bluuebunny/crossref_metadata_2025 huggingface dataset:
Selective binding of amino acid residues to trna molecules detected by anticodon-anticodon interactions
Authors: Bujalowski W. , Porschke D.
Published: August 2018

Anticodon-anticodon pairing of complementary tRNA’s has been studied by fluorescence temperature jump measurements in the presence of different ligands as an approach for the evaluation of ligand binding to tRNA. This procedure is particularly useful for ligands which do not show spectroscopic changes upon binding, but affect the pairing potential of anticodons. Addition of phenylalanine-, tyrosine- and tryptophan-amide leads to a substantial decrease of the tRNAPhe-tRNAGlu pairing constant Kp, whereas Kp remains almost unaffected by addition of leucine amide and increases upon addition of glycine amide. The effects observed for the aromatic amino acid amides can be described quantitatively by a site binding model with preferential binding of the amides to tRNAPhe. The binding constants evaluated according to this model (Pheamide 120 M-1, Tyr-amide 160 M-1 and Trp-amide 580 M-1) are consistent with values obtained independently by fluorescence titrations with tRNAPhe. Selective binding of these amino acid residues to tRNAPhe is deduced from the observed concentration dependence, which is not compatible with a corresponding binding process to tRNAGlu. Addition of glutamic acid diamide induces an increase of the tRNAPhe • tRNAGlu pairing constant, which is however equivalent to that observed for tRNAPhe-tRNALys pairing and thus does not demonstrate a selective binding to tRNA °1 u . The pairing of tRNAPhe with tRNAGlu is strongly enhanced by addition of Mg2+ or spermine. Evaluation of the Mg2+ data by a site model leads to constants of 360 M-1 for the binding of Mg2+ to monomer tRNA and 3000 M-1 for the binding of Mg2+ to the tRNAPhetRNAGlu dimer. A comparison of the enhanced pairing observed in the presence of Mg2+, which is known to induce a 3′-stack conformation of the anticodon loop, with the reduced pairing affinity observed in the presence of aromatic amino acid amides suggests induction of a 5′-stack conformation by the latter ligands
Apomorphine and haloperidol influence electric behaviour of a mormyrid fish
Authors: Kunze Peter , Wezstein Hans-Ulrich
Published: August 2018

The electric behaviour of the mormyrid Gnathonemus petersii is changed by dopaminergic drugs applied to the aquarium water. The upper limit of the interpuis interval distributions is significantly shifted to shorter intervals by apomorphine-HCl (.082-,328 mg/ml), and to longer intervals by haloperidol (.041 -.164 mg/ml). The effect of apomorphine is antagonized by haloperidol. Probably, a dopamin system is involved in the neural control of the electric organ
Organ Specific Composition of Epicuticular Waxes of Cistus albidus L., Cistaceae
Authors: Hennig Sabine , Gülz Paul-Gerhard , Hängst Kurt
Published: August 2018

Epicuticular waxes from various organs of Cistus albidus L. showed always an organ specific composition.

Leaf wax contained homologous series of very long chained and saturated wax components, such as hydrocarbons, wax esters, fatty acids and alcohols. Additionally in this wax extract triterpenoids and great amounts of resin were found. Sepal wax had nearly the same wax composition like that of leaves with a trend to shorter chain lengths and not so great amounts of resin.

Petal wax contained the common wax lipids, too, but the homologous series showed a shift to shorter chain lengths, and great amounts of unsaturated lipids were found in hydrocarbons, wax esters and fatty acids. In addition triterpenol esters were found but no resin.

Stamen wax was similar to that of petals. The shift to shorter chain lengths and the presence of great amounts of unsaturated lipids showed a characteristic distribution for stamens.

Seed wax contained only saturated wax lipids. In contrast to leaf waxes, the short chain compounds were dominating, and triterpenoids and resin were missing.

The chemical wax composition of the various organs of C. albidus was correlated to the surface structures of these organs by SEM pictures.
Structure-Activity Relationships and Physiological Aspects of New Photosynthetic Electron Transport Inhibitors, 3-Alkylaminoalkyliden-2H-pyran-2,4(3H)-diones (APs)
Authors: Asami Tadao , Koike Hiroyuki , Inoue Yorinao , Takahashi Nobutaka , Yoshida Shigeo
Published: August 2018

3-Aminoalkylidene-2H-pyran-2,4(3H)-diones (APs), possessing a conjugated enamino moiety which is common to cyanoacrylates and 2-aminoalkylidenecyclohexane-1,3-diones (ACs), were found as a new class of photosynthetic electron transport inhibitors. Although the structural requirement of APs for photosynthetic electron transport inhibition was very similar to that of cyanoacrylates and ACs, thermoluminescence measurements indicated that the binding manner of APs to D 1 protein was totally different from that of other inhibitors.
Accumulation of a Novel Red Pigment in Cell Suspension Cultures of Floral Meristem Tissues from Carthamus tinctorius L.
Authors: Saito Koshi , Daimon Etuko , Kusaka Kazuhito , Wakayama Sachio , Sekino Yoshihiro
Published: August 2018

A cell strain originally derived from floral meristem tissues of Carthamus tinctorius (dyer’s saffron) produced substantial amounts of a novel red pigment under controlled culture conditions. The pigment isolated f r om alcoholic extracts of C. tinctorius cultures was compared with authentic carthamin, anthocyanins, betain, and carotenoids. It differed markedly from carthamin and showed none of the characteristic properties of the glycoside or chloride forms of authentic delphinidin, cyanidin, and pelargonidin. Analytic data indicated that this pigment also differs from betanin and from α- and β-carotene. The name “Kurenamin” was tentatively given to this newly isolated red pigment. Effect of the culture media, micro-elements, macro-elements, and putative substrates on the kurenamin production were investigated during cell suspension culture.
Photoinhibition of Electron Transport Activity of Photosystem II in Isolated Thylakoids Studied by Thermoluminescence and Delayed Luminescence
Authors: Vass Imre , Mohanty Narendranath , Demeter Sándor
Published: August 2018

The effect of photoinhibition on the primary (QA) and secondary (QB) quinone acceptors of photosystem I I was investigated in isolated spinach thylakoids by the methods of thermoluminescence and delayed luminescence. The amplitudes of the Q (at about 2 °C) and B (at about 30 °C) thermoluminescence bands which are associated with the recombination of the S2QA
- and S2QB charge pairs, respectively, exhibited parallel decay courses during photoinhibitory treatment. Similarly, the amplitudes of the flash-induced delayed luminescence components ascribed to the recombination of S20A and S2OB charge pairs and having half life-times of about 3 s and 30 s, respectively, declined in parallel with the amplitudes of the corresponding Q and B thermoluminescence bands. The course of inhibition of thermoluminescence and delayed luminescence intensity was parallel with that of the rate of oxygen evolution. The peak positions of the B and Q thermoluminescence bands as well as the half life-times of the corresponding delayed luminescence components were not affected by photoinhibition. These results indicate that in isolated thylakoids neither the amount nor the stability of the reduced OB acceptor is preferentially decreased by photoinhibition. We conclude that either the primary target of photodamage is located before the O b binding site in the reaction center of photosystem II or QA and OB undergo simultaneous damage.
Dark and Photohemolysis of Erythrocytes by Furocoumarins
Authors: Vedaldi Daniela , Caffieri Sergio , Miolo Giorgia , Dall'Acqua Francesco , Arslan Paola
Published: August 2018

It has been shown that various furocoumarins are able to cause dark hemolysis in red blood cells (RBC). However, this effect is evident only at relatively high furocoumarin concentrations (4.6 x 10-4 M) - much higher than those used in photosensitization experiments or photochemotherapeutic treatments.

Among the various furocoumarins examined in this study, only psoralen (Ps) and 3-carbethoxypsoralen (3-CPs) showed strong photohemolytic effects, while the other compounds revealed little or no activity. This fact indicates that Ps and 3-CPs are able to induce selective damage to the cell membrane of RBC.

By pre-irradiating furocoumarin in ethanol or isotonic saline solutions and adding the irradiated solutions to a RBC suspension, hemolysis was observed in various compounds. The products of photolysis which form during pre-irradiation may be responsible, in terms of hemolysis, for toxic effects on RBC.
Stabilität des Ferricinium-Kations und seine cytostatische Wirkung / Stability of Ferricinium and its Cytostatic Effect
Authors: Wenzel M. , Wu Y. , Liss E. , Neuse E. W.
Published: August 2018

The relative stabilities of different ferricinium cations were studied in buffer or serum-containing solution and in vivo and compared with their cytostatic effects in cultures of Yoshida ascites tumor cells.

Although the ferricinium cation itself was the most unstable cation compared with the dimethyl-ferricinium cation and the deuterated ferricinium derivatives it showed the highest cytostatic effect.
Enzymatic Conversion and Degradation of Sex Pheromones in Antennae of the Male Silkworm Moth Antheraea polyphemus
Authors: Kasang Gerhard , Proff Leopold von , Nicholls Michael
Published: August 2018

In living antennae of the male silkworm moth Antheraea polyphemus the pheromone compounds [6,7-3H]-6,11-hexadecadienyl acetate and [12,13-3H]-10,12-hexadecadienol are enzymatically converted to their corresponding fatty alcohols, aldehydes, acids and long-chained fatty acid esters. In antennae of freshly hatched moths the 3H-labeled pheromones are degraded at high rates to volatile polar metabolites. The half-life of the pheromone acetate is about 3 min. In dried antennae the pheromone acetate is merely hydrolyzed to the fatty alcohol.
Three New Benzoic Acid Derivatives from the Glandular Excretion of Eriodictyon sessilifolium (Hydrophyllaceae)
Authors: Arriaga-Giner Francisco J. , Wollenweber Eckhard , Schober Ingrid , Yatskievych George
Published: August 2018

Eriodictyon sessilifolium, an endemic Hydrophyllaceae of Baja California (Mexico), has been studied for the natural products exuded by glandular trichomes covering its leaves and stems. Major components of this exudate were isolated and identified by spectroscopic methods to be 4-hydroxy-3-(2,3-dihydroxy-3-methylbutyl)-benzoic acid methyl ester (1), the natural methyl ester of anodendroic acid (2), and 2,2-dimethyl-3-hydroxychroman-6-carboxylic acid methyl ester (3). Possible biosynthetic relations between these new natural products are considered. In addition, 9 known flavonoid aglycones were identified as exudate constituents.
Effect of Chlorsulfuron, a Potent Inhibitor of Acetohydroxyacid Synthase, on Metabolism of Claviceps purpurea
Authors: Maier Walter , Schumann Brigitte , Gröger Detlef
Published: August 2018

Chlorsulfuron (CS) is a potent sulfonylurea herbicide inhibiting specifically acetohydroxyacid synthase which catalyzes the first step in the biosynthesis of branched-chain amino acids in plant cells, bacteria and yeast. The peptide portion of some ergot alkaloids contain inter alia branchedchain amino acids. The influence of CS on growth and alkaloid formation in Claviceps was studied. In an ergotoxine strain growth is inhibited by chlorsulfuron in the range of 10-100 μᴍ. Under CS influence ergosine is accumulated besides ergotoxines. Growth inhibition caused by CS could be reversed by addition of ʟ-valine ( ~ 35 mᴍ), but neither by leucine nor isoleucine. Ergosine did not occur under these conditions. Acetohydroxyacid synthase (AHAS) from Claviceps purpurea was partially purified. AHAS preparations are not inhibited even by high concentrations of chlorsulfuron.
Pflanzenabwehrstoffe XXXIV [1]. Synthese der 2-(E)-O-(4-Hydroxy-cinnamoyI)-ᴅ,ʟ-galactarsäure, eines vermeintlich photosensitiven Faktors aus Glycine max / Synthesis of 2-(E)-O-(4-Hydroxy-cinnamoyl)-ᴅ,ʟ-galactaric Acid, a Presumptive Photosensitive Factor from Glycine max
Authors: Schildknecht Hermann , Sauer Horst , Kunzelmann Peter
Published: August 2018

The synthesis of 2-(E)-O-(4-hydroxy-cinnamoyl)-ᴅ,ʟ-galactaric acid (1a) is described. Starting with free galactaric acid (2) and 4-acetoxy-cinnamoyl-chloride (3), these compounds were esterified under regioselective conditions to racemic 2-(E)-O-(4-acetoxy-cinnamoyl)-galactaric acid (4). After deprotection of the p-coumaroyl moiety 1a was obtained as a photo-unstable product. Optical resolution of racemate l a on bovine serum albumin covalently bound to silica resulted in the isolation of the pure optical isomers. The (+)-dextrorotatory synthetic enantiomer l a proved to be identical with the natural factor.
Distribution of cis-trans-β-Carotene in Pigment-Protein Fractions of Photosystem I and II
Authors: Brody S. S. , Simpson D. , Rieh M.
Published: August 2018

The distribution of isomers of β-carotene is reported in the CP-47 pigment-protein complex of photosystem II and photosystem I (PS I) from barley. The distribution of carotenoids from light harvester complex I I is reported. CP-47 lacks 9,9′-rá-carotene, but contains 9,13′-cis-carotene; PS I lacks 9,13′-cis but contains 9,9′-eis. More 9-cis, 9,13-cis, 9,15-cis, and epoxide is observed in CP-47 than in PS I.
Diskriminierungspheromone der sozialen Wüstenassel Hemilepistus reaumuri / Discriminative Pheromones of the Social Desert Isopod Hemilepistus reaumuri
Authors: Schildknecht Hermann , Eßwein Ulrike , Hering Werner , Blaschke Christine , Linsenmair Karl Eduard
Published: August 2018

A vital chemical communication can be observed in the Tunesian desert isopod Hemilepistus reaumuri. These crustaceans live in social units which are strictly closed to alien conspecifics. It was attempted to analyze the highly evolved family-specific recognition system by identifying their pheromonal compounds both from the extracts of surface washings of intact animals and from the exuvia.
The Role of Dorsal Rim Ommatidia in the Bee's Eye
Authors: Kirschfeld K.
Published: August 2018

A recent model of celestial e-vector analysis by the bee assumes that polarization information is transformed into modulation of perceived brightness while the bee scans the sky by rotating its field of view. It is shown that the suggested simple strategy to read compass information from the polarization pattern of the sky in natural conditions can work only in a part of the sky close to the zenith. The bee would need a different strategy for other regions of the sky.
Purification and Characterization of Calcium-Activated Neutral Proteinase from Calf Thymus
Authors: Schwenk Manfred , Zoch Erwin
Published: August 2018

A calcium-activated neutral proteinase (CANP) was prepared from the soluble fraction of calf thymus and purified to electrophoretical homogeneity. The purified proteinase was shown to consist of two subunits, each of 80 kDa, in contrast to rabbit skeletal muscle calpain which was shown to consist of 80 kDa and 30 kDa subunits. The calcium requirement for 50 % activation was 0.55 mᴍ, indicating that this enzyme belongs to the low calcium sensitive type of CANP , named mCANP or Calpain II. Optimal conditions of enzyme activity towards 0.8% casein as substrate are pH 7.5, a calcium concentration of 1.5 mᴍ, the presence of an SH-reducing agent and an incubation temperature of 30 °C. The enzyme is inhibited by Zn2+ , p-chloromercuribenzoate and N-ethylmaleimide.
QSAR of Nitro-diphenylethers as Inhibitors of Cyclic Photophosphorylation
Authors: Oettmeier Walter , Masson Klaus , Donner Andreas
Published: August 2018

A number of 25 nitro-diphenylethers have been synthesized and assayed for their inhibitory activity in N-methylphenazonium-methosulfate mediated cyclic photophosphorylation. Their pI50-values were in the range from 3.5 to 5.3. A QSAR-analysis revealed that the lipophilicity of the nitro-diphenylethers as expressed by ∑π played a major role. In addition, the Taft steric parameter Es in positions 6′, 4′ and 2′ (in decreasing order) contributed to the inhibitory activity. For maximal biological activity, positions 4′ and 6′ should be left unsubstituted whereas a bulky substituent is required for position 2′.
Mass Spectrometry Analysis of Oxygen Gas Exchange in High- and LOW-CO2 Cells of Chlorella vulgaris
Authors: Shiraiwa Y. , Bader K. P. , Schmid G. H.
Published: August 2018

Oxygen gas exchange was monitored in the unicellular green alga Chlorella vulgaris 211 - 11 h by means of a mass spectrometer equipped with a special membrane gas-inlet-system and a photosynthetic reaction vessel. CO2-dependent 18O2-uptake as well as 16O2-evolution were analyzed in both High- and Low-CO2 cells. In High-CO2 cells, the 18O2-ruptake in the light (UL) decreased by 65% upon addition of 3 mᴍ NaHCO3 , while 16O2-evolution (E) was increased approx. 1.8 times by the same treatment. 18O2-uptake in the dark (UD) was not affected by the addition of external inorganic carbon (Ci). The addition of 3.3 mᴍ NaHCO3 also affected UL and E in Low CO2-cells, however, to a minor extent. UL under CO2-saturating conditions was light intensity-independent up to 2 klux and 1.2 klux in High- and Low-CO2 cells, respectively.

Above these light intensities UL increased approx. 4-fold in High- and approx. 6-fold in Low-CO2 cells. Under CO2-limiting conditions, however, UL increased in High-CO2 cells even under very low light intensities, showing that photorespiratory oxygen uptake occurred even in the near vicinity of the light compensation point. Under C02-saturating and strong light conditions UL represented almost half of E in Low-CO2 cells and about 30 % of E in High-CO2 cells. In Low-CO2 cells addition of ethoxyzolamide (EZA), an inhibitor of carbonic anhydrase, enhanced UL and suppressed E and NET under CO2-limiting conditions, whereas the compound had only a minor effect on High-CO2 cells.

DCMU (3 μᴍ) strongly inhibited E and UL under CO2-saturating conditions, with the remaining UL being smaller than UD . KCN (1 mᴍ) and SHAM (1.5 mᴍ) added to DCMU-treated Low-CO2 cells suppressed UL by approx. 50 % . The resulting value corresponded to half of UD . KCN also inhibited E under CO2-saturating conditions, with UL being strongly enhanced showing a maximal uptake at 0.4 mᴍ KCN . Under these conditions NET was nearly zero. The effect seems to be due to an inhibition of RubisCO and an enhancement of Mehler reactions. At 0.7 mᴍ KCN , DCMU entirely inhibited UL , but oxygen uptake appeared increased after turning the light off. This uptake corresponded to approx. 60 % of UD . Whereas KCN and SHAM inhibited approx. 70 % of UD , only 16% of UL was suppressed. These results suggest that the contribution of mitochondrial respiration to UL was negligeable, since UL seemed to be suppressed in the light under CO2-saturated conditions. Iodoacetamide, which is an inhibitor of the Calvin cycle and thereby diverts carbon into the respiratory pathway, inhibited E and NET under CO2-saturating conditions, but did not affect UL . This result also shows that UL is not due to mitochondrial respiration. A hydroxylamine derivative [20, 21] which changes the ratio of the RuBP carboxylation to oxygenation activity in tobacco leaves did not affect this ratio in Chlorella.
Transport of Polyamines in Sugar Beet Seedlings
Authors: Christ Marbeth , Harr Jost , Felix Hansruedi
Published: August 2018

The high levels of polyamines generally found in cotyledons of seedlings might be exported to hypocotyls and radicles. 14C-Labelled putrescine applied to a sugar beet seedling through a cotyledon was found in small amounts as putrescine in the hypocotyl or radicle within a few minutes. Significant amounts of the labelled putrescine, however, were metabolized rapidly to compounds which could not be extracted into the organic phase on dansylation.
The Effect of Bialaphos on Ammonium-Assimilation and Photosynthesis II. Effect on Photosynthesis and Photorespiration
Authors: Ziegler Christine , Wild Aloysius
Published: August 2018

The application of bialaphos (phosphinothricyl-alanyl-alanine) effects a quick photosynthesis inhibition under atmospheric conditions (400 ppm CO2, 21% O2). However, under conditions (1000 ppm CO2, 2% O2) under which photorespiration cannot occur there is no photosynthesis inhibition. In the previous investigation it could be shown that bialaphos splits in plants into phosphinothricin and alanine. The inhibition of glutamine synthetase through freed phosphinothricin results in an NH4
+-accumulation and a decrease in glutamine. With the addition of glutamine, photosynthesis inhibition by bialaphos can be reduced. An NH4
+-accumulation takes place under atmospheric conditions as well as under non-photorespiratory conditions; though in the latter case, in less amounts. After adding glutamine and other amino acids the NH4
+-accumulation increases especially. This indicates that NH4
+-accumulation cannot be the primary cause for photosynthesis inhibition by bialaphos. The investigations indicate that for the effectiveness of either bialaphos or phosphinothricin, a process in connexion with photorespiration plays a considerable role. The glyoxylate transamination in photorespiration could be inhibited, which results probably on a glyoxylate accumulation. Corresponding investigations showed inhibition of photosynthesis as well as a direct inhibition of RubP-carboxylase with glyoxylate.
Kompetitive Hem m ung der Catechol-O-Methyltransferase durch die Tetrahydroisochinolin- Alkaloide Salsolidin und 1-Carboxysalsolin
Authors: Sanft Konstanze , Thomas Helmut
Published: August 2018

The tetrahydroisoquinoline alkaloids salsolidine (1-methyl- 6,7-dimethoxy-1,2,3,4-tetrahydroisoquinoline) and 1- carboxysalsoline (1-carboxy-1-methyl-6-hydroxy-7-methoxy- 1,2,3,4-tetrahydroisoquinoline), which are themselves not substrates for the enzyme catechol-O-methyltransferase, are - contrary to a hitherto existing view - able to inhibit competitively the methylation of the catecholamine metabolite 3,4-dihydroxybenzoic acid by the enzyme enriched from rat liver. The inhibitor constants were determined to be Ki = 0.19 mM for salsolidine and Ki = 0.44 mM for 1-carboxysalsoline.
Inhibition of Photosystem II by Ioxynil in Wild Type and Resistant Mutant of Synechocystis 6714
Authors: Ajlani G. , Meyer I. , Astier C. , Vernotte C.
Published: August 2018

A Synechocystis 6714 mutant resistant to the phenol-type herbicide ioxynil was isolated and characterized. Ioxynil was shown to inhibit both the donor and the acceptor sides of photosystem II, but at different concentrations. The mutation found in the psbA gene (encoding the D, protein) at codon 266 (asparagine to threonine) [G. Ajlani, I. Meyer, C. Vernotte, and C. Astier, FEBS Lett. 246, 207-210 (1989)] gives a ten-fold resistance of the acceptor side to ioxynil without any modification of the sensitivity of the donor side. Electron transfer between the primary and the secondary acceptor of photosystem II was identical in the mutant and the wild type. The mutant remains sensitive to atrazine and is even more sensitive to DCMU than the wild type.
Species and Genus Specificity of the Intergenic Spacer (IGS) in the Ribosomal RNA Genes of Cucurbitaceae
Authors: Torres R. A. , Zentgraf U. , Hemleben V.
Published: August 2018

The use of intergenic spacer (IGS) fragments of plant ribosomal DNA (rDNA) for the differ­ entiation between genera and species is tested by cross-hybridization experiments with different IGS probes of two Cucurbitaceae, Cucurbita pepo (zucchini) and Cucumis sativus (cucum ber). Hybridization with cloned fragments of different parts of the IGS of ribosomal DNA exhibit a different degree of conservation within and between the Cucurbitaceae genera. In general, Cucur­ bita species seem to be closer related to each other than the Cucumis species. A repetitive element of the external transcribed spacer (ETS) shows a more genus-specific pattern, reacting only with the respective genera; the region preceding the ETS is conserved between the Cucurbita species but also cross-hybridizes weakly with the Cucumis species. AGC-rich element of the Cucumis sativus IGS (“Cfo-cluster”) is present in small amounts in Cucumis melo (melon) and even less represented in other genera of the Cucurbitaceae.
Analogical Representation of the Genetic Code in Terms of the Virtual Base "e" and Codons of Triplets
Authors: Tohá J. C. , Soto M. A.
Published: August 2018

The analogical representation of the genetic code on base “e ” is described. The possible use of the “e ” base in codification processes is em phasized.
Molecular Orbital Analysis and Quantitative Structure-Activity Relationships for the Anthracycline Antibiotics
Authors: Bushelev S. N. , Stepanov N. F.
Published: August 2018

Semiempirical CNDO/2 calculations of the electronic and molecular structures have been car­ried out for six antitumor anthracycline antibiotics. The strong correlation between their biological activity and such molecular properties as chromophore dipole moment, energy of frontier orbitals, and steric volum es was found and the proper QSAR equations were constructed. The molecular mechanics model showed the weak dependence the DNA-intercalation energy on differences in chromophore constituents (C4 and C9 positions). The expression for the intercala­tion energy has also been obtained on the ground of a quantum-statistical approach: it was applied to the DNA -intercalation energy calculations for the same six anthracyclines. The results agree with the molecular mechanics ones quite satisfactory.
Inhibition of Hill Reaction by 2-Azido-s-triazine Derivatives: QSAR Study with Molecular Connectivity Indices
Authors: Šoškić Milan Š , Sabljić Aleksandar
Published: August 2018

2-A zido-s-T riazines, Connectivity Indices. Inhibition of Hill Reaction. Photosystem II, OSAR Modelling This study was undertaken to find a simple and accurate structural parameters for the quantita­tive description of inhibitory potency of 2-azido-s-triazines in Hill reaction and to gain more information about the mechanism of inhibition on molecular level. A very good correlation (r = 0.946) was obtained between the pl50 values (the negative logarithm of the molar concentra­tion that causes 50% inhibition) and the valence zero-order and the difference between the second-order and the valence second-order molecular connectivity indices. This model, when com pared with the empirical models based on the 1-octano/water partition coefficients and the chromatographic retention data, shows superior performance in accuracy and range of applicabili­ty. In addition, the direct correspondence between molecular structure and above connectivity indices makes it possible to locate structural features responsible for the inhibitory potency of 2-azido-s-triazines in Hill reaction. From our OSAR analysis, the interaction between the chloro­plast receptor site and 2-azido-s-triazines, which causes inhibition of Hill reaction, is primarily influenced by the size of alkylamino substituents and it accounts for the most variation in the pl50 data. The structural features of secondary importance that control the magnitude of pl50’s are the polarity of alkylamino chains and the degree of branching on alpha carbon atom of R:alkylamino substituent. Com pared with the main factor, the size of alkylamino substituents, they can be viewed as a fine tuning elements for the inhibitory potency of 2-azido-s-triazines.
Residual Motion of Hemoglobin-Bound Spin Labels as a Probe for Protein Dynamics
Authors: Steinhoff Heinz-Jürgen , Lieutenant Klaus , Schhtter Jürgen
Published: August 2018

The residual motion of spin labels bound to cysteine β93 of methemoglobin and oxyhemoglobin has been analyzed as a function of temperature and hydration. The rotational diffusion of the whole protein molecule has been prevented or restricted by crystallization, lyophilization or by high viscosity of the solution. The residual motion of the labels is characterized by an angle of the limited motion cone and their rotational correlation time using computer simulations of the E PR spectra. Two types of motion can be separated due to different correlation times and different dependenceson temperature and hydration. One of these motional mechanisms can be shown to be determined by protein fluctuations. Correlation times of these fluctuations decrease from 2 × 10-8 at T = 220 K to 10-9 s at T = 300 K in the samples of high water concentration. Strong correlation between the properties of the hydration shell and these fluctuations are observed.
On the Probability of a Common Origin for tRNA and 5S rRNA1
Authors: Staves Mark P. , Lacey Jr. James C.
Published: August 2018

As part of a continuing study on the origin of genetic coding and the process of protein synthesis, we have compared sequences of a large number of transfer RNAs and several 5S ribosomal RNAs using automated routines. Transfer RNAs were found to exhibit a high degree of matching with 5S rRNA s. These matches are considered to be indicative of sequence homology, reflecting common ancestry of the two molecules. Other possible explanations for the matches (convergence, transfection) are discussed and found to be highly implausible. Matches are also found between 5S rRNA and the introns of yeast precursor tRNAs. Many matches extend from before the 3′ end to after the 5′ end of circularized 5S rRNA sequences. Data is presented which indicates a tandemly duplicated or circular molecule could have served as the precursor to both 5S rRNA and tRNA . A derivative of this molecule may have functioned as a universal translator before the evolution of the highly specialized tRNAs.
Conformational Study of Some Amino Acid Conjugates of Indol-3-yl-acetic Acid (IAA) by 1H-NOE-Difference Spectroscopy. Structure/Auxin Activity Relationships
Authors: Duddeck Helmut , Hiegemann Monika , Simeonov Mario F. , Kojic-Prodic Biserka , Nigovic Biljana , Magnus Volker
Published: August 2018

Amino Acid Conjugates The conform ation of the side chain of indol-3-yl-acetic acid conjugates with am ino acids (L-alanine, glycine, L-i-leucine, L-a-aminobutyric acid, DL-aspartic acid, DL-phenylalanine, and 6-am inovaleric acid) has been studied by 1H -NMR -NOE -difference spectroscopy. Com parison with the conform ation in the solid state is given in the light of structure-activity relationships.
Accumulation Patterns of Polyamines and Hydroxycinnamic Acid Conjugates during Microsporogenesis of Corylus avellana
Authors: Meurer-Grimes Barbara , Strack Dieter , Wray Victor , Wierm Rolf
Published: August 2018

The am ounts of free, conjugated (hydroxycinnamic acid amides) and insoluble (poly)amines (putrescine, spermidine, spermine) as well as hydroxycinnamic acid esters (quinic acid esters) were determined during development of male inflorescences of Corylus avellana L. The location of these compounds either in sporophytic or gametophytic tissues and the possible correlation of their accumulation with exine formation are discussed.
The Effects of Wounding and Mite Infestation on Soybean Leaf Lipoxygenase Levels
Authors: Hildebrand David F. , Rodriguez Juan G. , Legg Cindy S. , Brown Grayson C. , Bookjans Gerhard
Published: August 2018

Numerous studies have demonstrated induction of proteins in plant tissues by wounding and infestations by various pests and pathogens. Lipoxygenase (LOX) is among the proteins that has been found to be induced by pathogens, but detailed information on the induction of LOX has not been reported. We have found a large (up to 10-fold) increase in LOX activity upon wounding of soybean (Glycine max L. Merr.) leaves and variable increases due to feeding of the twospotted spider mite. This induction in LOX activity was reflected in increases in amounts of both LOX protein and transcripts suggesting that the induction was at the transcriptional level. LOX activity was also found to be increased in unwounded leaves from plants with wounded leaves lower on the stem indicating that translocatable factors can cause remote induction of LOX activity.
Wechselwirkungen der DNA-Topoisomerase-Hemmstoffe Novobiocin und Nalidixinsäure mit einigen zytotoxischen Agentien. In-vitro-Untersuchungen an Thymus- und Milzzellen der Ratte
Authors: Tempel Karlheinz
Published: August 2018

Interactions of novobiocin (NB) and/or nalidixic acid (NA) with some cytotoxic agents - UV light (UV), X-rays, methylmethanesulfonate (MMS), bleomycin (BM), adriamycin (AM), cis-di-aminedichloroplatinum (II) (CDDP), mitomycin C (M IT), ethidiumbromide (EB), and suramin (SA) - have been investigated in thymic (T) and splenic (S) cells of the rat in vitro by measuring semiconservative (SDS) and unscheduled (UDS) DNA synthesis as well as sedimentation and viscosity of nucleoids. - Combining NB (900μg/ml) and/or NA (1800-3600 [μg/ml) with UV, MMS, BM, AM, M IT, and SA resulted in additive effects on SDS and UDS. Synergistic actions were observed in T- and S-cells simultaneously treated by NB and CDDP, whereas the effects of NB could be antagonized to some extent by EB and vice versa. In X-irradiated (≥ 28 Gy) cells pretreated by NB (NA), UDS was diminished (T-cells) or enhanced (S-cells). - The results are consistent with the following postulates: 1° in S-cells, DNA is much more supercoiled than in T-cells but in the opposite sense (positive superhelicity). 2° DNA supercoiling (DNA compactness) is influenced therefore by DNA-topoisom erase inhibitors and intercalating agents in a highly agent- and cell-specific manner.
Composition of Lipids of Piqui (Caryocar coriaceum Wittm.) Seed and Pulp Oil
Authors: Dresen Heidrun , Prasad R. B. N. , Gülz Paul-Gerhard
Published: August 2018

The lipid composition of Piqui (Caryocar coriaceum) seed oil and pulp oil was analyzed and found to contain triacylglycerols (95.1/95.3%) as major components followed by free fatty acids (1.7/1.6%), diacylglycerols (1.6/1.5%), squalene (0.3/0.3%) and monoacylglycerols (0.1/0.1%). Phospholipids were found only in seed oil (0.2%). They were identified as phosphatidylethanolamine and phosphatidylinositol. The sterol fraction (0.1/0.1%) contained stigmasterol and β-sito-sterol. In seed oil triacylglycerols the C-53 molecular species were dominated (52.8%) follow ed by C-55 (37.7%), C-57 (6.9%) and C-51 (2.6%) in minor quantities. In pulp oil triacylglycerols C-55 (51.7%) was predominant followed by C-53 (30.6%) and C-57 (17.7%). Palmitic (16:0) and oleic (18:1) acids were always the major fatty acids in both oils. In seed oil their quantities were nearly the same, whereas in pulp oil oleic acid was predominant. Composition of Lipids of Piqui (Caryocar coriaceum Wittm.)
The Lipoprotein and Peptidoglycan of Rhodobacter sphaeroides
Authors: Woitzik Daniela , Dierstein Roland , Weckesser Jürgen
Published: August 2018

The lipoprotein-peptidoglycan complex (rigid layer) from Rhodobacter sphaeroides was isolated. Treatment of the complex with N.O-diacetyl-muramidase cleaved off from the rigid layer the lipoprotein moiety with covalently bound peptidoglycan-fragments. The lipoprotein with the bound fragments showed a broad single band (Mr about 19,000) on SDS-polyacrylamide gels and had an isoelectric point of about 5.6. There was no serological cross-reaction with the rigid layer of Escherichia coli K12. The lipid moiety of lipoprotein with residual amino acids (mainly Gly, Ser, Gly, Asp) was obtained by Pronase E treatment of the rigid layer and chloroform -methanol extraction. It was free from phosphate and contained amide- and esterbound 18:1 and esterbound 16:0 and 18:0.

The isolated peptidoglycan, after enzymatical cleavage from the lipoprotein, had a chemical composition indicating Aly-type structure. Comparable studies, performed with Rhodobacter capsulatus 37b4 resulted in essentially similar results for rigid layer, lipoprotein and peptidoglycan compositions.
Effects of Simultaneous Supply of Silicon and Boron on Plant Growth and on Herbicide Toxicity
Authors: Bengsch E. , Polster J. , Schwenk M.
Published: August 2018

An optimal supply of biodisposable silicon and boron shows a synergistic stimulation effect on plant growth. Under these optimal growth conditions herbicides may become particularly toxic for cultural plants. Plants inhibited by herbicides show distinctly higher boron contents than that of untreated samples.
Application of Molecular Modelling Techniques to Pheromones of the Marine Brown Algae Cutleria multifida and Ectocarpus siliculosus (Phaeophyceae). Metalloproteins as Chemoreceptors?
Authors: Boland Wilhelm , Hoever Franz-Peter , Krüger Bernd-Wieland
Published: August 2018

The conformation of the two algal pheromones ectocarpene (1) and multifidene (2) was studied by the active analogue approach using molecular mechanics calculations within the software package SYBYL. A common conformation for both pheromones and all active analogues was filtered out by superposition- and energy minimizing procedures starting from crystallographic data of the Cambridge Structural Data Base (CSD). The interaction of the algal receptor systems with their olefinic pheromones and heteroanalogues is in excellent agreement with the assumption of a receptor-bound metal cation acting as the binding side.
Heuristic Approaches to Finding New Herbicides Active in the Chloroplast
Authors: Yoshida Shigeo
Published: August 2018

Herbicides inhibiting the photosynthetic electron transport (PET) system may be an important research target to introduce a biorational approach, since accumulated knowledge of the biological system has already reached a satisfactory level for detail explanation of their behaviors.

Besides structural modification of the known herbicides, an effective molecular design of potent PET inhibitors can be arrived at through consideration of the function of PQ at D 1 protein. New PET-inhibitory structures may also be discovered in natural products. Those compounds should be modified for the installation of herbicidal potency, which might require chemical parameters additional to those of the optimized structures at the binding site.

Binding studies of the PET inhibitors are essential in this type of research since it is very difficult to understand their structure-activity correlation in cases when a minor structural modification causes a dramatic change in their attacking sites.

It is also necessary to devise quick and reliable assay methods for herbicide screening in order to get accurate information about the structural effects and with this strategy the bio-assay using cultured cells has been proven to be a useful tool of structure-activity studies to detect the herbicidal requisites in the structures of PET inhibitors.
Studies on Herbicide Binding in Photosystem II Membrane Fragments from Spinach
Authors: Fromme R. , Technische G. Renger
Published: August 2018

The mechanism of atrazine binding and its modification by Chelex-100-induced Ca2+ depletion and proteolytic degradation by trypsin, was analyzed in PS II membrane fragments from spinach. It was found:

1) Chelex-100 treatment leads in a comparatively slow process (t1/2 = 5 - 10 min) to Ca2+ re­ moval from a site that is characterized by a high affinity as reflected by KD values of the order of 10-7
M. The number of these binding sites was found to be almost one per PS II in samples washed twice with Ca2+ -free buffer.

2) Chelex-100 treatment does not affect the affinity of atrazine binding but increases the susceptibility to proteolytic attack by trypsin.

3) The electron transport activity is only slightly affected by Chelex-100 treatment.

4) The atrazine binding exhibits a rather small T-dependence within the physiological range of 7 °C to 27 °C.

The implications of these findings for herbicide binding are discussed.
Interactions of the Bleaching Herbicide Clomazone with Reduced Glutathione and Other Thiols
Authors: Vencill William K. , Hatzios Kriton K. , Wilson Henry P.
Published: August 2018

The reactivity of the bleaching herbicide clomazone with reduced glutathione (GSH) was studied under in vitro conditions. Clomazone at 1.3 mM and GSH at 100 mM were reacted in a phosphate buffer (pH 8.8) at 25 °C for 3 days. The resulting synthetic product was identified as a GS-conjugate of clomazone by means of TLC, HPLC, and mass spectrometry (chemical ionization) procedures. Exogenous application of 0.5 mM of GSH and cysteine reduced significantly the bleaching effect of clomazone on leaf disks of velvetleaf (Abutilon theophrasti Medik.). Mercaptoethanol was not effective in antagonizing the bleaching effect of clomazone on velvetleaf leaf disks. These results show that clomazone can react with selected thiol compounds under in vitro conditions. The conjugation of clomazone with GSH may be involved in the metabolic detoxication of this herbicide in plants.
Glyphosate Transport and Early Effects on Shikimate Metabolism and Its Compartmentation in Sink Leaves of Tomato and Spinach Plants
Authors: Schulz Arno , Münder Thomas , Holländer-Czytko Heike , Amrhein Nikolaus
Published: August 2018

Glyphosate (N[phosphonomethyl]glycine) applied to an assimilate-exporting leaf of tomato or spinach plants is translocated via the phloem to the young growing areas of the shoot apex and root where it causes the rapid accumulation of shikimate and shikimate 3-phosphate to up to 16% of the dry weight or these tissues. Using the technique of non-aqueous fractionation of spinach leaves it was shown that the herbicidal target of glyphosate, the shikimate pathway enzyme 5-enolpyruvlyshikimate 3-phosphate synthase, is located within the chloroplast and that, in the presence of glyphosate. shikimate 3-phosphate accumulates in the same organelle, while shikimate was preferentially localized in the vacuolc. The major part of [l4C]glyphosatc imported into the leaf via the phloem was detected in the cytosolic fraction of the mesophyll cells.
Effect of Phosphinothricin (Glufosinate) on Photosynthesis and Photorespiration
Authors: Wendler Ch. , Wild A.
Published: August 2018

Phosphinothricin (PPT) causes a rapid inhibition of photosynthesis under atmospheric conditions (400 ppm CO2, 21% O2). However, under conditions (1000 ppm CO2, 2% O2) under which photorespiration cannot occur, there is no or only a very low rate of photosynthesis inhibition by phosphinothricin. Under both conditions, a strong NH4
+-accumulation is apparent caused through the inhibition of glutamine synthetase by phosphinothricin. This indicates, that NH4
+-accumulation cannot be the primary cause for photosynthesis inhibition by phosphinothricin, but a process in connexion with photorespiration plays a central role. Through the lack of amino donors, the transamination of glyoxylate to glycine in photorespiration cannot take place. PPT causes a great decrease in glutamine, glutamate, aspartate, serine, and glycine. Following addition of these amino acids to PPT, there is a decrease in photosynthesis inhibition by PPT. With the addition of glutamine or glutamate to PPT no decrease in serine and glycine is detected, because the transamination of glyoxylate to glycine in photorespiration can occur.
Diphenyl Ether Herbicides, a Tool to Elucidate the Mechanism of Photophosphorylation
Authors: Huchzermeyer Bernhard , Löhr Andreas
Published: August 2018

At least two different classes of ADP binding sites on chloroplast coupling factor are described in the literature. High-affinity sites are assumed to entail regulatory functions while low-affinity sites are involved in catalysis.

Diphenyl ether herbicides, acting as energy transfer inhibitors, interfere with nucleotide exchange on both categories of ADP binding sites. Their inhibitory potency varies depending on their substitution. We found that each diphenyl ether assayed revealed identical I50 values for inhibition of nucleotide interaction with both classes of binding sites.

We show here that diphenyl ether inhibition of energytransfer is primary based upon the interference with ADP binding to high-affinity binding sites. Thereby the control of proton permeability through the coupling factor complex is affected. Moreover, we found that the three β-subunits are not absolutely fixed in one conformational state: After covalently blocking the high-affinity site by an azido-label. a new high affinity state appeared on another β-subunit.
Epicuticular Waxes from Leaves of Maple (Acer pseudoplatanus L.)
Authors: Prasad R. B. N. , Gülz Paul-Gerhard
Published: August 2018

The epicuticular waxes from the leaves of maples (Acer pseudoplatanus L.) contained hydrocarbons (6.9%), wax esters (5.5%), aldehydes (38.1%), primary alcohols (10.2%) and fatty acids (17.1%). In addition to these common wax lipids, benzyl acyl esters (2.1%) and triterpenoids were also present. β-Sitosterol, β-amyrin and 24-methylene-cycloartenol were found in the form of acetates (14.4%). β-Amyrin was also present as free alcohol (4.9%) and esterified with long chain fatty acids (~ 0.7%).
Ascorbic Acid and Chlorophyll Content in Cell Cultures of Spruce ( Picea abies): Changes by Cell Culture Conditions and Air Pollutants
Authors: Messner Burkhard , Berndt Jürgen
Published: August 2018

Conifers contain ascorbic acid which is probably a protective against oxidative attacks. In yellow needles of damaged conifers the ascorbic acid content is increased, this suggests an induction by air pollutants and/or photooxidants of a protection mechanism in trees. To study this mechanism in more detail, a green cell suspension culture of spruce (Picea abies) has been established. These cells contain chlorophyll and have a photosynthetic capacity, but they need carbohydrates (sucrose) for growth and are thus photoheterotrophic. Their ascorbic acid content and its regulation depends on carbohydrates, the cells resemble healthy green needles in this respect; they appear to be qualified for studies on the induction of a defense mechanism. Treatment of these cells with SO2 (20 ppm, 4 days) ozone (1 ppm, 14 days) and vaporous H2O2 revealed a decrease of the ascorbic acid content and (to a lesser extent) also of chlorophyll. It is concluded that (photo-)oxidants obviously do not play such a dominant role in bleaching of needles as it is assumed. The increased ascorbic acid content found in needles of damaged conifers is probably not an induced protection mechanism against oxidants.
Superoxide Scavenging Properties of Flavonoids in a Non-Enzymic System
Authors: Huguet Ana I. , Máñez Salvador , Alcaraz María José
Published: August 2018

The superoxide anion scavenging activity of 38 flavonoids, some of them isolated from Side-ritis mugronensis, Sideritis javalambrensis and Cayaponia tayuya were investigated by measurement of their inhibition of nitroblue tetrazolium reduction. Isoorientin, orientin, amentoflavone, leucocyanidol, eriodictyol, datiscetin and robinetin behaved as potent scavengers and structure-activity relationships were established.
The SO4
·̄induced Oxidation of 2′-Deoxyuridine-5′-phosphate, Uridine-5′-phosphate and Thymidine-5′-phosphate. An ESR Study in Aqueous Solution
Authors: Hildenbrand Knut
Published: August 2018

Reactions of photolytically generated SO4
·̄ with 2′-deoxyuridine-5′-phosphate (5′-dUMP), uridine-5′-phosphate (5′-UMP) and thymidine-5′-phosphate (5′-dTMP) were studied by ESR spectroscopy in aqueous solution under anoxic conditions. From 5′-dUMP and 5′-UMP the 5′,5-cyclicphosphate-6-yl radicals 10 and 11 were generated (pH 2 -11) whereas from 5′-dTMP at pH 3 -8 the 5,6-dihydro-6-hydroxy-5-yl radical 14 and at pH 7 -1 1 the 5-methylene-2′-deoxyuridine-5′-phosphate radical 15 was produced. In the experiments with 5′-UMP in addition to radical 11 the signals of sugar radicals 12 and 13 were detected. It is assumed that the base radical cations act as intermediates in the SO4
·̄-induced radical reac­tions. The 5′-phosphate group adds intramolecularly to the C(5)−C(6) bond of the uraclilyl radical cation whereas the thymidyl radical cation of 5′-dTMP reacts with H2O at pH < 8 to yield the 6-OH-5yl adduct 14 deprotonates at pH > 7 thus forming the allyl-type radical 15. In 5′-UMP transfer of the radical site from the base to the sugar moiety competes with intramolecular phosphate addition.