bluuebunny/crossref_metadata_2025_split huggingface dataset:
Plant NAD-Dependent Glutamate Dehydrogenase. Purification, Molecular Properties and Metal Ion Activation of the Enzymes from Lemna minor and Pisum sativum
Authors: Scheid Heinz-Walter , Ehmke Adelheid , Hartmann Thomas 
Published: August 2018

Abstract
Glutamate dehydrogenase (ʟ-glutamate: NAD+ oxidoreductase (deaminating) EC 1.4.1.2) has been purified to homogeneity from Lemna minor and seeds of Pisum sativum. As established by polyacrylamide gel electrophoresis the Pisum-enzyme constitutes a multiple pattern of seven char­ge isoenzymes whereas the Lemna enzyme shows one single protein band. Molecular weights of 230 000 were calculated for both enzymes by sedimentation equilibrium measurements (Pisum-enzyme) and comparative gel filtration (Lemna-enzyme). Sodium dodecyl sulfate gel electrophoresis and electron microscopic observations revealed that both enzymes are composed of four identical subunits (molecular weight 58 500) arranged in a tetraedric structure. The amino acid compositions of both enzymes are similar to those of various hexameric glutamate dehydrogenases. The N-terminal amino acid of the Pisum-enzyme is alanine. Both enzymes require Ca2+ for maximal catalytic activity. For the Lemna-enzyme the K0.5 values for Ca2+ are 22 µᴍ (NADH-dependent reaction) and 4 µᴍ (NAD+ -dependent reaction), respectively. Ca2+ which to some extent can be replaced by Zn2+ does not affect the enzyme aggregation but seems to govern a reversible equilibrium between catalytically active and inactive enzyme forms.
Flavonoids and Related Compounds in Leaves of Pinaceae, IV.
Authors: Genderen H. H. van , Schaik J. van 
Published: August 2018

Abstract
Several flavonoids were isolated from needles of Cedrus deodara. Among them were the 3-glucosides of kaempferol, isorhamnetin and syringetin. Apigenin-7-glucoside and presumably an alkylkaempferol-3-diglucoside were also present. Kaempferol-3-glucoside occurred both free and acylated with p-coumaric acid and/or ferulic acid.
The Regeneration of Virus-Free Plants from Cucumber Mosaic Virus- and Potato Virus Y-Infected Tobacco Explants Cultured in the Presence of Virazole
Authors: Cassells Alan C. , Long Roger D. 
Published: August 2018

Abstract
Adventitious shoots regenerated from tobacco explants taken from donor-plants infected with cucumber mosaic virus and potato virus Y, were virus infected. Similar ex-plants cultured in the presence of Virazole were virus-free.
Über die quantitative fluorometrische Bestimmung von DNA mit Ethidiumbromid in der Zelle und die Konstanz der Quantenausbeute des Ethidium-DNA-Komplexes im biologischen Milieu / On the Quantitative Fluorometric Determination of Cellular DNA by Ethidium Bromide and the Constancy of the Quantum Yield of the Ethidium -DNA -Complex in the Biological Environment
Authors: Pauluhn Jürgen , Naujok Annemarie , Zimmermann Herbert W. 
Published: August 2018

The fluorescent staining of fixed A9 cells (mouse fibroblasts) with ethidium bromide E has been investigated qualitatively and quantitatively. E is bound to DNA, RNA and protein. After enzymatic RNA digestion and staining at pH = 4.0 the dyestuff is bound to DNA specifically. The formed E-DNA-complex is stoichiometric if DNA will be saturated by high dye concentra­tion, CF= 1.0 × 10-2 ᴍ. The stoichiometric factor n = 0.21 was determined from Scatchard bind­ing isotherms and by spectrophotometric titration.
The binding of E to DNA and RNA has been investigated by binding isotherms. E is bound to DNA by intercalation and by ionic interaction. It is bound to RNA by ionic interaction only. The ionically bound dyestuff can be replaced by salts like LiCl from DNA and RNA. Only inter­calated E remains. The competitive salt effect can be used to avoid the enzymatic RNA digestion in the specific staining of DNA.
Within the cell the E-DNA-complex fluoresces strongly. Using a microspectrophotometer we determined the fluorescence intensity J and the extinction E in cell sections of q = 1 μ2 area. The fluorescence was excited in the minimum of the absorbance of the E-DNA-complex at λ1 = 365 nm. The extinction E2 was measured in the short wavelength band at λ2 = 260 nm. Under these conditions we received a linear relation J = J(E2) up to high extinctions E2. The quantum yield Q of the E-DNA-complex is nearly constant and independent of the biological environment. Q is also unaltered by LiCl. Within the limits of error intercalated and ionic bound dye have the same quantum yield. Under the conditions of stoichiometric staining the amount of E-DNA- complex and therefore DNA in the cell can be determined by J.
The extinction coefficient Ɛ2 = 45200 ᴍ-1 cm-1 of the E-DNA-complex at 260 nm was calcu­lated from the concentration dependence of the absorbance spectra using the law of mass action. By Ɛ2 the amount of DNA in the cell is accessible from J. According to our measurements with A9 cells the superficial density of DNA has the order of magnitude ρɴ= mɴ/q = 101 nmol cm-2, the amount mɴ of DNA per section q=1 μ2, mɴ = 10-1 fmol, and the DNA concentration in the cell nucleus Cɴ = 10_1 ᴍ. The ray pass and diagram of electronics of the used microspectrophotometer are described.
Oral Cleansing in Spiders is Gland Mediated!
Authors: Sittertz-Bhatkar Helga 
Published: August 2018

Abstract
Histochemical and micromorphological investigations of the gnathocoxal gland in spiders brought out its uniquely adaptive cleansing function. The prey particulates, caught in the oral mi­ crostructures, are bound with mucopolysaccharides or glyco-muco-proteins from the glandular secretions in Araneus and Theridion species into a bolus, and are expelled following each food up­ take.
Umbelliferone in Needles of Picea abies *
Authors: Esterbauer Hermann , Schwarzl Elisabeth , Grill Dieter 
Published: August 2018

Abstract
A compound showing blue fluorescence under UV-light was isolated from spruce needles and identified as umbelliferone. Structure analysis was based on UV and mass spectroscopy as well as chromatographic comparison with authentic material. Quantitative evaluation by direct measurement of the fluorescence of the umbelliferone spot separated by TLC revealed that the umbelliferone content shows great variation within different individual trees ranging from 0.42-42 (μg/g fresh weight. Only minute amounts are present as free umbelliferone while the abundant part is present as β-glucoside.
A Series of Novel Flavanones from Fern Exudates
Authors: Wollenweber Eckhard , Dietz Volker H. , Schillo Detlef , Schilling Gerhard 
Published: August 2018

Abstract
The white farinose exudate on the fronds of Cheilanthes argentea contains a series of flavanones as minor constituents. These were identified by spectroscopic methods as: 5,4′-diOH,6,7-diOMe flavanone and its 4′-OMe derivative, 5,4′-diOH,7,8-diOMe flavanone and its 4′-OMe derivative, 5,6-diOH,7,8,4′-triOMe flavanone, 5,4′-diOH, 6,7,8-triOMe flavanone and its 4′-OMe derivative. The farina of Notholaena limitanea var. mexicana contains eriodictyol-7,4′-di-methyl ether and eriodictyol-7,3′, 4′-trimethyl ether as minor components. Both compounds were also identified in the exudate of N. fendleri, together with naringenin-7-OMe and naringenin-4′-OMe. In N. lemmonii var. lemmonii trace amounts of 5-OH,7,3′,4′,5′-tetra-OMe flavanone were detected. Nine of these substances are novel natural flavanones.
Isolierung und Charakterisierung einer Acetylester-Hydrolase aus Aspergillus rtiger / Isolation and Characterization of an Acetylester-Hydrolase from Aspergillus niger
Authors: Schöbel B. , Pollmann W. 
Published: August 2018

Abstract
The characteristic features of an acetic acid esters hydrolyzing enzyme (acetylesterase, EC 3.1.1.16) are described. The pH- and temperature optimum were 7.0 and 40 °C respectively. The stability of the enzyme regarding different pH- and temperature conditions was investigated. The molecular weight of the acetylesterase could be determined to 160000. A small acetic ester hydrolyzing activity was found too with a molecular weight of about 25000. The activity was not inhibited by addition of di-isopropylphosphorofluoridate (DFP) or physostigmine. The KM-value for glyceryl triacetate was about 90 mM. Concentration of the enzyme was done by ultrafiltration and column-chromatography. The enzymatic activity tests were performed titrimetrically using glyceryl triacetate for substrate.
Effects of Vanadate on the Molybdoproteins Xanthine Oxidase and Nitrate Reductase: Kinetic Evidence for Multiple Site Interaction
Authors: Ramadoss Candadai S. 
Published: August 2018

Abstract
The inhibition of the activity of xanthine oxidase by vanadate was strikingly similar to vanadate inhibition of another molybdoprotein nitrate reductase. Although the main catalytic activity of both enzymes was inhibited, the partial NADH oxidase activity associated with these enzymes was stimulated several fold. It appears that the metal ion binds at multiple site in both enzymes. In the absence of any enzymes a combination of vanadium (V) and molybdenum (V) in air was found to oxide NADH rapidly.
Untersuchungen über Pherom one bei Formica polyctena (Förster) / Studies on the Pheromones of Formica polyctena (Förster)
Authors: Francke W. , Bühring M. , Horstmann K. 
Published: August 2018

Abstract
Methyl-3-isopropylpentanoate is identified from the heads of workers and in higher concentration from heads of old queens of Formica polyctena (Förster). In laboratory bioassays this terpenoid ester showed a strong aggression inhibiting effect. While in the abdomina of workers the alarm pheromone undecane is the main compound it is almost completely absent in the abdomina of old queens.
Chlorophyll Biosynthesis: Various Chlorophyllides as Exogenous Substrates for Chlorophyll Synthetase
Authors: Benz Jürgen , Rüdiger Wolfhart 
Published: August 2018

Abstract
The esterification of various chlorophyllides with geranylgeranyl diphosphate was investigated as catalyzed by the enzyme chlorophyll synthetase. The enzyme source was an etioplast membrane fraction from etiolated oat seedlings (Avena sativa L.). The following chlorophyllides were prepared from the corresponding chlorophylls by the chlorophyllase reaction: chlorophyllide a (2) and b (4), bacteriochlorophyllide a (5), 3-acetyl-3-devinylchlorophyllide a (6), and pyrochlorophyllide a (7). The substrates were solubilized with cholate which reproducibly reduced the activity of chlorophyll synthetase by 40-50% . It was found that the following compounds were good substrates for chlorophyll synthetase: chlorophyllide a and b, 3-acetyl-3-devinylchloro-phyllide a, and pyrochlorophyllide a. Only a poor or no reaction was found with protochloro­phyllide, pheophorbide a, and bacteriochlorophyllide. This difference of reactivity was not due to distribution differences of the substrates between solution and pelletable membrane fraction. Furthermore, no interference between good and poor substrate was detected. Structural features necessary for chlorophyll synthetase substrates were discussed.
Initiation of Protein Synthesis in Yeast: Binding of Met-tRNAi
Authors: Kreutzfeldt Christian 
Published: August 2018

Abstract
Conditions for the binding of Met-tRNAi to 40 s ribosomal subunits and to proteins isolated out of the yeast ribosomal KCl wash were investigated. Sucrose density gradient experiments revealed that binding of Met-tRNAi to 40 s ribosomal subunits was catalyzed in a AUG and GTP dependent reaction. Binding of Met-tRNAi to proteins of the ribosomal KCl wash as assayed by the Millipore filter technique was found to be independent of AUG, GTP and 40 s ribosomal subunits. Additions of GTP yielded only slight stimulation, whereas Mg2+ caused dissociation of complexes. It was concluded that these reactions were most likely catalyzed by initiation factor eIF-2 although stimulation by GTP did not occur.
Molekulare und kinetische Charakterisierung der Xanthin-Dehydrogenase aus dem phototrophen Bakterium Rhodopseudomonas capsulata / Molecular and Kinetic Characterization of Xanthine Dehydrogenase from the Phototrophic Bacterium Rhodopseudomonas capsulata
Authors: Aretz Werner , Kaspari Herwig , Klemme Jobst-Heinrich 
Published: August 2018

Abstract
The structural and kinetic properties of xanthine dehydrogenase (EC 1.2.1.37) from the facultative phototrophic bacterium Rhodopseudomonas capsulata were studied. The enzyme was fully induced when hypoxanthine or xanthine, but less effectively when uric acid served as nitrogen source during growth. The enzyme was purified about 2300-fold from cells grown photosynthetically with hypoxanthine as N-source by using ammoniumsulfate precipitation, gel filtration, ion-exchange and affinity chromatography. The molecular weight as determined by gel filtration throug Sephacryl S-300 was 345000. Subunit analysis by sodium dodecyl sulfate gel electrophoresis suggested a composition of four identical subunits with a molecular weight of 84000. The enzyme contained 2 flavin, 2 molybdenum and 8 iron-sulfur groups per mol. The turnover number with hypoxanthine and NAD as substrates was 12000 min-1. Hypoxanthine, 1-methylhypoxanthine, 8-azahypoxanthine, xanthine, 1-methylxanthine, 2-hydroxypurine, 6,8-di-hydroxypurine, 5-azacytosine and 5-azauracil served as electron donors. The most effective electron acceptor was NAD. The kinetic constants (Km) were (in μm): 52.5 (hypoxanthine); 32.5 (xanthine) and 61.2 (NAD). Various purine compounds inhibited the enzyme competitively in respect to hypoxanthine as substrate. Although reduction of uric acid to xanthine was not detected by using purified enzyme preparations, in vitro-experiments with 14C-labelled uric acid indicated that the enzyme xanthine dehydrogenase participates in uric acid degradation in Rps. capsulata. According to their electrophoretic mobilities, the xanthine dehydrogenases isolated from hypoxanthine-and uric acid-grown cells were identical.
Altered Heme Environments in Opossum and Rabbit Methemoglobins
Authors: John Maliyakal E. , DuBois Raymond N. , Waterman Michael R. 
Published: August 2018

Abstract
The effect of pH and inositol hexaphosphate (IHP) on the symmetry of the heme environments in opossum (Didelphius marsupialis) and New Zealand White rabbit hemoglobins has been studied using electron spin resonance (ESR). Each methemoglobin is found to contain two different heme environments as detected by the rhombicity observed in the ESR spectrum. In both cases the rhombic nature of the ESR spectrum is influenced by pH and IHP binding, although in the case of rabbit methemoglobin the high spin ESR signal disappears above pH 8.0. In both hemoglobins, amino acid alterations in the α-chains are known to affect the properties of the ferrous derivatives. It is concluded that these alterations also provide the basis for the ESR spectral properties observed with the methemoglobins.
A H+/Ca2+ Antiporter in Membranes of Microsomal Vesicles from Maize Coleoptiles, a Secondary Energized Ca2+ Pump
Authors: Hager A. , Hermsdorf P. 
Published: August 2018

Abstract
Microsomal vesicles prepared from the ER and the Golgi apparatus of maize coleoptiles possess an ATP-fueled, Cl--dependent proton pump which can cause an intravesicular acidifica­tion of the vesicles (A. Hager and M. Helmle, Z. Naturforsch. 36 c, 997 (1981); A. Hager et al., Z. Naturforsch. 35 c, 783-793 (1980)). This acidification is very specifically inhibited by Ca2+. The inhibition is already distinct at concentrations of 30 μᴍ. While 10-fold higher concentrations of La3+ produce similar effects, Mg2+ remains ineffective even at very high concentrations.
If Ca2+ is added after acidification of the vesicles, a rapid H+-efflux proportional to the amount of Ca2+ added characterizes the first reaction phase. In the second reaction phase acidification within the vesicles commences anew, however, at a reduced rate.
If Ca2+ is added to vesicles whose proton pump has been inhibited by DCCD, the first reaction phase remains unchanged, while the acidification in the second reaction phase does not set in, and only a leak out of protons is observed.
These results give support for a H+/Ca2+-antiporter mechanism which can function as a secondary energized Ca2+-pump and regulate the Ca2+-concentration in the cytoplasm.
Comparative Binding of Photosystem II — Herbicides to Isolated Thylakoid Membranes and Intact Green Algae
Authors: Laasch Henrik , Pfister Klaus , Urbach Wolfgang 
Published: August 2018

Abstract
The binding of the photosystem II herbicides diuron (DCMU), atrazine (s-triazine), ioxynil and dinoseb (substituted phenols) to isolated spinach thylakoids was saturated in less than 2 min in the dark. In intact cells of the green alga Ankistrodesmus b. it took 10 to 20 min to reach the binding equilibrium.
Binding affinity of diuron, atrazine, dinoseb, measured as equilibrium binding constants, was found to be comparable in isolated thylakoids and intact algal cells. For ioxynil, reduced binding affinity was observed in algae.
The concentration of binding sites in thylakoids and intact cells was determined to be 300-500 chl/inhibitor binding site, suggesting a 1:1 stoichiometry between bound herbicide and electron transport chains. In intact cells only the phenol herbicides ioxynil and dinoseb showed increased concentrations of binding sites.
Strong correlation of herbicide binding and inhibition of electron transport was found for diuron in isolated thylakoids and intact cells. In thylakoids this is valid also for atrazine and dinoseb. For ioxynil a difference between the amount of binding and inhibition was found. This correlation of herbicide binding and inhibition proves that binding specifically occurs at the inhibition site at photosystem H.
In addition to the specific binding, for all four herbicides studied, (except for ioxynil in thylakoids) unspecific binding was observed in thylakoids as well as in algae, which was not related to inhibition.
Effect of Lithium Chloride on the Circadian Rhythm in the Flight Activity of the Microchiropteran Bat, Taphozous melanopogon
Authors: Subbaraj Ramanujam 
Published: August 2018

Abstract
We have performed experiments on the influence of Li+ offered through drinking water i) on the period length (τ) of the rhythm in the flight activity of bats under LL and ii) on phase angles during entrainment under LD cycles. Bats subject to entrainment exhibited no qualitative and quantitative change in Ψ values after Li+ treatment. In contrast the ingestion of Li ions by bats under free-running conditions shortens the τ of the bat rhythm by an amount that is a function of period length prior to ingestion, τ is, thus homeostatically conserved in the face of Li administra­ tion in bats.
Sinapine as a Supply of Choline for the Biosynthesis of Phosphatidylcholine in Raphanus sativus Seedlings
Authors: Strack Dieter 
Published: August 2018

Biosynthesis of phosphatidylcholine in young seedlings of Raphanus sativus is supplied with choline from degradation of the seed constituent sinapine (sinapoylcholine). This conclusion has been deduced from the following results:
(1) Raphanus sativus seedlings accumulate approx. 70 nmol phosphatidylcholine which may be relevant for the consumption of choline, liberated during hydrolysis of approx. 130 nmol sinapine.
(2) [14C]choline and [14C]ethanolamine, taken up by germinating Raphanus seeds, are exclusively consumed in the biosynthesis of phosphatidylcholine and phosphatidylethanolamine, respectively.
(3) Pulse-chase experiments with seedlings at different germination stages show a reduced [14C]choline incorporation into phosphatidylcholine at the time when degradation of sinapine occurs, obviously as a result of an isotope dilution by an increase of the endogenous choline pool.
(4) After [14C]choline pulse to immature seeds, during the process of seed maturation most of the activity taken up is incorporated into accumulating sinapine and approx. 50% compared to this into phosphatidylcholine. During seedling development the quantity of labelled sinapine rapidly decreases as a result of sinapine degradation with a concomitant label increase in free choline, phosphorylcholine, and phosphatidylcholine. Approx. 50% of the choline liberated from sinapine, is consumed in the biosynthesis of phosphatidylcholine.
High performance liquid chromatographic analyses of phosphatidylcholine during Raphanus germination revealed that this phospholipid might be a metabolically active compound. Changes in the absorptivity of this compound at 210 nm indicate changes in the degree of unsaturation in the fatty acyl groups
Physico-Chemical Characteristics of DNA Chromatin Fractions from Calf Thymus
Authors: Gawrońska Maria , Kulamowicz Irena , Oliński Ryszard , Żbikowska Małgorzata , Walter Zofia 
Published: August 2018

Abstract
Two DNA fractions with different physico-chemical properties were obtained from calf thymus. On the basis of our results as well as some literature data we suppose that these are eu-and heterochromatin DNAs.
Flavonoidglycoside und Pyrone bei Aniba-Arten (Lauraceae) / Flavonoid Glycosides and Pyrones in Aniba Species (Lauraceae)
Authors: Koch V. , König W. A. 
Published: August 2018

Abstract
The distribution of flavonoid glycosides and pyrones are investigated for 3 Aniba species. The intraspecific variation of these compounds is shown for Aniba rosaeodora. 6-(3′,4′-methylendioxy-trans-styryl)-2-pyrone and 6-(3′,4′-dimethoxy-trans-styryl)-2-pyrone are seldom occuring natural compounds and were proved for A. permollis for the first time. The phylogenetic aspects are briefly discussed.
Coα/Coβ-Isomerie der am Kobalt methylierten Corrinoide. Über die CD-und ORD-Spektren einiger Isomerenpaare / Coα/Coβ-Isomerism of the Cobalt Methylated Corrinoids. CD and ORD Spectra of Several Isomer Pairs
Authors: Moskophidis Matthäus 
Published: August 2018

Abstract
The CD and ORD spectra of the Coar-and Co/β-methyl isomers of cobalamin, 2-methylthio-adenyl cobamide (factor S), cobyric acid and p-kresyl cobamide (factor lb) were recorded in water and acidic solution. In complete and incomplete (nucleotide free) (Coar-methyl)-corrinoids the axial ligands CH3 and H2O are unalterable (fixed) within a wide range of pH (about 1 to 12) at room temperature in the dark. Thus the spectra in this pH range are constant at X > 350 nm; spectral differences at X < 350 nm are effects of the nucleotide bases. The spectra of complete "base-on" (Co/β-methyl)-corrinoids are, like the spectra of (Coa-methyl)-corrinoids, at X > 350 nm not dependent on the nucleotide base. If the nucleotide base is not coordinated ("base-off'), the spectra change strikingly and at X > 350 nm are nearly identical with those of incomplete corrinoids e. g. cobyric acid.
Halbseiten-Reaktivität der Glycerinaldehyd-3-phosphat Dehydrogenase aus Kaninchen-Skelettmuskel mit Strukturanalogen von NAD / Half-of-the-Sites Reactivity of Glyceraldehyde-3 Phosphate Dehydrogenase from Rabbit Muscle with Structural Analogs of NAD
Authors: Ehrenfeld Michael , Jeck Reinhard , Klatte Walter , Kühn Norbert , Woenckhaus Christoph 
Published: August 2018

Abstract
Alkylating NAD-Analogs, Glyceraldehyde-3 Phosphate Dehydrogenase, Half-of-the-Sites Reactivity co-(3-Bromoacetylpyridinio)alkyldiphosphoadenosines with alkyl chain lengths of 2 -6 me­ thylene groups inactivate glyceraldehyde-3 phosphate dehydrogenase from rabbit muscle. Half-of-the-Sites reactivity is observed in each case: The analogs are covalently bound to highly reactive cysteine residues in two of the four subunits. The remaining two subunits still bind N AD and the reactive SH-groups, although modified by SH-reagents of low molecular weight are not labeled by any of the brominated coenzyme models. This behaviour may be explained by the assumption, that the modification of 2 subunits induces structural changes in the neighboured unoccupied subunits which prevent any attack on reactive cysteine residues caused by fixation and orientation of the bromoketo-coenzyme analog when bound to the active center. Structural similarities of the covalently bound coenzyme analogs in the active center and the native ternary GAPDH-NAD-substrate complex suggest that half-of-the-sites reactivity is a natural characteristic of the enzymes catalytic mechanism.