bluuebunny/crossref_metadata_2025_split huggingface dataset:
Isomerization of Peroxidizing Thiadiazolidine Herbicides Is Catalyzed by Glutathione S-Transferase
Authors: Nicolaus Beate , Sato Yukiharu , Wakabayashi Ko , Böger Peter 
Published: August 2018

Abstract
Thiadiazolidine-converting activity (isomerase), detected in a 45-75% ammonium sulfate precipitate from corn seedlings extracts, was purified by chromatography on hydroxyapatite and by anion exchange on Mono Q Sepharose. Two fractions 1 and 2 with isomerase activity were separated on Mono Q by combination of a stepwise elution and continuous salt gradient; fraction 2 eluting at higher salt concentrations was found the most active. Total activity could be enhanced by treatment of seedlings with naphthalic anhydride. Both fractions containing isomerase activity were further purified by glutathione-(GSH) agarose affinity chromatography and characterized by their specificity for different thiadiazolidines. Sodium dodecyl sulfate polyacrylamide gel electrophoresis and gel filtration revealed that the isomerase of fraction 2 consists either of a homodimer or a heterodimer of two proteins with apparent molecular weights of 28 and 31 kDa, respectively. The protein pattern as well as the strict dependence of activity on thiol groups (GSH or dithiothreitol) suggested a glutathione Stransferase (GST) catalyzing the thiadiazolidine conversion. Further evidence was obtained by measuring reactions specific for GSTs in both purified fractions, namely the conjugating activity for l-chloro-2,4-dinitrobenzene (CDNB ). atrazine and metazachlor. While no atrazine turnover was found, metazachlor and CDNB conjugation occurred rapidly. Both fractions differed in their activities to several GST substrates with fraction 2 being more effective in metazachlor but less active in C DN B conjugation. Inhibitors specific for GST-catalyzed reactions also inhibited thiadiazolidine conversion confirming that isomerizing activity is attributed to a GST form. We conclude that GST isoforms with different affinities towards thiadiazolidines have been isolated. CDNB activity, molecular weight, the protein pattern on SDS-PAGE as well as the amino acid sequence of one of its polypeptides suggest that fraction 1, less active in thiadiazolidine isomerization, is identical to GST I. The second peptide of this fraction was resistant to Edman degradation probably due to N-terminal blockage. The properties of the high isomerase activity found in fraction 2 are in agreement with characteristics of a GST previously termed as isoform II.
Characterisation of a Neutral Protease Produced by Micrococcus luteus
Authors: Ilori M.O. , Amund O.O. , Omidiji O. 
Published: August 2018

Abstract
A proteolytic enzyme produced by a cassava-ferment­ing strain of Micrococcus luteus was extracted and puri­fied 50-fold by gel filtration and ion exchange chromatography.
The optimum pH for the enzyme was 7.0, the optimum temperature 25 °C, the apparent molecular weight 42 kDa and the Km value, 0.45 mg ml-1 with casein as substrate. The enzyme was stimulated by Ca2+ and Mg2+ but inhibited by Zn2+ and Co2+ ions. Other inhibitors were EDTA, KCN, citric acid and L-cysteine indicating the enzyme to be a metalloprotease.
Cell Surface Glycoconjugates of Euglena gracilis (Euglenozoa): Modifications under Potassium and Magnesium Deficiency
Authors: Preisfeld Angelika , Scholten-Beck Gabriele , Ruppel Hans Georg 
Published: August 2018

Abstract
Biochemical and ultrastructural examinations on the pellicle of autotrophically grown Eu­glena gracilis were carried out after three days under potassium and magnesium deficiency. Cell-surface changes were detected by lectin assay. Compared to cells grown in complete medium, deficient cells become larger in shape, accompanied by rising carbohydrate, chloro­phyll and protein content, bind more and other lectin molecules: an increase of mainly galactose and N-acetylgalactosamine receptors was observed. Investigations with the mucilage stains alcian blue and ruthenium red indicated that mucilaginous material is released under deficient conditions, whereas the control cells show a strong precipitate of these stains well inside the cells beneath the pellicle.
Cytotoxicity and Antitumor Activity of Platinum(II) Complexes of Aromatic and Cycloalkanecarboxylic Acid Hydrazides
Authors: Kushev Daniel N. , Spassovska Nadejda C. , Taxirov Svetoslav I. , Grancharov Konstantin C. 
Published: August 2018

Abstract
New platinum(II) complexes of cyclohexanecarboxylic acid hydrazide (chcah) were synthesized and characterized by elemental analysis, IR. and 1H NMR spectra. Their inhibitory effects on cell growth and macromolecular synthesis of Friend leukemia cells in culture as well as the in vivo antitumor activity towards L1210 leukemia in mice were compared with those of complexes containing differently substituted aromatic acid hydrazides. Some of the complexes exhibited antineoplastic activity. No correlation between the in vitro cytotoxicity and the in vivo antitumor activity was found. However, there was a relationship between the in vitro macromolecular synthesis inhibition profile and the in vivo antineoplastic effect, similar to that of cisplatin. On the other hand, only agents containing one ammine ligand were active in vivo. The substitution of the aromatic ring by a cycloalkane residue increased significantly the antitumor effect, with [Pt(NH3)(chcah)Cl2] being the most active compound in this study.
Folding of the SPKK Rich Peptide in the Presence of the Octa-Oligonucleotide
Authors: Zubrzycki Igor Z. , Bohm Lothar 
Published: August 2018

Abstract
The nucleosome contains of 200 base pairs of DNA complexed with four core histone complex: H2A , H2B, H3, and H4. The fifth histone species, the H1 histone, interacts with linker DNA connecting neighbouring nucleosomes. We have studied the influence of the phosphorylation on the interactions of a repeating unit 15 residues long, containing the SPKK motif, the motif thought to induce turn along peptides sequences, enclosed within the trout testis H1 C-terminal domain with octanucleotide by means of the thermal denaturation and CD technique. The results indicate that the peptide preferentially binds to a single stranded oligonucleotide. It has been shown further that there is no β structure present but a distorted helical structure has been detected.
Two Ways of Hydrogen Peroxide Formation in the Oxidative Inactivation of Cyanobacterial Glutamine Synthetase
Authors: Martin Gottfried , Böger Peter 
Published: August 2018

Abstract
Using crude extracts from the cyanobacterium Anabaena variabilis glutamine synthetase (GS) activity was rapidly irreversibly reduced to about 60% during dark incubation ("sponta­neous GS inactivation"). An additional decrease was observed by the addition of ammonia in the light ("ammonia-mediated inactivation"). Both effects were prevented by EDTA, MnCl2 or catalase indicative of the involvement of H202. This is a key intermediate in oxidative enzyme inactivation. In both spontaneous and am monia-mediated GS inactivation H202 is produced in different ways. Spontaneous inactivation is prevented by depletion of reduced pyridine nucleotides which apparently donate electrons to produce H202. Fractionation of the crude extract showed that the light-enhanced GS inactivation by ammonia required the presence of thylakoid membranes. The photosynthesis inhibitor DCMU decreased GS inactivation by ammonia. For the inactivation in the light apparently H202 is produced from super­ oxide during photosynthetic electron transport.
Antioxidant Activity of Flavones from Scutellaria baicalensis in Lecithin Liposomes
Authors: Gabrielska Janina , Oszmiańsk Jan , Żyłka Romuald , Komorowska Małgorzata 
Published: August 2018

Abstract
Trihydroxyflavones of Scutellaria baicalensis, Antioxidant Activity, Liposome, Peroxidation, MDA The antioxidant effect of a trihydroxyflavone extract from Scutellaria baicalensis on oxida­ tion induced by ultraviolet light, was studied with phosphatidylcholine liposome membrane. Also, as standards, the antioxidative activity of baicalin, wogonin, baicalein and butylated hydroxytoluene (BHT) was investigated. Comparison of the protective effects of thecom­pounds studied against photoinduced lipid peroxidation in lecithin liposome membranes showed that: (1) the inhibitory effect of those compounds (at 1.2 mol% antioxidant content in liposomes) on TBA reactive materials from lipid peroxidation decreased in the order of baicalin > BHT ≅ Scutellaria baicalensis. These were found much greater than wogonin and baicalein; (2) the depressed effect of those compounds (at 1.1 mol% compounds content in liposomes) on the production of conjugated dienes (proportional to oxidation index) could be classified as follows: Scutellaria baicalensis ≅ baicalin > BHT, these three were found more active much greather than baicalein and wogonin. Results obtained by ESR measure­ment confirm that Scutellaria baicalensis extract and the BHT compound significantly de­ pressed the effect of liposome oxidation. It was found that the new trihydroxyflavones of Scutellaria baicalensis, ensured a very satisfactory concentration-dependent protection of the liposome membrane against UV-induced oxidation. These findings suggest that some of the beneficial effects of the extract of the Scutellaria baicalensis can be mediated in certain diseases (for example in skin diseases) by their ability to scavenge free radicals and by their protective effect on lipid peroxidation caused by sunlight irradiation.
A 5,6-Dihydro-isopyoverdin from Azomonas macrocytogenes
Authors: Michalke R. , Taraz K. , Budzikiewicz H. , Thonart Ph. 
Published: August 2018

Abstract
From the culture medium of Azomonas macrocytogenes a 5,6-dihydro-isopyoverdin could be isolated which includes the same peptide chain as the accompanying isopyoverdins (azoverdins). As analogous pairs had been encountered in the pyoverdin series where a dihydro derivatives are considered to be the immediate precursors of the pyoverdins, the same biogenetic sequence can thus be assumed for the iso-series.
Independently Acting Oxygen-Forming Complexes of Photosystem II in Cyanobacteria A Study in the Filamentous Cyanobacterium Oscillatoria chalybea
Authors: Spiegel S. , Burda K. , Bader K. P. , Schmid G. H. 
Published: August 2018

Abstract
It has been postulated that the oxygen-evolving centers of photosystem II do not operate independently in the cyanobacterium Synechococcus leopoliensis in contrast to those of the chlorophyte Chlorella vulgaris and the diatom Phaeodactylum tricornutum (Mauzerall and Dubinsky (1993), Biochim. Biophys. Acta 1183, 123-129). Dependence would mean the existence of charge transfer among adjacent units and would be manifested by different saturation curves for the individual flashes of a sequence (different cross-sections), stronger damped oscillations and oxygen formation under the first flash, independently of the length of dark adaptation. We show in the present publication that in the filamentous cyanobacterium Oscillatoria chalybea the O2-evolution pattern which shows an O2-signal under the first flash (despite dark adaptation) can be explained within the heterogeneous Kok-model, assuming a non-standard initial S-state distribution (Bader, Thibault and Schmid (1983), Z. Naturforsch. 38c. 778-792).
Notholaena Terpenoids: Two New Epimeric Diterpenes from the Frond Exudate of the Fern, Notholaena rigida
Authors: Arriaga-Giner Fco. Javier , Rumbero Angel , Wollenweber Eckhard 
Published: August 2018

Abstract
From the farinose frond exudate of the fern Notholaena rigida two new triterpenes have been identified. They were found to be the C-24 epimers of 12 β-acetoxy-24, 25-diO-isopropylidene-dammarane-3 β, 20(S),24,25-tetra-ol. A survey of all triterpenes found in Notholaena is presented.
Exudate Flavonoids in Asteraceae from Arizona, California and Mexico
Authors: Wollenweber Eckhard , Dörr Marion , Fritz Hannelore , Papendieck Sabine , Yatskievych G. , Roitman James N. 
Published: August 2018

Abstract
A series of Asteraceae, belonging to the tribes Astereae, Eupatorieae, Helenieae and Heli­antheae, have been analyzed for the presence of flavonoid aglycones accumulated on leaf and stem surfaces. Methyl ethers of apigenin, luteolin, kaempferol, and quercetin as well as methyl ethers of their relevant 6 -hydroxy derivatives were abundant, whereas 8 -O-substi-tuted derivatives and flavanones were encountered only occasionally; 6 ,8 -di-O-substituted flavonols were found in only one species.
Production of Calcium Oxalate Crystals by Two Species of Cyathus in Culture and Infested Plant Debris
Authors: Tewari Jalpa P. , Shinners Tracy C. , Briggs Keith G. 
Published: August 2018

Abstract
Hyphae of Cyathus striatus and C. olla in culture and on infested plant debris were heavily encrusted with crystals. Scanning electron microscopy revealed that raphide-and styloid­ shaped crystals were associated with the hyphae of C. olla in canola stubble and in culture. Bipyramidal crystals were also present in culture. Distinct raphide druses developed on C. striatus hyphae colonizing wood chips, but in culture most crystals were bipyramidal or other shapes. Energy-dispersive X-ray microanalyses, FT/IR spectroscopy, and 13C NMR spectros­ copy determined that these crystals were calcium oxalate. This is the first report of calcium oxalate crystal production by these fungi. This characteristic has implications towards decomposition of organic matter, biomineralization, nutrient cycling, and soil genesis.
New Gadolinium Complexes as Magnetic Resonance Imaging - Contrast Agents
Authors: Wagner Manuela , Ruloff Robert , Hoyer Eberhard , Gründer Wilfried 
Published: August 2018

Abstract
We have investigated the physicochemical and paramagnetic properties of the new gado­linium complexes of N-(pyrid-2-yl-methyl)-ethylenediam ine-N,N',N'-triacetic acid (Gd-PED TA) and N -tris(2-aminoethyl)amine-N',N',N",N",N''',N'''-hexaacetic acid (Gd-TTAHA). The relaxivities as well as the thermodynamic and conditional stability constants of these complexes with respect to the physiological relevance were determined and discussed in comparison with the commercially available gadolinium(III) diethylenetriaminpentaacetic acid/ gadopentate dimeglumine (G d-DTPA, Magnevist®). In case of Gd-TTAHA a twofold higher relaxivity and a complex stability similar to Gd-DTPA were determined. It is shown, that lower concentrations of Gd-TTAHA are sufficient for the same signal enhancement in the T1-weighted MR image compared with Gd-DTPA and, thus, the use of the new contrast agent Gd-TTAHA should diminish risks for health. Therefore, Gd-TTAHA might be used potentially as a new contrast agent for clinical MRI application.
In Vitro Effects of Colchicine on Human Erythrocyte Membranes: An ESR Study
Authors: Korkmaz Özden , Korkmaz Mustafa , Aksöz Erol 
Published: August 2018

Abstract
Colchicine (CC) is an antimitotic and antitubular agent which is currently used in medicine as a drug to treat various diseases. In spite of its widespread use the interaction of this drug with membranes is not yet known clearly. To characterize alterations in membrane molecular dynamics produced by CC, human erythrocytes were spin-labeled with 5-doxylstearic acid (5-DSA) and 16-doxylstearic acid (16-DSA), and membrane fluidity was quantified by meas­uring the changes in the order parameter (S) which reflects the anisotropy due to restricted motional averaging, correlation time (τc) representing the spin label tumbling rate in the sample and phase transitions derived from ESR measurements. CC induced significant changes in both order parameter and correlation time at the surface of 5-DSA labeled membrane, but this was not the case at the core of 16-DSA labeled membrane. Order parameter, S and rotational correlation time, τc, showed a biphasic character in the temperature range of 5−50 °C. This fact was used to calculate phase transition temperatures and activation energies of untreated (control) and treated erythrocyte cells with CC.
Feral Honey Bees in the Sonoran Desert: Propolis Sources other than Poplars (Populus spp.)
Authors: Wollenweber Eckhard , Buchmann Stephen L. 
Published: August 2018

Abstract
In Central Europe and other temperate regions the lipophilic bee hive product propolis normally originates from the bud exudate of poplar trees that is collected by the bees. Based on bee observations, various other sources have been discussed in particular for tropical regions, but in only few cases the origin has been proved by analytical methods. We have analyzed propolis samples from managed honey-bees as well as from feral bee colonies in the Sonoran Desert. Propolis collected in hives out of flight reach of poplars contained flavonoid aglycones and other phenolics that point to specific plants as the source of propolis in this area, namely Ambrosia deltoidea and Encelia farinosa.
Reaction of Hypochlorous Acid with Bovine Nasal Cartilage Comparison to Pig Articular Cartilage
Authors: Schiller Jürgen , Arnhold Jürgen , Zachäus Annett , Klaus Arnold 
Published: August 2018

The action of sodium hypochlorite (NaOCl) on bovine nasal cartilage was studied by proton nuclear magnetic resonance (1H-NMR) spectroscopy in order to model degradation processes of cartilage caused by neutrophil-derived hypochlorous acid.
Nasal cartilage was chosen as a mean of comparison because it differs from articular cartilage in its composition. It contains some more proteoglycans, i.e. polymeric carbohydrates and less collagen than articular cartilage. This is important for studying the influence of hypochlorous acid on cartilage components (collagen and polysaccharides). Cartilage samples were incubated at 37 °C with phosphate buffer in the presence or absence of NaOCl. Supernatants were collected and assayed by NMR-spectroscopy. In the presence of pure phosphate buffer, the supernatants of bovine nasal cartilage were less rich in low molecular mass metabolites (e.g. amino acids, lactate) than articular cartilage. However, intense signals for highly mobile N acetyl groups of cartilage polysaccharides were detectable in nasal cartilage.
NaOCl caused an increase in signals for acetate and formiate. Signals for N-acetyl groups rose only during the first 25 minutes of incubation with NaOCl. Then, their concentration decreased markedly. These changes were related to an enhanced release of Chondroitinsulfate from nasal cartilage
Effect of MgCl2 and Phosphatidylglycerol on CaCl2-Mediated Recovery of Oxygen Evolution in a Photosystem II Complex Depleted of the 17 and 24 kDa Extrinsic Proteins
Authors: Nénonéné E. K. , Méthot M. , Fragata M. 
Published: August 2018

Abstract
Phosphatidylglycerol (PG) is an anionic lipid of the thylakoid membrane of higher plant chloroplasts. PG was shown previously to stimulate the evolution of oxygen in intact pho­tosystem II (PSII) membranes [Fragata, M., Strzałka, K. and Nénonéné, E. K. (1991) J. Photochem. Photobiol. B: Biol 11, 329-342], In this work, a study was undertaken of the effect of MgCl2 and PG on the CaCl2-mediated recovery of oxygen evolution in a PSII complex depleted of the extrinsic proteins (EP) of molecular masses 17 kDa (EP17) and 24 kDa (EP24), hereunder designated d17.24PSII. This molecular system is structurally close to the PSII core complex of cyanobacteria and is therefore useful in the comparative analysis of PSII-PG relationships in cyanobacteria and the higher plants. This work reveals a new aspect of the thylakoid lipids role in the PSII function, namely the PG effect on intact PSII is observed as well in d17.24PSII. The results show that phosphatidylglycerol has the ability to compensate for the loss of EP17 and EP24 in the PSII complex. That is, PG restores the oxygen evolution in d17.24PSII incubated in the presence of MgCl2 and/or CaCl2 to the levels observed in native PSII. Moreover, the site of H2O degradation in d17.24PSII, including most probably the pool of calcium and chloride ions, would seem to be protected by phosphatidyl­glycerol. This suggests that one of the docking sites of PG in the PSII complex is near EP24, inasmuch as this extrinsic protein participates in the regulation of the affinity of the calcium and chloride ions to the water oxidation site. Furthermore, taking into account that in d17.24PSII the PSII core complex is directly exposed to PG, then the phospholipid effect reported here indicates that phosphatidylglycerol might be a functional effector and mem­brane anchor of the D1 protein in the PSII core complex as was shown recently in the cyanobacterium Oscillatoria chalybea [Kruse, O. and Schmid, G. H. (1995) Z. Naturforsch. 50c, 380-390],
Peroxidase-Polyphenol Oxidase Association in Dioscorea esculenta
Authors: Okpuzor J. , Omidiji O. 
Published: August 2018

Abstract
A crude enzyme extract from Dioscorea esculenta var. fasiculata tissue subjected to ion exchange chromatography on DEAE-Sephadex A-50 column. This proced ure resolved the extract into two main protein peaks one of which eluted through the column relatively unbound while the other protein peak which remained bound to the column was eluted with 1.0 ᴍ NaCl. Both protein peaks contained polyphenol oxidase (PPO) and peroxidase (POD) activities. The non-binding protein peak was resolved by gel filtration on Sephadex G-200 into distinct PPO and POD activities and by virtue of their apparent molecular weights of 95.5 Kd and 38.0 Kd for PPO and POD respectively were determined to be the typical enzymes. The PPO activity was completely inhibited invitro by 5 mᴍ polyvinyl pyrrolidone (PVP). The binding protein peak was not resolved by gel filtration. It contained PPO activity which was not inhibited by PVP and a POD activity which was completely inhibited by dithiothreitol (DTT) This ionic protein peak contained 60% of total POD in the tissue, has an apparent molecular weight of 56 Kd and is suggested to be a strongly anionic peroxidase which also exhibits polyphenol oxidase activity.
ʟ-Phenylalanine Effect on Rat Diaphragm Acetylcholinesterase and Na+,K+-ATPase
Authors: Tsakiris Stylianos , Kouniniotou-Krontiri Panagiota , Schulpis Kleopatra H. 
Published: August 2018

Abstract
The effect of different L-phenylalanine (Phe) concentrations (0.24-12.1 mᴍ) , on acetylcho­linesterase (AChE) and Na+,K+-ATPase activities of diaphragm homogenates from 21-day old rats and pure enzymes, was investigated at 37 °C. AChE and N a+,K+-ATPase activities were determined after preincubation with Phe. AChE activity in diaphragm homogenate or in pure eel E. electricus enzyme showed a decrease, which reached a maximum of 18% with Phe concentrations of 0.9-12.1 mᴍ. However lower Phe concentrations (0.24 mᴍ) increased the enzyme activity (by approximately 22%), only in the diaphragm homogenate. Dia­phragm-associated Na+,K+-ATPase activity showed a progressive and concentration-depen­ dent decrease, by about 30-35% in the presence of high Phe concentrations. Pure enzyme activity (from porcine cerebral cortex) was not affected by high Phe concentrations (>0.48 m M) , while it was increased by low concentrations. The above results suggest; a) A direct inactivating effect of high Phe concentrations on AChE and an indirect activating effect induced by low concentrations, b) A direct activating effect of low Phe concentrations and an indirect inactivating effect of high ones on Na+,K+-ATPase. c) The combination of high Phe concentrations effects on AChE and Na+,K+-ATPase could influence the levels of the diaphragm synaptic ACh.