal. 4, 211-254 (1957) as an arylsulfatase of type I.