bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Novel Class of Complex Flavonoids from the Frond Exudate of Pityrogramma trifoliata
Authors: Dietz Volker H. , Wollenweber Eckhard , Favre-Bonvin Jean , Gómez P. Luis D. 
Published: August 2018

Abstract
Fronds of the neotropical fern Pityrogram m a trifoliata produce a farinose exudate which consists mainly of a dihydrochalcone. The structure of som e minor constituents has been elucidated by spectroscopic m ethods. They are shown to be representatives of a novel class of complex flavonoids, com posed of a flavonoid and a neoflavonoid moiety. In other terms, they are 5,7-di-hydroxy-8-cinnamoyl-4-phenyl-dihydrocoumarins. The occurence of these and closely related compounds in this fern’s exudate supports its inclusion in the genus Pityrogramma.
Chlorophyll Photobleaching and Ethane Production in Dichlorophenyldimethylurea-(DCMU) or Paraquat-Treated Euglena gracilis Cells
Authors: Elstner Erich F. , Osswald W. 
Published: August 2018

Abstract
Light dependent (35 Klux) chlorophyll bleaching in autotrophically grown Euglena gracilis cells at slightly acidic pH (6.5-5.4) is stimulated by the photosystem II blockers DCMU and DBMIB (both 10-5 м) as well as by the autooxidizable photosystem I electron acceptor, paraquat (10-3 м).
Chlorophyll photobleaching is accompanied by the formation of thiobarbituric acid - sensitive material (“malondialdehyde”) and ethane.
Both chlorophyll photobleaching and light dependent ethane formation are partially prevented by higher concentrations (10-4 м) of the autooxidizable photosystem II electron acceptor DBMIB or by sodium bicarbonate (25 mм).
In vitro studies with cell free extracts (homogenates) from E. gracilis suggest that α-linolenic acid oxidation by excited (reaction center II) chlorophyll represents the driving force for both ethane formation and chlorophyll bleaching.
Ethane formation thus appears to be a sensitive and non-destructive “in vivo” marker for both restricted energy dissipation in photosystem II and, conditions yielding reactive oxygen species at the reducing side of photosystem I.
Isolation and Characterization of a Chlorogenic Acid Esterase from Aspergillus niger
Authors: Schöbel B. , Pollmann W. 
Published: August 2018

Abstract
The isolation and characterization of a specific chlorogenic acid esterase is described. The enzyme activity is measured by determination of the hydrolysis product caffeic acid. The enzyme had been concentrated by means of ultrafiltration and column-chromatography. The pH- and temperature optimum were 6.5 and 45 °C respectively. Divalent cations were not required for the enzyme activity. As other esterases, this enzyme is inhibited by di-isopropyl-phosphorofluoridate. The Km-value is 0.70 mᴍ chlorogenic acid, the molecular weight 240000. The described enzyme is specific for chlorogenic acid.
On the other hand a typical unspecific esterase like the pig liver esterases does not split chloro­genic acid.
The isoelectric focusing reveals several isoenzymes of chlorogenase within a pI-range of 4.0-4.5.
Thymineless Death in Recombination Deficient Mutants of Escherichia coli K12
Authors: Ahmad S. I. 
Published: August 2018

Abstract
When grown in thymine-free minimal synthetic medium, thyA recA mutants of Escherichia coli K12 were comparatively more resistant and thyA recBC mutants more sensitive to thymineless death (TLD) than their respective parent strains. No excessive numbers of single-strand breaks were observed in the DNA of the recBC mutant strain starved for thymine, hence the hypersensi­ tivity for TLD in this strain was not caused by this type of DNA damage. Although experiments were performed with the same recBC mutant strain as used by earlier workers, results presented here contradict earlier findings that recBC mutants are no more sensitive and recA mutants are no more resistant to TLD.
Paraquat-Catalyzed Photodestructions in Subchloroplast Particles are Independent on Photosynthetic Electron Transport
Authors: Elstner E. F. , Lengfelder E. , Kwiatkowski G. 
Published: August 2018

Abstract
Light dependent ethane formation and chlorophyll bleaching in isolated chloroplast lamellae are enhanced by either methylviologen or α-linolenic acid. Both ethane formation and chloro­phyll bleaching are also enhanced in chloroplast particles deficient in photosynthetic electron transport, e. g. after aging, heat treatment or digitonin fragmentation. Ethane formation by sub­ chloroplast particles from endogenous substrates in the presence of methylviologen is inhibited by superoxide dismutase or by a penicillamine copper complex exhibiting superoxide dismutase activity whereas chlorophyll bleaching is enhanced by superoxide dismutase - active substances.
Maximal rates of ethane formation in subchloroplast particles are observed when more than 50% of the chlorophyll is bleached and continues after 98% chlorophyll bleaching. This result indicated that methylviologen -stimulated ethane production in subchloroplast particles is not de­pendent on photosynthetic electron transport but involves “activated oxygen” - species like the superoxide radical ion, generated by a light receptor derived from the pigmentsystem of photo­ system I or activated after its destruction.
High Performance Liquid Chromatographic Identification of Anthocyanins
Authors: Strack Dieter , Akavia Naaman , Reznik Hans 
Published: August 2018

A high performance liquid chromatographic procedure for a rapid identification of antho- cyanins is described. Besides their characteristic retention times, anthocyanins can easily be identified by an HPLC examination of the kinetics of appearance and disappearance of their partial hydrolysis products. This method is also applicable to 3-deoxyanthocyanins which is demonstrated with an extract from the fern Blechnum brasiliense.
The described method allows optimal resolution of complex anthocyanin mixtures in the fol­lowing sequence of elution: 3-sophoroside-5-glucoside; 3-rutinoside-5-glucoside; 3,5-diglucoside; 3-sophoroside; 3-galactoside; 3-glucoside; 3-rutinoside; 5-glucoside; aglycone, and finally the forms acylated with p-coumaric acid. Substitution in the B-ring of the aglycone structure is the key factor for the range of the retention time. Thus cyanidin 3,5-diglucoside elutes earlier (-38 sec) than pelargonidin 3-sophoroside-5-glucoside.
Some Aspects Concerning Conformation of Polypeptide Chains in Proteins
Authors: Gieren Alfred , Dederer Bernhard , Schanda Friedrich 
Published: August 2018

Abstract
The structure of (S)-N,N′-di-tert-butyl-2-[N-(1-phenylethyl)benzamido] malonamide contains two fragments of a polypeptide chain. This compound therefore can be taken as a model substance for details of protein conformation. In the crystalline state one peptide chain of the model molecule incorporates a hydrogen bond between two adjacent nitrogen atoms in the backbone. The acceptor for the hydrogen is the pz-orbital at the proton accepting nitrogen. The occurence of such hydrogen bonds in proteins might explain some correlations found between φ and ψ torsion angles. In addition a correlation between torsion angle ψ and the bond angle τ at Cα in the backbone of polypeptide chains could be established. The model substance also contains a “frozen” back side attack of a C = O group on the tetrahedrally coordinated Cα in analogy to the SN2 substitution reaction of the Walden inversion with a trigonal bipyramidal transition state.
3-D Analysis of the Flight Trajectories of Flies (Drosophila melanogaster)
Authors: Buelthoff Heinrich , Poggio Tomaso , Wehrhahn Christian 
Published: August 2018

Abstract
We have developed a computer system for reconstructing and analyzing three dimensional flight trajectories of flies. Its application to the study of the free flight behaviour of the fruitfly Drosophila melanogaster is described. The main results are: a) Drosophila males only occasionally track other flies; b) in such cases the fly’s angular velocity is a function of the error angle under which the leading fly is seen; c) body saccades can be demonstrated during cruising flights; d) high angular velocities are strongly correlated with low forward velocities, probably reflecting an aerodynamic constraint of flight. The 3-D technique described may provide an adequate tool for studying the organization of the systems present in flies and for relating the free flight behaviour to previous analyses of tethered flies.
Three Dimensional Structure of the Carbohydrate Moiety of a Lipopolysaccharide. Computer Calculations
Authors: Formanek Helmut , Weidner Hermann 
Published: August 2018

Abstract
The cell wall of the mutant R 595 of Salmonella minnesola contains a lipopolysaccharide in which only a trisaccharide consisting of three KDO * residues is linked to a lipid termed lipid A. Considering the sterical requirements of fourteen rotation angles, we have calculated allowed conformation of this trisyccharide unit and its linkage to lipid A. The calculations have been based on averaged crystallographic data of pyranose rings, ester-, N-acetyl-, phosphate-and carboxylgroups.
Because of considerable sterical hindrance, there are unique positions for the rotation around the axes O3-C3 of the glucosamine residue and O1-C1 of KDO residue 1 as well as for the rota­tion of the N-acetylgroup at the C2-atom of glucosamine. Similarly, the rotation angle of the carboxylgroup on KDO residue 1 and the rotation angles of the phosphategroup linked to glucos­ amine are highly restricted, while a large range of angles is allowed for the bond of the ester group to glucosamine.
Chemical sequence analysis yields two possibilities for the linkage between the KDO residues 1 and 2. Linkage of O4 of KDO 1 in equatorial position is restricted to a narrow range of angles, whereas the linkage to O4 in axial -and to O3 in axial and equatorial position is unfavourable. Furtheron chemical sequence analysis suggests two ways how to link KDO residue 1 and 3. The linkage to the oxygen atom on C7 of KDO residue 1 can be described by four, the linkage to the oxygen on C6 with three rotation angles. In either case two of the rotations are highly restricted. In the first case the two remaining angles have large rotational freedom, while the second case is sterically unfavorable.
The feasibility of the computer calculations has been demonstrated by the construction of a three-dimensional atomic model.
Stimulation of Wound Reactions in Potato Tubers by Thiabendazole
Authors: Elstner E. F. , Niehuss M. , Pils I. 
Published: August 2018

Abstract
Thiabendazole (TBZ), an antifungal and antihelmintic benzimidazole derivative, after 6 min treatment with a 0.1 mᴍ aqueous solution enhances CO2 release in intact potato tubers for up to two hours. There are also indications for a reduced water permeability of isolated periderm layers from TBZ - treated potato tubers. Potato slices (ca. 3 mm thick) or discs (with ca. 5 mm diameter) from potato slices show enhanced ethane formation after TBZ - treatment exhibiting maximal rates ca. two hours after treatment, indicating enhanced unsaturated fatty acid peroxidation. This lipid peroxidation is not enhanced by TBZ in potato homogenates or in isolated potato mitochondria. The results of this communication might partly explain macroscopically observable, preservative effects of treatment of freshly harvested potatoes by a stimulation of certain metabolic responses after mechanical wounding.
Solution Conformation of Benzimidazole Nucleosides with the Aid of Model Analogues
Authors: Kazimierczuk Zygmunt , Stolarski Ryszard , Dudycz Lech , Shugar David 
Published: August 2018

Abstract
The 4,6-dibromo-and 5,7-dibromo-derivatives of 1-β-ᴅ-ribofuranosylbenzimidazole, and the 4,6-dibromo-derivative of 1-α-ᴅ-arabinofuranosylbenzimidazole, have been synthesized by condensation of the trimethylsilylated derivative of 4,6-dibromobenzimidazole with the appro­priate protected sugar in the presence of SnCl4. Application of the fusion method led to the β-ribofuranoside of 2-methyl-5,6-dichlorobenzimidazole. Two additional analogues of the biologi­cally active ribofuranoside of 5,6-dichlorobenzimidazole, viz. the 2′,3′-O-isopropylidene and the 5′-chloro-5′-deoxy derivatives have been synthesized.
Analyses of the 1H NMR spectra of the foregoing, and of previously synthesized 5(6)-mono-halogeno and 5,6-dihalogeno derivatives, were employed to determine solution conformations of these nucleosides. Conformations of the sugar rings and exocyclic groups were evaluated from vicinal proton-proton coupling constants, as for purine nucleosides. The conformation of the benzimidazole ring about the glycosidic bond was determined from the chemical shifts of the sugar protons, principally H(2′), with the aid of model analogues in fixed syn and anti conforma­tions; and, independently, from the chemical shifts of the benzimidazole ring protons, principally H(4) and H(7). The halogenated benzimidazole ribofuranosides exhibit conformations of the sugar ring similar to those for purine β-nucleosides, but differ from the latter in their preference for the conformation syn about the glycosidic bond.
Rotation of Cells in an Alternating Electric Field: the Occurrence of a Resonance Frequency
Authors: Zimmermann U. , Vienken J. , Pilwat G. 
Published: August 2018

Abstract
Cells suspended in a low-conducting medium were exposed to an alternating electric field whose frequency was altered between 1 kHz and 2 MHz. A resonance frequency was observed at which all suspended cells rotated about an axis normal to the field lines (when the electric field strength was larger than a threshold value of about 400 V/cm). This resonance frequency varied from species to species of cells (mesophyll protoplasts of Avena sativa = 20-40 kHz, human erythrocytes and ghost cells = 80-100 kHz, yeast cells = 140-180 kHz, Friend cells = 30-40 kHz, at room temperature).
The resonance frequency of cell rotation was observed only under specific experimental conditions which excluded interference by reversible electrical breakdown of cell membranes and by gravitational forces.
Glutardialdehyde fixed and heated cells exhibited no rotation in the frequency and field range investigated.
The phenomenon of rotation is discussed in terms of dipole orientation within the membrane.
Properties of an ATP-Fueled, Cl--Dependent Proton Pump Localized in Membranes of Microsomal Vesicles from Maize Coleoptiles
Authors: Hager A. , Helmle M. 
Published: August 2018

Abstract
Vesicles prepared from the microsomal membrane fraction of maize coleoptiles possess an ATP-fueled H+-transport into the vesicles. It is highly possible that the vesicles from the microsomal membrane fraction actually are unchanged, native vesicles (originating from the ER or Golgi-apparatus) that can fuse with the plasmalemma or the vacuole. Therefore, they can reflect properties of the vacuole or the plasmalemma.
The energy dependent acidification within the vesicles, which can be completely reverted through the addition of CCCP, was determined on the basis of photometric difference spectra using NR (Hager et al., Z. Naturforsch. 35 c, 794-804 1980).
The proton pumps possess a very high substrate specificity; only ATP (+ Mg2+) can be used as substrate, while GTP, ITP, UTP and CTP or other nucleoside tri- or diphosphates cannot be used.
DCCD and DES inhibit H+-ATPase completely, oligomycin has only a slight, orthovanadate no inhibitory effect at all.
The energy dependent transport of H+ across the membrane takes place only in the presence of Cl- or Br- (not as well in the presence of I-). Other anions (F-, NO-
3, SO2-
4, SCN-, IDA-, H2BO-
3 cannot cause an intravesicular acidification through ATP if chloride (or Br-) is not present.
In the presence of chloride, however, some of these anions inibit the H+/Cl--symport (J-, NO-
3, SO2-
4, SCN-, H2BO-
3). They obviously are in competitive interaction with Cl- ions for Cl--binding sites on a carrier or channel without being able to be transported themselves.
Pi, which renders the acidification of the vesicles at a low rate possible without Cl-, is the only tested anion which can augment the Cl- dependent acidification.
This supports the idea that either Pi functions as a positive effector on the Cl-transport or that a Cl-/Pi-antiporter exists which reduces Cl- accumulation and therefore facilitates the Cl- coupled H+ transport into the vesicles also.
The anion transport inhibitor, DIDS, blocks the ATP-dependent H+-transport. This again supports the idea of a relatively tight coupling between H+ and Cl- transport in a possibly electroneutral system.
The presence of monovalent cations, such as K+, Na+, Li+ and choline+, are not important for H+ transport.
The dependence of the ATP-fueled acidification of the vesicles on the same anion pattern which seems to regulate elongation growth and stomata aperture speaks for the eminent importance of the H+-pump and vesicles described in this report for growth and turgor of plant cells.
Flüchtige Terpene aus Ceratocystis fimbriata Volatile / Terpenes from Ceratocystis fimbriata
Authors: Hanssen Hans-Peter , Sprecher Ewald 
Published: August 2018

Abstract
The volatile metabolites of three strains of Ceratocystis fimbriata (Ascomycetes) have been investigated. In the steam distillates of Strain 835 C several monoterpene hy­ drocarbons and alcohols as well as other metabolites could be identified. Mycelial growth and accumulation of the main components have been analyzed throughout the culture period on a defined synthetic cultural medium.
New Cembranoids from Burley Tobacco
Authors: Bruemmer Ursula , Paulsen Christian , Spremberg Gunda , Seehofer Friedlieb , Heemann Volker , Sinnwell Volker 
Published: August 2018

Abstract
The liquid CO2-extract of aged burley tobacco was investigated for its content of diterpenoids, which are considered as important precursors of flavour constituents. Among several cembranoids, already known from various tobacco types, 4,8-dimethyl-8-hydroxy-11-(1-methyl-ethyl)-14-oxo-pentadeca-5,9-diene-4-olide, a new natural product, could be identified, evidently originating from 2,6,11-cembratriene-4,8-diol by oxidative cleavage of the 11,12-double bond with subsequent cyclization to the seco-lactone 14.
Analysis of Phenolic Acids by High Performance Liquid Chromatography Using a Step-Wise Gradient
Authors: Proksch Peter , Wisdom Charles , Rodriguez Eloy 
Published: August 2018

Abstract
A high performance liquid chromatographic method for analyzing phenolic acids on reverse phase C-18 is described. Twelve substituted benzoic and cinnamic acid derivatives as well as the parent acids were resolved in less than 25 min. Separation was achieved by using a step-wise gradient of three different solvent systems and by adding ammonium acetate for preventing intramolecular hydrogen bonding of the acids.
The applicability of the described m ethod to crude plant extracts is demonstrated with Adenostoma fasciculatum, Adenostoma sparsifolium and Phyllospadix scouleri. The percent composition of the phenolic acids within the three extracts is given.
The Pressure Dependence of the Rotation of the N-Aralkyl- pyridinium Moiety in a Synthetic NAD+ Model System Studied by High Pressure HRNMR
Authors: Hauer Johann , Lüdemann Hans-Dietrich , Verhoeven J. W. 
Published: August 2018

Abstract
High Pressure, NMR, NAD +-Model, Activation Volume The activation volume ⊿V* for the rotation of the N -aralkylpyridinium moiety in a synthetic NAD + model was studied by high pressure HRNMR. From the pressure dependence of the proton spectra a negative ⊿V* of -3 cm3 · mol-1 is derived. It is concluded from this result, that the rotation of the N -aralkylpyridinium ring occurs in a complex geared m otion and not in 180°-flips.
Über die Komponenten des ätherischen Öls aus Artemisia absinthium L. / On the Essential Oil Components from Artem isia absinthium L
Authors: Vostrowsky Otto , Brosche Thorolf , Ihm Helmut , Zintl Robert , Knobloch Karl 
Published: August 2018

Abstract
By use of 13CNM R, GC and GC-MS analysis, 60 compounds, mainly mono-and sesquiterpenes, were identified structurally from the essential oil of Artemisia absinthium L. The specific appli­ cation of 13CNMR spectroscopy enabled the structure elucidation of the components. Actually for the first time trans-sabinylacetate could be identified in the essential oil from Artemisia absinthium; it even represents a main component of the oil.
Distribution of Phenylalanine Ammoma-Lyase and 4-Coumarate: CoA Ligase in Oat Primary Leaf Tissues
Authors: Knogge Wolfgang , Beulen Christa , Weissenböck Gottfried 
Published: August 2018

Abstract
4-Coumarate: CoA ligase (CL) isolated from oat primary leaves shows two activity maxim a in 5 and 7 day old seedlings, the first of which corresponds with the highest flavone accumulation rate. In this plant stage most of L-phenylalanine ammonia-lyase (PAL) is located in the epidermal tissues, whereas CL dominates in mesophyll protoplasts and in the vascular elements. In the older leaves, in which PAL is only detectable in the epiderm is and in vascular elements, most of CL is located in the latter. The CL from different tissues varies significantly in substrate specificity. Investigations of intact chloroplasts from isolated protoplasts revealed that approximately half of the PAL activity can be extracted from this organelle, whereas there is no direct evidence for the existence of CL in plastids.
A Thioredoxin Activated Glutamine Synthetase in Chlorella
Authors: Schmidt Ahlert 
Published: August 2018

Abstract
Glutamine synthetase was partly purified from Chlorella pyrenoidosa. This enzyme activity was stimulated by dithioerythritol and 2′-3′-dim ercaptopropanol (BAL). Full activation was obtained by thioredoxins isolated from the cyanobacterium Synechococcus 6301, from spinach and by heated Chlorella extract. The apparent Km for the purified thioredoxin B from Synechococcus 6301 was determined to be 0.022 (22 × 10-9 M), suggesting a specific role for thioredoxins in regulating glutamine synthetase activity in this alga.
Isolation and Partial Characterization of the Membrane-Bound NADH Dehydrogenase from the Phototrophic Bacterium Rhodopseudomonas capsulata
Authors: Ohshima Toshihisa , Drews Gerhart 
Published: August 2018

Abstract
Chemotrophically grown cells of Rhodopseudomonas capsulata contain at least three different pyridine nucleotide dehydrogenases,
i) a soluble, found in the supernatant (144000 × g) of cell free extracts, NADH-dependent,
ii) a mem brane-bound, NADH-dependent, and
iii) a soluble, found in the supernatant N AD PH dependent.
The membrane-bound NADH dehydrogenase (E.C. 1.6.99.3) has been solubilized by sodium deoxycholate treatm ent of m em branes and purified 75 fold by column chrom atography on Sephadex G-150 and DEAE cellulose in the presence of sodium cholate. The native enzyme has an apparent molecular mass (Mr) of 97 000, containing polypeptides of Mr of about 15 000. The pH optim um was at 7.5. The enzyme was specific for NADH. The Michaelis constant for NADH and DCIP were 4.0 and 63 μm, respectively.
The enzyme was inactivated by FMN, riboflavin and NADH. In contrast, the soluble NADH-dehydrogenase (i) was activated by FMN.
Structure and Biosynthesis of Vitexin 2″-O-Xyloside in Silene alba
Authors: Brederode Jan van , Kamps-Heinsbroek Ria 
Published: August 2018

Abstract
In petals of Silene alba plants of Armenian populations, vitexin 2″-O-xyloside was demonstrated to be present. The enzyme, catalyzing the transfer of the xylose moiety of UDP-xylose to vitexin, has its optimal activity at pH 7.8. Mg2+ and Mn2+ stimulated the reaction.
The Km values were 2 × 10-5 M for vitexin and 3 × 10-5 M for UDP-xylose.