bluuebunny/crossref_metadata_2025_split huggingface dataset:
13C NMR Investigations on the Stacking of 5′ -AMP with Tryptamine
Authors: Wray V. , Wagner K. G. 
Published: August 2018

Abstract
Stacking, Relaxation Time, Tryptamine, 5′-Adenosine Monophosphate Complex formation between 5′-adenosine monophosphate (5′-AMP) and tryptamine was in­ vestigated by measuring 13C chemical shifts and spin-lattice relaxation times. The chemical shift changes observed were attributed to ring current effects originating in the stacking of the two respective aromatic moieties and to puckering changes of the AMP ribose. Differences in the magnitude of the shifts of the aromatic carbons were related to the geometry of the complex and compared with those found for AMP selfassociation. Upon complex formation the relaxation times of especially the tryptamine indole carbons were greatly reduced, this was explained by an in­ crease in the particle size. Small changes found for the AMP carbons in solutions without tryptamine result from AMP selfassociation. Deviations from isotropic motion observed for the non-aromatic moieties are discussed.
Isolierung und Charakterisierung eines membrangebundenen Pyruvatdehydrogenase-Komplexes aus dem phototrophen Bakterium Rhodospirillum rubrum /Isolation and Characterization of a Membrane-Bound Pyruvate Dehydrogenase Complex from the Phototrophic Bacterium Rhodospirillum rubrum
Authors: Lüderitz Rosemarie , Klemme Jobst-Heinrich 
Published: August 2018

Abstract
The pyruvate dehydrogenase complex from the photosynthetic bacterium Rhododospirillum rubrum was associated with the membrane fraction both in heterotrophically and photosynthetically grown cells. The complex was separated from the membranes and partially purified by precipitation with MgSO4 and gelfiltration through Sepharose 4B. The purified complex had a specific activity of 1.5 - 2 μmol/min-mg protein and contained the following partial activities: pyruvate dehydrogenase (EC 1.2.4.1), dihydrolipoamide transacetylase (EC 2.3.1.12) and dihydrolipoamide dehydrogenase (EC 1.6.4.3). Contrary to other bacterial pyruvate dehydrogenase complexes, the enzyme complex from R . rubrum revealed no cooperativity between pyruvate binding sites. The kinetic constants [Km) for the overall reaction were (in mм) : 0.14 (pyruvate), 0.07 (NAD) and 0.025 (coenzyme A). The Km for thiamine pyrophosphate was dependent on the nature and the concentration of the divalent metal ion (Mn or Mg) present in the reaction mixture, the values ranging from 0.5 to 3 μm . NADH was a potent inhibitor (Ki = 5 μm) of the enzyme complex and the dihydrolipo­ amide dehydrogenase. The inhibition was competitive with respect to NAD. In addition to its rapid inhibitory effect, NADH also inactivated the enzyme. Cysteine partially protected the enzyme complex against NADH-inactivation. Acetyl-coenzyme A also inhibited the overall reaction (Ki = 40 μм) . The inhibition was dependent on the concentration of coenzyme A, but independent of the concentration of pyruvate. Sugar phosphates, phosphoenolpyruvate, citric acid cycle intermediates and nucleosidephosphates (1 mм) had no pronounced effect on the overall reaction.
A Fluorescence Method for Measuring the Retention of Coupling Factor (CF1) in Reconstitution Experiments of Photophosphorylation
Authors: Harnischfeger Götz , Schopf Reinhard 
Published: August 2018

Abstract
The recombination of chloroplast coupling factor 1 (CF1) and thylakoid membranes in reconsti­ tution experiments was studied through the fluorescence of paired labels covalently bound to NH2-groups. It was found that maximum recombination is achieved at a ratio of 1.5 -3,μg CF1 /μg chlorophyll. The addition of chloroplast lipids to the medium enhances the incorporation of CF1 into the membranes.
The rates of ATP formation of the regenerated but labeled system are decreased to 50% of those found in unlabeled control experiments. This is discussed in context with the previous observation, that labeling of CF1 at similar concentrations inhibits the ATPase activity of the isolated protein completely.
The possible use of double labeling in the study of the physical aspects of the reconstitution of the photophosphorylating system is discussed.
Evolution of the Transfer RNA Molecule Evolution of the Transfer RNA Molecule
Authors: Erhan Semih , Greller Larry D. , Rasco Barbara 
Published: August 2018

Abstract
Base sequences of many transfer RNA (tRNA) species obtained from different sources contain homologous regions. These homologies, which are 6 to 20 nucleotides long, occur both within the same tRNA molecule and between many different tRNA molecules repeatedly. Since it is very unlikely an 80 or so nucleotide long tRNA molecule could have been formed at once, under primordial conditions, we propose that the homologous oligonucleotides found within the tRNA molecules to-day represent the earliest adapter from which tRNA molecules have evolved.
Chromosomale Strukture von Pseudomona testosteroni IV. Wirkung von Testosteron auf die RNA-Synthese / Chromosomal Structures of Pseudomonas testosteroni IV. Effect of Testosterone on RNA-Synthesis
Authors: Reimer G. , Drahovsky D. 
Published: August 2018

Abstract
Testosterone degrading enzymes are synthesized de novo by bacterium P. testosteroni to utilize testosterone-like steroids as the only source of carbon. RNA-synthesis of the whole lysate of testosterone-induced bacteria was found to be 15% reduced compared to the control, suggesting a cytoplasmatic factor which modulates chromatin associated RNA-polymerase activity.
Röntgenstrukturanalyse von Mezerein aus Daphne mezereum L. / X-Ray Structure Analysis of Mezerein from Daphne mezereum L
Authors: Lotter H. , Jones A. , Sturm M. 
Published: August 2018

Abstract
Mezerein, Daphne mezereum, X-Ray Structure, Antileukemic Principle The X-ray structure of Mezerein from Daphne mezereum L. was determined by aid of direct methods. Comparison with Phorbol and Daphnetoxin led to the absolute configuration. A tentative mechanism for the antileukemic activity is proposed.
Structure and Anticholinesterase Activity of Series of Ethyl Substituted Phenyl Methylphosphonates
Authors: Relimpio Angel M. 
Published: August 2018

Abstract
Thirty derivates from substituted-phenyl-ethyl methylphosphonates have been synthesized and their inhibiting power of acetyl-cholinesterase have been examined in vitro and in vivo. The correlation between inhibition of the enzyme and electrophylic power of the substituent of the phenyl group was excellent, but when this group contains two substituents, steric factors appear to operate. The activity of these compounds has been demonstrated to be higher than their phosphate analogs.
O n the Mechanism of Inactivation and ATP-Dependent Reactivation of Rat Liver Tyrosine Aminotransferase
Authors: Hamm Hans-Heinrich , Seubert Werner 
Published: August 2018

Abstract
The mechanism of in vitro inactivation and ATP-dependent rapid reactivation of rat liver tyrosine aminotransferase by a membrane-bound system from rat liver and kidney cortex and the nucleotide specificity of this process was investigated using partially purified tyrosine amino­ transferase as a substrate. Adenosine 5′-triphosphate (ATP) could be replaced by guanosine 5′-tri-phosphate (GTP), whereas inosine 5′-triphosphate (ITP) was less effective. During reactivation [γ-32P]A T P was incorporated into the enzyme and not excorporated by incubation of the labeled enzyme with excess non-radioative ATP. Inactivation of labeled tyrosine aminotransferase by a particulate fraction led to a decrease protein-bound radioactivity concomitant with an increase of [32P] orthophosphate. This points to a phosphorylation and dephosphorylation mechanism in the regulation of tyrosine aminotransferase activity.
Phosphorylation by Inorganic Phosphate of Sarcoplasmic Membranes
Authors: Rauch Bernhard , Chak Dorothee v. , Hasselbach Wilhelm 
Published: August 2018

Abstract
Phosphorylation, Dephosphorylation, Inorganic Phosphate, Sarcoplasmic Membranes The calcium transport protein of the sarcoplasmic reticulum accepts inorganic phosphate rapidly when phosphorylation is initiated either by the addition of phosphate or m agnesium ions to the calcium free protein. Phosphorylation proceeds much more slowly when it is initiated by the addition of the calcium chelator ethyleneglycol-bis (β-aminoethyl ether) -N ,N′-tetraacetic acid (EGTA) to the phosphate and magnesium containing assay. The time course of phosphorylation following immediately calcium removal is monophasic at all temperatures between 20° and 37 0|C. In contrast, phosphorylation of the calcium free enzyme becomes biphasic at temperatures above 25 °C. The biphasic time course does not only apply to net formation of phosphoprotein but also to its exchange with medium phosphate. On addition of calcium, the phosphoprotein decays in a biphasic process the time constants of which are much longer than those observed for phosphoprotein formation. The temperature dependence of the rate as well as of the extent of phosphoprotein formation indicate a discontinuity in the reactivity of the protein.
Growth Inhibition of Glucose-Grown Cariogenic and Other Streptococci by Saccharin in vitro
Authors: Linke Harald A. B. 
Published: August 2018

Abstract
Sodium saccharin in concentrations from 0.02 to 20.00 mg/ml inhibits the in vitro growth of glucose-grown cariogenic and other streptococci, and suppresses, esp. at the higher concentration range, the fermentative acid production of these microorganism s to acid levels much lower than the critical pH of 5.5. These observations indicate a possible caries antagonism by saccharin.
Development of Phage Populations in a Bacterial Culture: a Mathematical Model
Authors: Grossi G. F. , Cesareni G. , Liello F. 
Published: August 2018

Abstract
A mathematical model for the interaction kinetic in phage-bacterium culture is proposed. An appropriate analytical relationship between phage and bacterial concentrations has been derived. Characteristic kinetic constants have been obtained by com paring the experimental growth curves with computer-simulation analysis. The model allows also to evaluate the phage-yield as a function of the initial concentrations.
Some Properties of Plastidic Cytochrome b-563
Authors: Lach H. J. , Böger P. 
Published: August 2018

Abstract
Plastidic Cytochrome b-563 Cytochrome b-563 from spinach chloroplasts was isolated in a homogeneous and enzymatically active form. It has a low, but variable lipid content and a molecular weight of about 18,000 daltons.
Electrophysiological Properties of R7 and R8 in Dipteran Retina
Authors: Hardie R. C. 
Published: August 2018

Abstract
Intracellular recording and dye injection have directly demonstrated the absolute and spectral sensitivities of R7 and R8 in the eye of Calliphora. R8 has major peak of sensitivity at 547 nm with less than half the bandwidth of a theoretical rhodopsin, and a subsidiary peak at 358 nm. R7 is confirmed as being an ultraviolet receptor. Both have absolute sensitivities similar to those of R 1 -6. These results are inconsistent with the scotopic (R1-6), photopic (R7 and R8) theory of fly vision.
Effect of Cortisone on Aspartate and Alanine Aminotransferases in a Desert Lizard
Authors: Aziz Shaharuddin , Hasnain S. N. , Zain Barbara K. 
Published: August 2018

Abstract
1. Liver and serum aspartate aminotransferase (GOT) and alanine aminotransferase (GPT) activities were measured in a hibernating desert lizard, Uromastix hardwickii. The levels of both enzymes were found to be lower in hibernation than during the active period, particularly in the liver.
2. After intramuscular injection of 2 mg of cortisone acetate there was a rapid rise in the levels of these enzymes with a peak of 18 hours (GOT) and 12 hours (G P T).
3. The response of both enzymes to cortisone was much greater during the active period than during hibernation.
4. GOT showed a much more rapid and greater response to cortisone than GPT. This is in contrast to the response of rat liver where GPT is more responsive to this hormone.
5. These studies indicate that the transferase enzymes of this lizard differ from those of the rat in their sensitivity and time of response to cortisone.
Stoichiometry of H2 Production by an in vitro Chloroplast, Ferredoxin, Hydrogenase Reconstituted System
Authors: Packer Lester , Cullingford William 
Published: August 2018

Abstract
Studies of the rate and efficiency of H2 production by a reconstituted system composed of washed chloroplasts, ferredoxin, and hydrogenase reveal th at a significant proportion of the low potential electrons are leaked to H2O2 production via auto-oxidation of ferredoxin even in the presence of an oxygen trap (glucose and glucose oxidase). U nder optimum conditions of ferredoxin concentration the leak can be m inimized such th at H2 production is about 70% of the ferricyanide Hill reaction rate.
Modellreaktionen zur kooperativen Amid/SH- Katalyse der Esterhydrolyse / Model Reactions of the Concerted Amide-SH Catalysis of Ester Hydrolysis
Authors: Petz Dorothee , Schneider Friedhelm , Löffler Hans-Georg 
Published: August 2018

Abstract
An enhancement of the rate of hydrolysis of certain methyl esters by cooperative effects of neighbouring amide and SH groups is demonstrated. The rate of hydroxyl ion catalyzed hydrolysis of the most reactive ester exceeds the rate of saponification of simple aliphatic esters by a factor of about 103. A mechanism of the saponification reactions involving intermediate cyclic imide formation is proposed.
The Inhibition of Photosynthetic Electron Flow in Chloroplasts by the Dinitrophenylether of Bromo-or Iodo-nitrothymol
Authors: Trebst A. , Wietoska H. , Draber W. , Knops H. J. 
Published: August 2018

Abstract
The O -dinitrophenyl derivatives of 2 -bromo-and 2-iodo-4-nitrothymol are inhibitors of photo­ synthetic electron flow from water to NADP or methylviologen, yielding 50% inhibition at 0.5 μм. Photoreductions by either photosystem I or photosystem II alone are not inhibited. The inhibition site is bypassed by TM PD. The inhibition pattern identical to the one of dibromothymoquinone. It is reduction of plastoquinone.
Studies Supporting the Concept of Glyoxyperoxisomes as Intermediary Organelles in Transformation of Glyoxysomes into Peroxisomes
Authors: Koller Wolfram , Kindi Helmut 
Published: August 2018

Abstract
Intermediary forms of microbodies, glyoxyperoxisomes, are most likely synthesized at the stage of replacement of glyoxysomes by peroxisomes during the greening of fatstoring cells of cucumber cotyledons. This hypothesis is supported by three lines of results: 1. The levels of both glycollate oxidase and malate synthase are increased in the m icrobody fractions upon illumination of cotyleons. 2. Both peroxisomal and glyoxysomal marker enzymes are localized in organelles which exhibit the same buoyant densities. 3. De novo synthesis of malate synthase takes place even when irradiation already leads to a drastic increase of glycollate oxidase. The amount of malate synthase synthesized is almost identical in the light-induced system and in the dark control.
Cesium Determination in Physiological Fluids and Tissues by Field Desorption Mass Spectrometry≠
Authors: Schulten H.-R. , Ziskoven R. , Lehmann W. D. 
Published: August 2018

Abstract
Quantitative ultratrace analysis (10 nmol to 10 /cmol/1) of cesium in biological samples such as human body fluids and animal tissues is performed without any prior purification or concentration steps. The normal level of cesium ions in heart cells was determined. After poisoning these cells with high concentrations of the alkali cation much higher levels were found inside the cells then had been suggested previously. It is demonstrated that field desorption mass spectrometry is a unique tool for the qualitative and quantitative investigations of metal cations in biological material.
Determination of the Electron Density Profile of the Nerve Myelin Membrane in Different States Taking Paracrystalline Lattice Distortions into Account
Authors: Gbordzoe M. K. , Kreutz W. 
Published: August 2018

Recent investigations point to the presence of paracrystalline lattice disorder in the nerve myelin in the swollen, fixed and to some extent also in the native state. This leads to the distortion of the Q-function of the membrane stack and the Q0-function of the unit cell, which can be ex­perimentally isolated through swelling.
Representing the distance statistics between neighbouring membranes and the electron density distribution of the single membrane with Gaussian functions, the Q-function can be expressed analytically as a convolution polynomial of the electron density, its mirror image and the distance statistics functions. Fitting this model (^-function to the experimental Q-function obtained by the inverse Fourier transformation of the scattered intensity, one can determine the optimal parameters of the electron density distribution and the distance statistics functions. The elimination of the distance fluctuations between neighbouring membranes permits the calculation of the undistorted Q-function or the Q0-function. The Fourier Analytical Deconvolution of the undistorted Q0-function enables a unique determination of the double membrane profile, thus a unique phase determination.
Derivate des Benzo[1.3]dioxols, 431 Über Benzo [1.3] dioxolcarbonsäuren / Derivatives of 1,3-Benzodioxoles, 43 1,3-Benzodioxolecarboxylic Acids
Authors: Daliacker Franz , Mues Volker , Kim In-O 
Published: August 2018

Abstract
We describe the possibilities of formation and preparation of the “natural” 1,3-benzodioxolecarboxylic acids 1, 2, 4, 6 b, and 7, already mentioned in literature. Myristic acid (3e) was prepared in good yield from 3-methoxy-4,5-dihydroxy-benzoic acid ester (3c) , which could be easily made from 3-methoxy-2,3-carbonyldioxy-benzoic acid methylester (3b). Myristicic acid methylester (3d) could be subjected to methylation and hydrolysis leading to 3e without any difficulties.
4.6-dimethoxy-1,3-benzodioxole-5-carboxylic acid (5b) was prepared in good yields by oxidation of 4,6-dimethoxy-1,3-benzodioxole-5-aldehyde (5a).
5.7-dimethoxy-1,3-benzodioxole-carboxylic acid (13f), one of the “unnatural” 1,3-benzodioxolecarboxylic acids, derivatives of o-ipiperonylic acid (8), was prepared from 5-amino-7-methoxy-1,3- benzodioxole-4carboxylic acid methyl ester (13b) by diazotisation, elimination of nitrogen, methylation, and hydrolysis. A comparison of our measured pkA-values showed the strongest acidity belonging to 5,6-dimethoxy-1,3-benzodioxole-4-carbocylic acid (11).
Partial Structure of Papiliochrome, the Yellow Wing Pigment of the Papilionid Butterflies
Authors: Rembold Heinz , Rascher Jakob , Eder Jörg , Umebachi Yoshishige 
Published: August 2018

Abstract
Papiliochrome II, one of the yellow wing pigments of the Papilionid butterfly, Papilio xuthus, can be split into ʟ-kynurenine and a catecholamine derivative, SN-1, by 10-3 n HCI. The latter is hydrolyzed by ɴ HCI into β-alanine and noradrenaline. The structure of SN-1 has been elucidated as N-(β-alanyl)-ʟ-noradrenaline by NMR and MS data as well as by synthesis. Preparation of the N-hydroxysuccinimide ester of benzyloxycarbonyl-β-alanine, its condensation with ʟ-noradrenaline to the corresponding benzyloxycarbonyl protected SN-1 and of N- (β-alanyl)-ʟ-noradrenaline by hydrogenolysis of the protecting group are described.
Is Oxygen Consumption of Surviving Tissues Determined by the Oxygen Tension of the Suspension Medium?
Authors: Pichotka Josef Peter , Schmidt Hans Josef 
Published: August 2018

Abstract
Oxygen tension in the suspension medium and oxygen uptake of the isolated diaphragm of the mouse have been determined simultaneously with systematic variation of shaking frequency and oxygen concentration of the gas phase. Oxygen tension in the suspension medium readies its final value during the usual equilibration period of 10 minutes and remains constant for the whole measuring period. Each combination of shaking frequency and oxygen concentration of the gas phase results in a reproducible value of oxygen tension in the medium. Equal oxygen tension in the fluid phase can be attained by different combinations of shaking frequency and oxygen concentration of the gas phase. Oxygen uptake at the same oxygen tension of the suspension medium can be very different; it is the higher the higher the shaking rate in the combination. On the other hand the same oxygen consumption of the tissue samples can be observed with highly different oxygen tensions in the medium. It must be concluded from the data in this paper, that the influence of shaking rate per se on the oxygen uptake of isolated tissue can be of the same order as the influence of oxygen tension.
Spatial Structures in a Model Substrate-Inhibition Reaction Diffusion System
Authors: Mimura Masayasu , Murray J. D. 
Published: August 2018

Abstract
An important new model universal oscillator proposed by Seelig which depends on substrate inhibition is considered. In a finite spatial domain with zero flux boundary conditions and in which the substrates can diffuse it is shown that diffusion-driven instability is possible and can result in finite amplitude spatial structures. Illustrative numerical results are presented which exhibit this behaviour.
Zur Frage biogener Anreicherungen von Vanadium und Nickel in Pflanzen des Karbonzeitalters / The Question of Biogenous Enrichments of Vanadium and Nickel in Plants of the Carbon Age
Authors: Meisch Hans-Ulrich , Reinle Wolfgang , Richter Bernd-Arwed 
Published: August 2018

Abstract
Original carbonaceous material of fossile carbon plants from the divisions of the Equisetophyta (Calamariaceae), Lycophyta (Lepidodendraceae, Sigillariaceae), Filicophyta (Filicatae), and Spermatophyta (Pteridospermatae, Cordaitidae) was analyzed by atomic absorption spectroscopy on its content of the trace metals vanadium and nickel. The average V-content was found to be 10 to 100 fold higher than that of the neighbouring coal beds or that of the embedding materials, while the Ni-concentrations were found to be almost in the same range. The highest contents of V and Ni were found in the Calamariaceae and in the Pteridospermatae. The V-and Ni-contents of the fossile carbon plants are compared to those of related recent plant genera (clubmosses, horse­ tails, ferns), which were analyzed by 46 representative samples. A possible biogenous enrichment of V and Ni in plants of the carbon age is discussed.
The Role of Ubiquinone-10 in Cyclic Electron Transport in Rhodopsendomonas capsulata Ala pho+: Effects of Lyophilization and Extraction
Authors: Bowyer John R. , Baccarini-Melandri Assunta , Melandri B. Andrea , Crofts Antony R. 
Published: August 2018

Abstract
1. The effects of lyophilization and the extraction of ubiquinone-10 on the kinetics of electron transport in Rhodopseudomonas capsulata Ala pho+ have been investigated.
2. Lyophilization reduced the amount of ferrocytochrome c2 photo-oxidized on a microsecond time scale following a single excitation.
3. Lyophilization increased the reactivity of the electron transfer components with redox mediators, particularly N-methyl phenazonium methosulphate (PMS). At a concentration of 1 µᴍ , PMS accelerated reaction center re-reduction, ferricytochrome c2 re-reduction and ferrocytochrome b50 oxidation. The cytochrome c2 re-reduction stimulated by PMS was antimycin A insensitive but the cytochrome b50 oxidation was partially antim ycin sensitive.
4. Removal of 25- 30 molecules of ubiquinone 10 per reaction center removed a secondary acceptor pool, had very little effect on the kinetics of ferricytochrome b50 reduction and ferricyto­ chrome c2 re-reduction, but markedly inhibited ferrocytochrome b50 oxidation. Ubiquinone extraction also caused an increased stimulation of ferrocytochrome b50 oxidation by PMS.
5. The involvement of tightly bound ubiquinone in cytochrome b reduction and in the cytochrome b-c2 oxido-reductase, and the role of semiquinone species is discussed.