bluuebunny/crossref_metadata_2025 huggingface dataset:
On the Reactivity of Pyridoxal-5'-phosphate with Yeast tRNAPhe and tRNATyr
Authors: Okabe Nobuo , Cramer Friedrich
Published: August 2018

Yeast tRNAPhe, Yeast tRNATyr, Pyridoxal-5'-phosphate Yeast tRNAPhe and tRNATyr were reacted with the fluo­ rescent reagent pyridoxal-5'-phosphate and the modified tRNAs were analysed with respect to the number and posi­ tion of modified nucleosides and with respect to amino-acylation.

a) Following the intrinsic fluorescence of pyridoxal-5'-phosphate, the treatment of tRNATyr with increasing amounts of pyridoxal-5'-phosphate revealed about 50 mol of reagent or a even higher number bound per one mol of tRNATyr. After borohydride reduction (in order to stabilize the linkage) of this modified tRNATyr and purification with reverse phase

b) Both tRNATyr and tRNAPhe treated with pyridoxal-5'-phosphate and reduced exhibited almost unchanged aminoacylation as compared to the unmodified tRNAs.

c) Pyridoxal-5'-phosphate treated and reduced tRNAPhe and tRNATyr were digested with ribonuclease T1 and the resulting oligonucleotides were separated. However, no flu­ orescent oligonucleotide and no difference to an oligonucleotide pattern obtained from unmodified tRNA were observed.

Thus, pyridoxal-5'-phosphate might have been bound to the highly purified yeast tRNAPhe and tRNATyr samples either via an unstable linkage or not covalently. This result is controversial with respect to the specific reaction of pyridoxal-5'-phosphate with unfractionated tRNAs from colon carcinoma and tRNAs from E. coli as reported in the literature.
Anion Metabolism as Correlated with the Volume Changes of Guard Cell Protoplasts
Authors: Schnabl H.
Published: August 2018

Isolated and purified guard cell protoplasts of starch-containing (Vicia faba) and starch-lacking (Allium cepa) stomata were used to study the metabolism of malate and Cl- anions as correlated with the K+-induced swelling of protoplasts. The correlation between swelling and malate synthesis in starch-containing and the inhibition of this correlation in starch-lacking guard cell protoplasts were demonstrated. A model system was proposed involving the role of malate and its place of synthesis in these two contrasting stomatal types.
Effects of 3-(3,4-Dichlorophenyl)-N-N'-Dimethylurea on Oxygen Evolution and Fluorescence by Whole Filaments and Isolated Thylakoids of the Cyanobacterium Anabaena cylindrica
Authors: Codd Geoffrey A. , Schmid Georg H.
Published: August 2018

The site of inhibition of DCMU against photosystem II in the cyanobacterium (Blue-green alga) Anabaena cylindrica was examined in electron transport and fluorescence studies. Isolated thylakoids catalyzed silicomolybdate photoreduction using H2O as electron donor; the steady-state reaction was completely inhibited by DCMU. This reaction is insensitive to DCMU in chloroplasts, since silicomolybdate accepts electrons from the primary photosystem II acceptor, and thus before the site of action of DCMU in higher plants. DCMU did not increase the steady-state level of fluorescence by inact A. cylindrica, nor affect the monophasic fluorescence induction, with or without dithionite, in contrast to the DCMU-dependent stimulation of steady-state fluores­cence and replacement of rapid initial transients by a monophasic rise in Chlorella. Fluorescence by isolated cyanobacterial thylakoids was lowered by the electron acceptors silicomolybdate, p- benzoquinone, ferricyanide and anthraquinone-2-sulfonate, and not restored by DCMU addition, in contrast to results obtained with tobacco chloroplasts. Together with previous Findings that di- phenylcarbazide-dependent photosystem II activity of A. cylindrica thylakoids is insensitive to DCMU. The data indicate that the principal site of action of the inhibitor lies on the O2-evolving side of photosystem II in this cyanobacterium.
Immunological Studies of Catechol Methyltransferase from the Yeast Candida tropicalis
Authors: Veser Joseph , Thomas Helmut
Published: August 2018

Immunization of rabbits with purified catechol methyltransferase from Candida tropicalis yielded a potent antiserum. Ouchterlony double diffusion analysis showed a single precipitin line. There was no cross reactivity with the catechol methyltransferase from rat and bovine liver. Specific antigen-antibody interaction was demonstrated by a potent inhibitory effect of the antibody on the yeast enzyme. Immunological titration and quantitative precipitin reaction of the enzyme showed that the maximum amount of precipitable complex occurred at the equivalence point where enzyme activity was completely inhibited.
Running Activity Patterns of Females and Last Larval Instars of the Cockroach Leucophaea maderae
Authors: Wiedenmann Gottfried , Martin Wolfgang
Published: August 2018

Virgin females of Leucophaea maderae reveal a circadian rhythm in their locomotor activity which is superimposed by the ovarial cycle. Locomotor activity of last larval instars does not exhibit a circadian pattern.
Ein neues Kämpferolacylglycosid aus Phyllitis scolopendrium / A New Acylated Kaempferol Glycoside from Phyllitis scolopendrium
Authors: Karl Christian , Pedersen Peter Alsted , Müller Gerhard
Published: August 2018

From methanolic extracts of fresh aerial parts of Phyllitis scolopendrium (L.) Newm. a new flavonoid, kaemp­ ferol 3-O-β-{(4-O-caffeyl-3-O-β-glucosyl)-glucoside}-7-O-rhamnoside, was isolated and the structure determined by means of spectroscopic methods including 13C-NMR, and enzymatic hydrolysis.
Enzymatic Synthesis o f Sinapoyl-L-M alate from 1-Sinapoylglucose and L-M alate by a Protein Preparation from Raphanus sativus Cotyledons
Authors: Tkotz Norbert , Strack Dieter
Published: August 2018

Protein preparations from cotyledons of Raphanus sativus transfer the sinapoyl moiety of 1 -sinapoylglucose to L-malate to form sinapoyl-L-malate. To our knowledge this is the first time that this type of reaction has been found to be involved in phenylpropanoid depside formation. Most acylation reactions have so far been demonstrated to depend on acyl-CoAs and only one example is known describing 1-O-acyl sugar derivatives as acyl donors.
The Primary Structure o f the Monomeric Hemoglobin (Erytrocruorin) Component CTT IV o f Chironomus thummi thummi (Insecta, Diptera)
Authors: Pfletschinger J. , Plagens H. , Braunitzer G.
Published: August 2018

The primary structure of the monomeric hemoglobin (Erythrocruorin) CTT IV from larvae of Chironomus thummi thummi (Diptera) is presented. The sequence was determined automatically. The primary structure is com­ pared with human α-globin-chain.
Purification and Properties of a New Enzyme from Evernia prunastri, which Reduces ʟ-Usnic Acid
Authors: Estévez M. P. , Cátedra de Fisiología Vegetal, Facultad de Biología, Univers E. , Olmeda L. , Pérez F. J.
Published: August 2018

new enzyme, usnic acid dehydrogenase, which catalyzes the reduction of ʟ-usnic acid, has been isolated from cell-free extract of Evernia prunastri thallus. Purification of the enzyme (approx. 150-fold with a recovery of 42%) can be achieved by using gel adsorption and gel filtration techniques. The apparent molecular weight of the enzyme is 450000. Cofactor requirement is restricted to NADH. Kinetics of the enzyme show an allosteric behaviour for both ʟ-usnic acid and NADH. Structure of the reaction product is described.
Medium-Induced Formation of Indole Alkaloids and Concomitant Changes of Interrelated Enzyme Activities in Cell Suspension Cultures of Catharanthus roseus
Authors: Knobloch K.-H. , Hansen B. , Berlin J.
Published: August 2018

Recently medium conditions have been developed which stimulate the formation of the indole alkaloid ajmalicine in cell suspension cultures of Catharanthus roseus [6]. When cells were subjected to these conditions the alkaloid accumulation was preceded by a 12-fold increase of the specific activity of tryptophan decarboxylase. The enzyme activity showed a maximum two days after the cell transfer into the induction medium and subsequently declined. In contrast the activity of strictosidine synthase, the enzyme condensing tryptamine and secologanin, was present over the entire measuring period at a constant level. The intracellular content of tryp­tamine and ajmalicine increased during a period of 6 days after cell transfer and reached a plateau after that time. A possible regulatory function of tryptophan decarboxylase in indole alkaloid biosynthesis is discussed.
Pressure, Temperature and pH Dependence of the Absorption Spectrum of Reduced Nicotinamide Adenine Dinucleotide
Authors: Jaenicke Rainer , Liidemann Hans-Dietrich , Schmid Gerhard
Published: August 2018

Enzymological studies at high hydrostatic pressure generally involve temperature, pH and pressure as variables, owing to the effect of adiabatic compression and the ionization volume of the buffer system. In the case of NAD dependent oxidoreductases this implies that the extinction coefficient of the coenzyme may be affected by p, T and pH, apart from the spectral change accompanying the redox reaction.

Measurements of the pressure dependence of the absorbance of NADH show a slight red shift and a 1% decrease (3% increase) of the absorbance at 339 nm (360 nm) at 2 kbar. The pH depen­dence at the given wavelengths amounts to -(2.4 ± 0.1)% per pH unit (25 °C), while the intrinsic temperature effect (after correction for thermal expansion) is of the order of -0.2% per degree (20-30 °C).

Applying buffers with negligible ionization volume, 366 nm is the optimum wavelength for high pressure studies up to 2 kbar because here the pressure dependent spectral changes of the NADH absorption vanish.
Trypsin-Mediated Removal of Herbicide Binding Sites within the Photosystem II Complex
Authors: Steinback Katherine E. , Pfister Klaus , Amtzen Charles J.
Published: August 2018

Trypsin treatment of isolated chloroplast thylakoids resulted in a step-wise modification of surface exposed membrane polypeptides. Early effects of the protease action resulted in a decrease in inhibitory activity of atrazine, diuron, pyrazon, and bromacil, but an initial increase in the activity of bromnitrothymol and dinoseb. Direct measurements of atrazine binding demonstrated that decreased inhibitory activity corresponded to a decreased binding affinity in the treated membranes. Longer term effects of trypsin caused removal of atrazine binding sites and a concomitant block of electron transport chains. The data are consistent with a concept that the traizine receptor protein is a component of the electron transport chain which is successively degraded in two or more steps by protease attack.

Polyacrylamide gel electrophoresis of trypsin-treated membranes and sub-membrane fragments derived from these membranes revealed that several polypeptides are membrane surface exposed. The involvement of a 32000 dalton polypeptide in creating the atrazine binding site is discussed.
Binding of Polylysine and Ethidium Bromide to Nucleosomal DNA: Comparison of Biochemical and Electron Microscopical Results
Authors: Marx Ruth , Doenecke Detlef
Published: August 2018

Ethidium bromide and polylysine interact with nucleosomal DNA and lead to changes of biochemical properties and to morphological changes as to the distance between the two core particles of a nucleosome dimer.

With increasing polylysine concentration, the buoyant density of nucleosomes decreases and the accessibility of the nucleosomal DNA to micrococcal nuclease is lowered. Electron microscopy of polylysine treated nucleosome dimers reveals a shortening of the intemucleosomal distance as compared with controls.

Treatment of nucleosomes with ethidium bromide leads to an enhanced accessibility of the nucleosomal DNA to micrococcal nuclease. Electron microscopy reveals an increase in length of the DNA connecting the two nucleosome cores in the presence of the dye.

Both the binding of polylysine and the treatment with ethidium bromide apparently do not affect the histone arrangement within the nucleosome core as suggested by chemical cross-linking of histones and DNA with formaldehyde, and no obvious morphological changes of the nucleosome cores can be observed.
Cytochalasin B-Induced ATPase Activity of Actin: Dependence on Monomer Concentration
Authors: Dancker Peter , Kliche Agnes
Published: August 2018

We simultaneously measured polymerization and ATPase activity of actin induced by cytochalasin B. It was found that under all conditions tested, ATPase activity was proportional to the concentration of actin which was unpolymerized. In addition, it was found that conditions increasing ATPase activity also increase the velocity of polymerization. From this we conclude that CB-induced ATPase activity is a property of the actin monomers and that the “readiness” of the monomers to hydrolyze ATP is correlated with an increased capacity of the monomers to polymerize.
Investigations on Hoya species. VIII*. Leaf Flavonols and Di-C-glycosylflavones
Authors: Niemann Gerard J. , Dellamonica Georgette , Chopin Jean
Published: August 2018

Nine Hoya species were investigated for their leaf flavonoids. Four species contained flavonols identified as the 3-diglycosides of kaempferol and/or isorhamnetin, in some species acylated with ferulic and/or p-cumaric acid. Five species had no flavonols but were rich in flavones. Identified were: schaftoside, isoschaftoside, di-C-arabino-sylapigenin and vicenin 2.
Steroide menschlicher Thymi / Steroids of Human Thymi
Authors: Reisch Johannes , El-Sharaky Ahmed S.
Published: August 2018

Analysis of human thymus steroids by liquid-gel chro­matography and gas chromatography-mass spectrometry revealed in dependence of age 4-pregnene-3,20-dione, 11β-hydroxy-4-pregnene-3,20-dione, 7β-hydroxycholesterol, and 7-ketocholesterol. 11β-Hydroxy-4-pregnene-3,20-dione should be the inhibitor of immune maturation.
Gaschromatographic, Mass-and Infrared-Spectrometric Identification of Cyclic Adenosine-3': 5'-monophosphate (c-AMP) in Maize Seedlings (Zea mays)
Authors: Janistyn Boris
Published: August 2018

Gaschromatographic, mass- and infrared-spectrometric evidence is presented for the identification of adenosine-3':5'-monophosphate (c-AMP) in maize seedlings (Zea mays).

The genuine c-AMP content could be quantitated by GC-detection and refere to authentic c- AMP standards
Molecular Characterization of Glutamine Synthetase from the Nitrogen-Fixing Phototrophic Bacterium Rhodopseudomonas palustris1
Authors: Alef Kassem , Burkardt Hans-Joachim , Horstmann Hans-Joachim , Zumft Walter G.
Published: August 2018

The phototrophic bacterium Rhodopseudomonas palustris assimilated ammonium via glutamine synthetase and glutamate synthase. Diazotrophic and ammonium-grown cells had high levels of both enzymes, whereas enzymes of alternative assimilatory pathways were absent or had only low activities. Glutamine synthetase was purified to electrophoretic homogeneity within three steps by dye-ligand and ion exchange chromatography. Electron microscopy revealed a dodecameric molecular entity which was in accordance with parameters derived from electrophoretic techniques. The molecular weight of the enzyme monomer was 55 800; that of the dodecamer 670 000. The amino acid composition of R. palustris glutamine synthetase was determined and compared by a statistical method with other known enzyme compositions from prokaryotic and eukaryotic origins
Receptor Specificity and Threshold Concentration in Chemotaxis of the Phaeophyte Cutleria multifida
Authors: Boland Wilhelm , Jakoby Karin , Jaenicke Lothar , Müller Dieter G. , Fölster Eisbet
Published: August 2018

Sexual reproduction has a decisive function during the life cycle of all organisms. In the marine brown alga Cutleria multifida, multifidene (1), a low molecular weight olefinic hydrocarbon, has been recognized as a chemical messenger for gamete union. Comparative activity tests with 32 specially designed synthetic analogous of the natural attractant demonstrate the high specifity and low threshold concentration (6.5 × 10-12 mol/L) of the gamete’s receptor system toward its natural signal (1). The findings establish the double bonds of multifidene (1) as the molecular coordination points in the messenger-receptor interaction. A tentative model is presented, which takes into account the evidence, that unpolar, but highly polarizable functional groups in the correct spatial arrangement are necessary for maximal mutual interaction
Purification of Murine and Feline Type-C Virus Envelope Polypeptides as Micellar Protein Complexes
Authors: Schneider Josef , Falk Heinz , Hunsmann Gerhard
Published: August 2018

A technique originally described for the isolation of Friend leukaemia virus envelope polypeptides [1] yields equivalent structures from Moloney leukaemia, AKR and BALB/c xenotropic virus as well as feline leukaemia virus. The envelope polypeptides are obtained as micellar protein complexes, named rosettes. Rosettes of the five m am malian type-C viruses examined are indistinguishable by electron microscopy. Separation of these aggregates in polyacrylamide gel electrophoresis under nonreducing conditions reveals a glycoprotein of about 85 000 d as their major component. Tryptic peptide analyses identify the viral origin of these polypeptides and emphasize strain specific differences in their primary structure
In Vivo Control of Glutamine Synthetase in the Facultative Phototrophic Bacterium Rhodopseudomonas sphaeroides
Authors: Engelhardt Harald , Klemme Jobst-Heinrich
Published: August 2018

In vivo control of glutamine synthetase (GS) in the facultative phototrophic bacterium Rhodopseudomonas sphaeroides was studied. The enzyme was partially purified from cells grown photosynthetically in ammonium-malate-medium. Its catalytic properties were characteristically changed by incubation with phosphodiesterase indicating an in vivo regulation by adenylylation/deadenylylation. Adenylylation states of GS were measured as a function of variations in the nitrogen source and the light intensity during photosynthetic growth.
Preparation and Properties of Chromopeptides from the Pfr Form of Phytochrome
Authors: Thümmler Fritz , Brandlmeier Thomas , Rüdiger Wolfhart
Published: August 2018

Chromopeptides were prepared from the Pfr form of phytochrome by pepsin digestion. After separation from colorless peptides and Pr peptides by column chromatography, spectral characteristics of this Pfr peptide were determined (λ1
max = 610nm, λ2
max = 380nm in acid methanol). Irradiation of Pfr peptide produces Pr peptide without liberation of a detectable compound. The Pfr peptide is more sensitive to oxidation and reduction than the Pr peptide. Oxidation with iodine and reduction with dithionite leads to partial chemoconversion of the Pfr peptide to the Pr peptide. The results favor the model of cis-trans isomerization for the Pr ⇌ Pfr transformation.
Sukkulenz — Induktion bei Kalanchoe bloßfeldiana im Langtag durch eine lipophyle Fraktion aus blühenden Kalanchoe und MS-Identifikation von Pterosteron / Succulence — Induction in Kalanchoe bloßfeldiana under Long-Day Conditiones by a Lipophilic Fraction out of Flowering K alanchoe and MS-Identification of Pterosterone
Authors: Janistyn Boris
Published: August 2018

Succulence-induction in Kalanchoe bloßfeldiana is demonstrated under long-day condition by application of a lipophilic fraction from flowering Kalanchoe. Different preparative TC separation steps yielded a partial purification of this fraction and the MS-identification of pterosterone (10-6 m), which is not necessary correlated with the above described physiological activity.
The Isolation of Antibodies Specific for 5-Methyl-Cytidine-Bovine Serum Albumin
Authors: Mastronicolis Sofia K. , Kapoulas Vassilios M. , Kröger Hans
Published: August 2018

By coupling 5-Methyl-cytidine to bovine serum albumin, a conjugate containing 18 mol of 5-Methyl-cytidine per mol of BSA was prepared. Antibodies to this conjugate were produced by immunization of rabbits. Specificity of the antibody was assesed by gel diffusion in agar containing excessive amounts of the carrier BSA. A slight cross-reactivity with cytidine was eliminated by adsorption on the cross-reacting antigen.

The isolation of 7 S immunoglobulin from the total globulin fraction was accomplished by chromatography on DEAE Sephadex-A-50, and a method for the rapid quantitation of the antibodies showed that 12.7% of the IgG protein are monospecific against 5-Methyl-cytidine bovine serum albumine.
Vascular Specialization in Fish, but No Evidence for Lymphatics
Authors: Vogel Walter O. P. , Claviez Michael
Published: August 2018

Blood distribution in the systemic circulation of bony fishes is effected by a dualistic construction of the vasculature: A secondary arterial system originates from the well known (primary) arteries by multiple root-like shunt vessels. These secondary arteries and the vessels they supply should no longer be regarded as lymphatics. After an intensive search for unequivocally lymphatic vessels in fish, it appears doubtful whether there are any at all in this class of vertebrates.
Effect of Hydrogen Ion Concentration on the Absorption Spectrum and Fluorescence Life Time of Chloroplasts
Authors: Brody Seymour Steven , Gregory Richard P. F.
Published: August 2018

Subjecting pea chloroplasts to hydrogen ion gradients results in small but significant changes in the absorption and circular dichroic spectra. The relative intensities of the fast and slow fluorescence decays are modified by the hydrogen ion concentration. The life time of the slow components is only slightly altered. At pH 11 the circular dichroic peak at 690 nm, assigned to Photosystem I chlorophyll-protein complex, is clearly resolved. Also, there is a splitting of the peak at 650-640 nm, attributed to Photosystem II chlorophyll-protein. At pH 3.9 splitting of the 650-640 nm peak is observed. There is also a positive component at 705 nm which may be associated with an aggregated form of chlorophyll or pheophytin. The changes in absorption spectra are determined by measuring the difference in spectra between identical chloroplasts suspensions one at pH 7.6 and the other at alkaline or acidic pH. At pH 2 and pH 3.7 there are time dependent increases in absorbance at 430, 445, 520, 538, 670 nm, and a decrease in absorbance at 606 nm. After a delay of 11 min at pH 2, there is also an increase in absorbance at 700 nm. The latter is interpreted as possible formation of aggregated pheophytin. At pH 11.0 there are time dependent increases in absorbance at 638, 454 and 440 nm, and decreases in absorbance at 675, 660, 508 and 472 nm. The changes in absorbance of the pigment around 520 nm (associated with an electrochromic effect) is interpreted as resulting from a leakage of hydrogen ion across the thylakoid membrane. The spectral changes that occur during the first 9 min are reversible. After the chloroplasts have incubated for more than 15 min most of the spectral changes are not reversible.
Oxidation of Flavanones to Flavones with Flower Extracts of Antirrhinum majus (Snapdragon)
Authors: Stotz G. , Forkmann G.
Published: August 2018

Enzyme preparations from flowers of Antirrhinum majus catalysed the oxidation of naringenin to apigenin and of eriodictyol to luteolin. Enzyme activity was found to be localized in the microsomal fraction. The reaction required NADPH as cofactor and had a pH optimum of about 7.0. The NADPH-dependent microsomal enzyme activity was also present in flower extracts of other flavone-producing plants, whereas flower extracts of plants which lack flavones were found to lack also this enzyme activity.
Carotenoids in the Stick Insect, Ectatosoma tiaratum Isolation of β,Ɛ-Caroten-2-ol and β,Ɛ-Caroten-2-one
Authors: Kayser Hartmut
Published: August 2018

2-Oxo-carotenoids, 2-Hydroxy-carotenoids, [uC]/β-Carotene, Metabolism, Stick Insects The carotenoids of the stick insect, Ectatosoma tiaratum, were studied by spectroscopic and chemical methods. The β,β-type pigments are β,β-carotene, β,β-caroten-2-one, β,β-caroten-2-ol, β,β-carotene-2,2'-dione, 2'-hydroxy-β,β-caroten-2-one, β,ε-carotene-2,2'-diol, 3,4-didehydro-β,β-carotene-2,2'-dione, 2'-hydroxy-3,4-didehydro-β,β-caroten-2-one, and 3,4,3',4'-tetradehydro-β,β-carotene-2,2'-dione. In addition, the following β,ε-type pigments were identified: β,ε-carotene, β,e-caroten-2-ol, and β,e-caroten-2-one. This is the first report on the occurrence of β,e-caroten-2-ol in an animal and of β,ε-caroten-2-one in nature at all. On treatment with BF3 in chloroform β,ε-caroten-2-ol is dehydrated to a specific product with the proposed structure of 2,3-didehydro-4,7'-retro-β, e-carotene.

The biogenesis of the β,β-type carotenoids from β,ε-carotene is demonstrated by feeding [14C]β-carotene to the insects. Radiolabel was incorporated into all major metabolites of this type. The metabolism of carotenoids in stick insects is discussed applying the "half-molecule sub­ strate" hypothesis to the enzymic transformations of the pigments.
Reassociation of Lactic Dehydrogenase from Pig Heart Studied by Cross-Linking with Glutaraldehyde
Authors: Bernhardt Günther , Rudolph Rainer , Jaenicke Rainer
Published: August 2018

Cross-linking with glutaraldehyde has been successfully applied in order to analyze the kinetics of reassociation of oligomeric enzymes (R. Hermann, R. Rudolph, and R. Jaenicke Nature 277, 243-245 (1979)). In the present study the assembly of lactic dehydrogenase from pig heart is investigated using this approach.

In order to eliminate perturbations caused by excessive folding reactions, acid dissociation was performed in the presence of 0.8 M Na2SO4 at 0°C . Under optimum conditions complete cross-linking of the tetrameric enzyme was achieved in less than 2 minutes.

Cross-linking during reconstitution proves the dimer to be the only intermediate of reasso­ ciation. The dimer → tetramer transition is found to be rate-limiting for both reassociation and reactivation, suggesting the tetramer to be the enzymatically active species.

The presence of monomers during reconstitution indicates that tetramer formation is preceded by a fast monomer-dimer equilibrium.

The kinetic model describing the experimental data

is characterized by an equilibrium constant K = 3 ± 1 · 107 liter · m ol-1, and a second-order rate constant k = 1.4 ± 0.2 · 104 liter · mol-1 · s-1.
Immunoadsorption as a Means for the Purification of Low Molecular Weight Compounds: Isolation of Ecdysteroids from Insects
Authors: Reum Lutz , Haustein Dieter , Koolman Jan
Published: August 2018

Ecdysteroid, Immunoadsorption of Steroids, Antiserum Specificity Two ecdysteroid-specific antisera, anti-ecdysone-albumin and anti-20-hydroxyecdysone-al-bumin, were induced in rabbits. The properties of both antisera were tested with a large number of ecdysteroids. The former antiserum was unique in its ability to discriminate between the moulting hormones, ecdysone and 20-hydroxyecdysone, whereas the latter had a broad specificity for ecdysone and several of its metabolites.

y-globulin fractions of both antisera were covalently linked to Sepharose 4B and used as immunoadsorbents. These were able to bind ecdysteroids from crude extracts of insects. Bound ecdysteroids could be eluted quantitatively from the adsorbents using 3 M sodium trichloroacetate. When a mixture of ecdysteroids which contained ecdysone and at least six different ecdysone me­ tabolites were run over a column with anti ecdysone immunoadsorbent only ecdysone and its hy-droxyderivatives 20-and 26-hydroxy ecdysone were bound to and subsequently eluted from the adsorbent. In contrast a column with anti-20-hydroxyecdysone immunoadsorbent retained most of the different ecdysteroids due to the broader specificity of the antibodies.

These immunoadsorbents provide the potential not only to purify ecdysteroids but also proteins crosslinked to ecdysteroids via photoaffinity labelling. It is well known that immuno-adsoiption is a powerful tool for the isolation of proteins. The results described here demonstrate that immunoadsorption may also be useful in the isolation of low molecular weight compounds of biological and medical interest.
Synthesis of Galloyl-Coenzyme A Thioester
Authors: Gross Georg G.
Published: August 2018

Galloyl-CoA, a potential intermediate in the biosynthesis of gallotannins, has been prepared via N-succinimidyl 4-O-β-ᴅ-glucosidogallate and 4-O-β-ᴅ-glucosidogalloyl-CoA. Besides a major absorption band at 261 nm, the UV-spectra of the purified thioester and its corresponding 4-O-glucoside contain a longer wavelenght absorption band due to the thioester linkage at 305 nm (galloyl-CoA) or at 290 nm (shoulder, glucosidogalloyl-CoA). The molar extinction coefficients ε of the two thioesters were determined via the iron-complex of 4-O-β-ᴅ-glucosidogalloyl hydroxamic acid; ε261-values of 19.5 × 106 [cm2 mol-1] and 21.5 × 106 [cm2 mol-1] were calculated for galloyl-CoA and its glucoside, respectively. Difference spectra, i.e. absorbance before esterolysis and after, revealed maximal absorption of the thioester bond at 310 nm (⊿ε = 7.4 × 106 [cm2 mol-1]) for galloyl-CoA and at 282 nm (⊿ε = 7.2 × 106 [cm2 mol-6]) for glu- cosidogalloyl-CoA. The two thioesters were further characterized by determining their half-lifes during hydroxylaminolysis and alkaline hydrolysis.
Growth Characteristics of Anaerobically Treated Ehrlich Ascites Tumor Cells after Reaeration as Studied by Combination of Flow Cytometry and Centrifugal Elutriation
Authors: Merz Reiner , Schneider Friedh.
Published: August 2018

Centrifugal elutriation was applied to separate into the cell compartments asynchronous Ehrlich ascites cells grown under different culture conditions. The cytokinetic properties of the recultivated fractions were studied by flow cytometry. The present experiments prove that G 1- cohorts grown 12 h under exclusion of oxygen accumulate in the late G 1-compartment. The cyto­kinetic properties of these cells are not changed. In contrast the cytokinetic properties of anaerobically treated S-phase cells are changed; most of S-cells leave the cell cycle after they have attained the DNA content of G 2-cells and continue to synthesize DNA without preceeding division. Cells with a DNA content up to the fourfold of normal values are found.
Inverse Relationships between Ecdysteroid Titres and Total Body Metabolism in Insects
Authors: Sláma Karel
Published: August 2018

In larval and pupal stages of several insect species the changes in total body metabolism appear to be inversely proportional to the course of ecdysteroid titres. The largest peaks of ecdysteroid occur exactly at the time of the lowest metabolic rates. These relationships are consequences of the developmental programming; ecdysteroid has no direct antimetabolic action. The problem of ecdysteroid-metabolic interactions has been discussed in relation to possible homeostatic function of ecdysteroids in insect development.
Yeast Aminopeptidase II: Rapid Purification Using Affinity Chromatography of the Periplasmic Enzyme
Authors: Knüver Joseph , Röhm Klaus-Heinrich
Published: August 2018

Periplasmic aminopeptidase II of yeast was isolated from protoplast supernatants by ammonium sulfate precipita­tion, DEAE-Sephacel chromatography and affinity chromatography on immobilized bestatin. This isolation method is more rapid than conventional procedures and, in addition, avoids contact of the enzyme with yeast protein-ases. Thus the preparation obtained is likely to represent the native periplasmic from of aminopeptidase II.
Stadienspezifische Thylakoiddifferenzierung der Endocyanelle Cyanocyta korschikoffiana in der symbiontischen Assoziation mit Cyanophora paradoxa / Growth Specific Thylakoid Differentiation of the Endocyanelle Cyanocyta korschikoffiana in the Symbiotic Association with Cyanophora paradoxa
Authors: Brandt Peter , Marten Sabine , Müller Birgit , Wießner Wolfgang
Published: August 2018

The thylakoid differentiation in the endosymbiotic cyanelle Cyanocyta korschikoffiana depends on the developmental stage of the whole symbiotic association Cyanophora-Cyanocyta. During culturing under permanent light the intrinsic or extrinsic location and the amount of the chlorophyll-protein complexes and of the phycobilines in the thylakoids change markedly. During this modification of the thylakoids the reaction centers of phytosystem I and II are more and more protected by other proteins. Moreover the amount of phycobilisomes increases in relation to the amount of the chlorophyll-protein complexes. The energy transfer becomes more and more efficient. All these aspects show the typical behaviour of a mass culture of a free-living blue-green alga and imply that Cyanocyta korschikoffiana is a symbiotic cyanelle much more than a chloroplast-like organelle.
Immobilization of Yeast Cells by Radiation-Induced Polymerization
Authors: Fujimura T. , Kaetsu I.
Published: August 2018

Radiation-induced polymerization method was applied to the immobilization of yeast cells. The effects of irradiation, cooling and monomer, which are neccessary for polymerization, were recovered completely by subsequent aerobical incubation of yest cells. The ethanol productive in immobilized yeast cells increased with the increase of aerobical incubation period. The growth of yeast cells in immobilized yeast cells was indicated. The maximum ethanol productivity in immobilized yeast cell system was around three times as much as that in free yeast cell system.
Enzymatische Hydroxylierung von Ruthenocen und Osmocen durch Leber-Mikrosomen / Enzymatic Hydroxylation of Ruthenocen and Osmocene
Authors: Schneider Michael , Wenzel Martin , Schachschneider Gerd
Published: August 2018

In buffer solution (pH 7,4) ruthenocene and osmocene are far more stable than ferrocene. The metallocenes ruthenocene and osmocene are metabolized by microsomes of mouse liver in the presence of NADPH and O2. The KM-values are similar for both metallocenes, the rate of metabolism is higher for osmocene that for ruthenocene.
Neutral Red Fluorescence of Chromatin: Specificity and Binding Mechanism
Authors: Espelosin Roberto H. , Stockert Juan C.
Published: August 2018

Neutral Red, Chromatin Fluorescence, Nucleic Acid Cytochemistry, Intercalative Binding to DNA After treatment with neutral red at low concentrations (10-6, 10-5 m), the chromatin o f chicken erythrocytes shows an intensive red fluorescence, which is reduced or prac­ tically abolished when nuclei become stained by using the dye at concentrations higher than 10~* M. Both the fluores­ cence and staining reactions are dependent on the DNA content of chromatin. Neutral red fluorescence o f nuclei increases considerably after treatment with inorganic cations (Al3+, Ba2+), while previous treatments with meth­ ylene blue reduce the fluorescence intensity. The possi­ bility that chromatin fluorescence depends on the inter­ calative binding of neutral red is suggested.
Changes of C-Phycocyanin in Synechococcus 6301 in Relation to Growth on various Sulfur Compounds Materials and Methods
Authors: Schmidt Ahlert , Erdle Ingrid , Köst Hans-Peter
Published: August 2018

The cyanobacterium Synechococcus 6301 is able to use a limited number of sulfur compounds as the only source of sulfur supply such as sulfate, thiosulfate, thioacetic acid, mercaptoacetic acid, thioacetamide, ʟ-cysteine and glutathione. Compounds containg thioether linkages such as methionin or S-methylcysteine and all compounds investigated so far containing sulfonic acid structures do not support growth. Growth inhibiton was observed by addition of aminomethane- sulfonic acid or cysteamine.

When non-growth sustaining sulfur compounds are added as sulfur source, the C-phycocyanin content of the Synechococcus cultures decreased drastically, causing a shift in color from blue- green to yellow-green. An analysis reveals the degradation of C-phycocyanin whereas chlorophyll formation still proceeds to a certain degree in growing sulfur-starved cells. Supplementation of a suitable sulfur source induces a period of intense and preferential C-phycocyanin synthesis prior to resumption of normal growth.
The Tautomerism of Cytosine and Hydroxycytosine. A Quantum-Mechanical Study
Authors: Kwiatkowski Józef S. , Lesyng Bogdan , Palmer Michael H. , Saenger Wolfram
Published: August 2018

Semi-empirical studies by the MNDO and MINDO-3 methods together with ab initio studies by the Hartree Fock method, have been performed on the tautomers of cytosine (C) and hydroxycytosine (HC), in each case with full optimisation of the molecular skeleton. The results are in agreement with recent solution studies of these systems, and show that the amino form of C and the oxime form of HC are the lowest energy tautomers. Thus the property is one of the ring system rather than environment.

Various conformers of the imino tautomer of 5-methyl-N(4)-hydroxycytosine were studied by MINDO/3 and PCILO calculations; although only partial geometry optimisation was performed, it seems unlikely that the molecule can be a complementary base to adenine in the Watson-Crick sense.`
The Reversibility of the Vitamin C Redox System: Electrochemical Reasons and Biological Aspects
Authors: Sapper Helmut , Institut für Biophysik der Justus-Liebig-Universität Gießen, Sa-Ouk , Paul Hans-Helmut , Lohmann Wolfgang
Published: August 2018

The biological efficacy of vitamin C depends on its redox abilities as given by the relations between ascorbic acid, semidehydroascorbic acid, and dehydroascorbic acid. It is shown by means of proton magnetic resonance spectroscopy that the enzymatic (by ascorbate oxidase) as well as non-enzymatic (by iodine) oxidation of ascorbic acid is, in principle, reversible despite the hydration and structural changes during the formation of dehydroascorbic acid. The strong redox activity of semidehydroascorbic acid which results in a fast disproportionation to ascorbic acid and dehydroascorbic acid is inferred from an inversion of the electrochemical potentials of the vitamin C redox system. The capacity of this is maintained by a fast reduction of dehydro­ ascorbic acid e.g. by reduced glutathione, preventing its delactonization and further degradation.
Differentiation in Volvox carteri: Study of Pattern Variation of Reproductive Cells
Authors: Gilles Rainer , Jaenicke Lothar
Published: August 2018

Asexual spheroids of the multicellular green alga Volvox are composed of two types o f cells: non-flagellated reproductive gonidia and Chlamydomonas-like flagellated somatic cells. They are committed by a differentiating cleavage during embryogenesis. The gonidia of the adult spheroids form a symmetrical pattern consisting of four layers of four gonidia each; their position is established already in the embryos by the gonidial initials. Whereas, generally, the 16-gonidia pattern is assumed to be the basic one, most o f the spheroids have fewer gonidia (down to 8). The nine possible gonidial patterns (8 to 16 gonidia) are described and correlated to the gonidial stem cells which have been differentiated. Defects in gonidial pattern are of particular interest, since any model of differentiation has to explain not only the basic pattern formed, but also its systematic variations. Our study shows that the pattern reduction is by no means random, but governed by an intrinsic mechanism which shifts the first unequal cleavage from the 32-celled stage to the 16-celled stage. All the patterns formed can be deduced from cleavage pathways involving non-synchronous differentiation of the stem cells. Thus, pattern formation can be correlated to timing and spacing signals regulating events during embryogenesis.
Biological Activities of Sesquiterpene Lactones from Helianthus annuus: Antimicrobial and Cytotoxic Properties; Influence on DNA, RNA, and Protein Synthesis
Authors: Spring O. , Kupka J. , Maier B. , Hager A.
Published: August 2018

Sesquiterpene lactones, produced in light and capable of inhibiting auxin-induced elongation growth of coleoptile and hypocotyl segments, were isolated from young leaves of Helianthus annuus (Spring and Hager, Planta in press, 1982).

These compounds have an antibiotic effect on gram-negative and gram-positive bacteria as well as on some fungi. The minimal inhibiting concentration (MIC) of compound II (15-hydroxy-3- dehydrodesoxyfruticin. Fig. 1), for example, is 15μg/ml for Bacillus brevis, and 95 μg/ml for the fungus Eremothecium ashbyi.

In addition, cytotoxic effects on mouse myeloma cells (NS-1) were also shown. Compound II causes a 50% inhibition of cell proliferation (ED50) at a concentration of 170nᴍ, compound I (niveusin C, Fig. 1) at 220 nᴍ. The LD50-values were 0.15 μg ll/ml and 1.24 μg I/ml, respectively.

By measuring 14C-labelled thymidine, uridine and leucine incorporation into murine cells of the ascitic form of Ehrlich carcinoma (EAC) it could be shown that compounds I and II inhibit DNA and RNA synthesis, but do not affect the translation processes involved in protein synthesis.

Furthermore, it could be shown that the exocyclic methylene group in the molecules of I and II plays an important role in triggering the described inhibitory effects.
Some Observations on the Saponin Accumulation in Oat Seedlings and on the Transformation of the Avenacosides to the Antibiotic 26-Desgluco-avenacosides
Authors: Laudenbach Ute , Kesselmeier Jürgen
Published: August 2018

The accumulation of the steroidal saponins avenacoside A and B in oat was investigated in green and etiolated seedlings and was found to be strictly bound to the growth of the seedlings. No significant differences were detected between green and etiolated seedlings, showing that there is no relation between saponin accumulation and plastid development. As the role of the oat saponins has to be seen as a protective device against fungi and bacteria, the transformation of the inactive avenacosides to their corresponding antibiotic 26-desgluco-avenacosides was tested in dependence of pH and temperature. During disruption of leaves, transformation occurs almost completely over a wide pH-range (pH 4 -pH 10); the degree of transformation exhibits no distinct temperature optimum but a drastic decrease at 70 °C.
Statistical Description of Isotope Exchange Processes: A Multisite Model for the 18O Exchange
Authors: Rösch Paul
Published: August 2018

An analytical procedure has been developed for the determination of isotope exchange processes as exemplified by the 18O exchange catalysed by enzyme-nucleotide complexes. The model is able to handle more than one type of active site per reaction solution and is also able to distinguish between different types of inequivalence of the oxygens of enzyme bound Pi. Use of transition matrix formalism and basic statistical considerations lead directly to the simple model. A data refinement procedure is introduced and model calculations are shown.
Fluorescence Studies on N-(3-Pyrene)Maleinimide-Labeled Sarcoplasmic Reticulum ATPase in Native and Solubilized Membranes
Authors: Lüdi Hans , Hasselbach Wilhelm
Published: August 2018

Fluorescence polarization and formation of excimers were studied in N-(3-pyrene)maleinimide-labeled sarcoplasmic reticulum vesicles.

1. The polarization of pyrenemaleinimide labeled vesicles does not change with temperature and shows a pronounced decrease at labeling concentrations larger than 1 mol pyrenemaleinimide per 10 mol ATPase.

2. Solubilization of the membrane with myristoylglycerophosphocholine renders the polarization temperature dependent, but does not affect the concentration dependent depolarization observed in native vesicles.

3. The polarization of labeled vesicles is much smaller than to be expected from the temperature independent polarization indicating that the pyrenemaleinimide polarization did not monitor the rotation of the entire ATPase. Thus segmental motion occurs.

4. Pyrene excimers are observed at label concentrations larger than 1 mol label per 2.5 mol ATPase.

5. The amount of excimers was critically dependent on added detergents. From the fact that non-solubilizing amounts of myristoylglycerophosphocholine strongly reduced the amount of pyrene excimers it is concluded that in the native sarcoplasmic reticulum vesicles at least two ATPase molecules must be in close contact.
Diterpenes of Cheilanthes argentea, a Fern from Asia
Authors: Wollenweber Eckhard , Rüedi Peter , Seigler David S.
Published: August 2018

The major components o f the white exudate or farina from the abaxial side of fronds of the fern Cheilanthes argentea are the diterpenoid acids ent-8(17),E-13-labdadien-15-oic acid and its 3 R-hydroxy derivative. This is the first report of the first o f these compounds as a natural product. Both are highly crystalline. Plants from the Asian mainland and Japan contain mostly the first compound whereas plants from Taiwan contain mostly the 3 R-hydroxy derivative. Thus, there are at least two distinct chemical races of the species Cheilanthes argentea.
Isolation and Synthesis of a Hemoregulatory Peptide
Authors: Paukovits Walter R. , Laerum Ole D.
Published: August 2018

A peptide was isolated in pure form from human leukocytes which strongly inhibits the proliferation of immature meyloid cells in vitro (committed stem cells). Structural investigations yielded pGlu-Asp or Glu-Asp or Glu-Cys-Lys-OH as the probable sequence of this peptide. The Glu2,Asp3-analog, prepared synthetically, displayed similar activities and when applied in vivo showed effects on the hemopoietic system ranging from an inhibition of pluripotent and committed stem cells to variations in the bone marrow proliferation and alterations in peripheral blood counts.
Isolierung von PS II-Partikeln mit in vivo Eigenschaften aus Euglena gracilis, Stamm Z / Isolation of PS II-Particels with in vivo Characteristics from Euglena gracilis, Stamm Z
Authors: Schuler F. , Brandt P. , Wießner W.
Published: August 2018

An improved method for isolation of (photosystem II)-particles from Euglena gracilis, strain Z was established. PS II-particles isolated by ultrasonic treatment and following differential centrifugation show fluorescence emission and absorption spectra identical with in vivo properties of Euglena gracilis. These PS II-particles have only PS II-activity and contain CP a, the typical chlorophyll-protein-complex of PS II. No contamination of PS I-components are detectable.
Volatile Compounds from Cephalic Secretions of Females in two Cleptoparasite Bee Genera, Epeolus (Hym., Anthophoridae) and Coelioxys (Hym., Megachilidae)
Authors: Tengö J. , Bergström G. , Borg-Karlson A.-K. , Groth I. , Francke W.
Published: August 2018

Volatile cephalic secretions from females of four cleptoparasitic bee species, Epeolus cruciger (Pz.), E. variegatus, (L.) (Anthophoridae) and Coelioxys (Coelioxys) quadridentata (L.), C. (Schizocoelioxys) mandibularis Nyl. (Megachilidae) were analysed by combined gas chromatography/mass spectroscopy. There are considerable similarities between the two species within each genus, and also some qualitative correspondences between the two genera. The Epeolus species contain spiroacetals, 2-alkanols and pyrazines while the Coelioxys species contain spiroacetals, 3-alkanols and 3-ketones along with unsaturated alcohols. Two of the spiroacetals are first found in nature.