bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nucleoside Triphosphate Levels in Streptomyces hydrogenans during Growth and Induction of 20β-Hydroxysteroid Dehydrogenase
Authors: Betz Joachim , Träger Lothar 
Published: August 2018

Abstract
Levels of the purine nucleoside triphosphates are de­ creasing towards the end of log phase growth of Streptomyces hydrogenans. Induction of 20β-hydroxysteroid dehy-drogenase by addition of 11β,21-dihydroxy-4,17 (20) -pregna-dien-3-one to the growth medium leads to a pronounced drop in purine nucleoside triphosphate levels with is irreversible in contrast to the initial loss and later accumulation of RNA.
Induced Isoflavonoids from Fungus-Infected Stems of Pigeon Pea ( Cajanus cajan)
Authors: Ingham John L. 
Published: August 2018

Abstract
Four antifungal isoflavones [7-hydroxy-4′-methoxy-(l) ; 5,7,4′-trihydroxy-(2) ; 5,7,2′,4′-tetra-hydroxy-(3) ; 5,2′,4′-trihydroxy-7-methoxy-(4) ] and one isoflavanone [ (5,2′-dihydroxy-7,4′-dimeth-oxy-(7)] have been isolated from the fungus-infected stems of Cajanus cajan . A sixth compound has been provisionally identified as 5,2′-dihydroxy-7,4′-dimethoxyisoflavone (5). The structure of 5,2′-dihydroxy-7,4′-dimethoxyisoflavanone (cajanol) was confirmed by synthesis from ferreirin ( 5,7,2′-trihydroxy 4′-methoxyisoflavanone).
The Crystal Structure of the Pyrimidine Analogue Calcium 5-Ethylidenehydroorotate · 1.5 Hydrate, a Photoproduct of Ethylorotate
Authors: Hingerty B , Kulikowska E , Saenger W , Shugar D 
Published: August 2018

Abstract
X-ray diffraction methods have been employed to establish the crystal structure of a new, unusual pyrimidine analogue, 5-ethylidenehydroorotate, obtained by a photochemical rearrangement of 5-ethylorotate. Crystals of the calcium salt of the title compound are monoclinic, space group Pc, cell constants a=14.631, 6 = 10.038, c = 19.168 Å,β = 137.7°, and contain four molecules, two cations and three water molecules per asymmetric unit. The structure was solved by direct methods and refined to R = 5.2% on the basis of 2653 diffractometer measured data. The four independent molecules represent two pairs of enantiomers with slightly differing conformations linked together by an intricate system of hydrogen bonding and Ca2+-coordination (pentagonal bipyrimidal). The structure of the compound in aqueous medium, as that in the crystal.
Präparative Isolierung des Protein III der menschlichen Erythrocytenmembran / Preparative Isolation of Protein III of the Human Erythrocyte Membrane
Authors: Schiechl H. 
Published: August 2018

Abstract
The paper describes a method for the large-scale isolation of protein III (protein E, major intrinsic protein) from the human erythrocyte membrane with little expenditure of time. By treat­ment of the erythrocyte ghosts with deluted HCl at pH 2.3 and 0 °C some membrane proteins can be extracted. From the remaining “rest”- membranes, whose major constituents, besides phospholipides, are protein PAS-1, other carbohydrate containing proteins and protein III, the latter can be separated in pure form by means of gel filtration. The paper reports on the amount, purity and possible structural modifications of the protein III obtained by this isolation method.
Effects of Phospholipids in the Action of Acetyl-CoA Carboxylase from Rat Liver
Authors: Heger H. Wolfgang , Peter Horst W. 
Published: August 2018

Abstract
Acetyl-CoA carboxylase (E.C. 6.4.1.2) was isolated from rat liver. The purified enzyme contains phospholipids with a rather large amount of phosphatidylinositol (26%). Incubation of the purified acetyl-CoA carboxylase with phospholipase A2 (E.C. 3.1.1.4) or with phospholipase D (E.C. 3.1.1.4) diminishes the phospholipid content by 70%, this treatment leading to a complete inactivation of the enzyme. After removal of the phospholipases, the lipid-depleted enzyme can be reactivated to a certain degree by incubation with a phospholipid extract from rat liver, with phosphatidylinositol alone, or with serum albumin.
Anomalous Base-Stacking of the N1-Oxide of AMP
Authors: Mantsch H. H. , Bârzu O. 
Published: August 2018

Abstract
The intermolecular association in aqueous solution of the N1-oxide nucleotide analog of adenosine-5′-monophosphate has been investigated by 1H-NMR spectroscopy over the concentration range 0.0006-0.6 ᴍ. The concentration profile of individual chemical shifts provides evidence for an unusual stacking pattern compared to that of the natural nucleotide AMP, involving only the imidazole moiety of the adenine base. The different stacking pattern of this nucleotide analog suggests that the exact stacking geometry of natural nucleotides interacting with nucleotide-depending enzymes, is achieved by adjusting to the geometry of the individual receptor molecule.
The Quaternary Structure of Yeast Aminopeptidase I
Authors: Metz G. , Marx Ruth , Rohm K.-H. 
Published: August 2018

Abstract
The smallest active form of aminopeptidase I (EC 3.4.11.1) from yeast has a molecular weight of 6.4 × 105. At neutral pH the active enzyme is in equilibrium with two inactive subfragments (Mr = 3.2 × 105 and 1.1 × 105) as well as with higher aggregates (Mr ≧ 1.2 × 106). All of these species may be dissociated to give a single type of subunits with a molecular weight of 5.3 × 104. It is concluded that the active enzyme is a dodecamer whereas the subfragments correspond to dimeric and hexameric forms.
A Chloroplast Photosystem 2 Reaction Resistant to Salicylaldoxime
Authors: Searle G. F. W. 
Published: August 2018

Abstract
Photoreduction of the artificial electron acceptor, cytochrome c, by isolated spinach chloroplasts in the absence of added catalyst has been found to be resistant to inhibition by 10 mᴍ salicyl­ aldoxime. This contrasts with the pronounced inhibition of the photoreduction of both 2,6-dichloro-phenolindophenol and ferricyanide over a range of electron flow rates, and indicates an inhibition on the acceptor side rather than on the donor side of photosystem 2 (PS2). All photoreductions were susceptible to inhibition by 3-(3′,4′-dichlorophenyl)-1, 1-dimethyl urea (DCMU). Salicyl­ aldoxime (1 -10 mᴍ) inhibited electron flow from PS2 to P700, and also altered the chlorophyll fluorescence induction of dark-adapted chloroplasts. Salicylaldoxime concentrations up to 5 mM did not change the initial fluorescence level, F0 , or the initial slope, (dF/dt)0 , but lowered the final steady state fluorescence level, Fm , and the value of p0 [p0= (Fm - F0)/Fm] ; an effect similar to that seen on 1 mᴍ ferricyanide addition, thus indicating an induced oxidation of the fluorescence quencher, Q. Both DCMU and orthophenanthroline, which block electron transport directly after Q, caused an increase in (dF/dt)0 , F0 and Fm but left p0 unchanged. This contrasted with the effect of salicylaldoxime.
It is proposed that salicylaldoxime inhibits electron transport from PS2 to photosystem 1, at a site which can probably be identified with the plastoquinone pool, by inducing a cyclic flow of electrons around PS2. Cytochrome c, under the conditions used, appears to be photoreduced at a site close to the secondary electron acceptor, R, of PS2.
Protein Synthesis and Amino Acid Pools in Irradiated Yeast Cells
Authors: Kiefer Jürgen , Laske Brigitte 
Published: August 2018

Abstract
Protein synthesis after UV-and X-irradiation was investigated in diploid yeast. The incorporation of radioactively labelled lysine and phenylalanine was measured 2.5 and 4 hours after exposure. By varying the specific activity the pool sizes could be estimated. At 2.5 hours there is some increase in pool sizes and a dose-dependent enhancement of protein synthesis. At 4 hours pools are again normal, but the increase of synthetic activity prevails.
Flavonoids and Related Compounds in Leaves of Pinaceae. II *. Cedrus atlantica c. v. Glauca
Authors: Niemann Gerard J. 
Published: August 2018

Abstract
Ten flavonol glycosides were isolated from leaves of Cedrus atlantica. Among the six aglycones the rarely occurring syringetin and laricitrin were found in addition to kaempferol, quercetin, isorhamnetin and myricetin. 3-Glyco-sylation with glucose and/or rutinose was the main pattern, whereas acylation with p-coumaric acid occurred for kaempferol-and isorhamnetin-3-glucoside.
γ-Radiolyses of DNA in Oxygenated Aqueous Solution. Structure of an Alkali-Labile Site
Authors: Dizdaroglu Miral , Schulte-Frohlinde Dietrich , Sonntag Clemens von 
Published: August 2018

Abstract
Erythritol-1-d1 has been isolated from γ-irradiated aqueous oxygenated solution of DNA after reduction with NaBD4 , alkali and phosphatase treatment. It is concluded that this product stems from a ᴅ-erythrose 2,4-diphosphate unit in the DNA which is formed via a sequence of reactions following H-abstraction at C-2′ by OH radicals..
Eine vereinfachte Methode zur Ableitung von Rezeptorpotentialen und Nervenim pulsen epidermaler Mechanorezeptoren von Insekten / A Simplified Method for Recording Receptorpoten- tials and Nervous Impulses of Insect Epidermal Mechanoreceptors
Authors: Erler Gernot , Thurm Ulrich 
Published: August 2018

Abstract
A simplified method is described for recording electrical potentials without injury from epidermal insect mechanoreceptors. For this purpose a stationary capillary-electrode is used with an anterior part made of polyethylene and filled with a hygroscopic electrolyte; its wide orifice allows the hair-shaft to keep contact when it is bent under the stimulus.
The Effect of Molecular Polarization on the Electrochromism of Carotenoids * II. Lutein-Chlorophyll Complexes: The Origin of the Field-Indicating Absorption-Change at 520 nm in the Membranes of Photosynthesis
Authors: Sewe Kai-Udo , Reich Roland 
Published: August 2018

Abstract
Electrochromic spectra of monolayers of carotenoids (lutein and β-carotene) in contact with monolayers of chlorophylls and of pheophytin a are measured in thin capacitors. A specific inter­ action of one of the OH-groups of lutein with the Mg-atom of chlorophyll is found. The formation of this oriented complex accounts for the fact that a part of the electrochromic absorption-change of lutein depends linearly on the electric field strength, whereas for lutein alone only a smaller, quadratic electrochromism is found. In the preparation with chlorophyll a, the maximum of this linear electrochromism is located at shorter wavelengths (512 nm) than in the preparation with chlorophyll b (517 nm).
The permanent field that has been postulated in photosynthetic membranes (to explain the linear dependence of the field-indicating absorption-changes of the carotenoids) may also be at­ tributed to such a complex formation with chlorophylls. Especially, the field-indicating absorption-change at 520 nm can now be attributed mainly to a lutein-chlorophyll b complex. The absorption-change at 520 nm, calculated according to this model from the present experiments in vitro, is of the same order of magnitude as observed in vivo. Furthermore, this model agrees with the hitherto unexplained observation that in chlorophyll-b-lacking mutants the absorption-change at 520 nm is smaller than in normal plants, and the maximum is located at shorter wavelengths. Besites, it is concluded that lutein is mainly located in the regions of photosystem II. The contributions of the other carotenoids (especially of neoxanthin) to the spectrum of the field-indicating absorption-changes are also discussed.
From the above model, some conclusions are drawn on the asymmetrical arrangement of the different pigments in the membrane of photosynthesis: The bulk chlorophyll molecules that serve as complex partners for the carotenoids should be located near to the inner surface of the thylakoid membrane, and the carotenoids attached to these chlorophylls should be located more to the out­ side. The phytol chain of a chlorophyll molecule should form an acute angle with the plane of the porphyrin ring.
Photosynthetic Hydrogen Evolution by Spinach Chloroplasts Coupled to a Clostridium Hydrogenase
Authors: Hoffmann D. , Thauer R. , Trebst A. 
Published: August 2018

Abstract
Photosystem I activity of isolated chloroplasts has been coupled to photosynthetic hydrogen evolution via methylviologen and a Clostridium hydrogenase. Rates of 125 μmol hydrogen evolved per mg chlorophyll and hour have been obtained. The conditions for such optimal activity suggest that a closed thylakoid vesicle is required in order to prevent side-and backreactions of reduced methylviologen, which compete with and reduce hydrogen evolution.
The Separation of High and Low Molecular Weight RNA by Precipitation with N-Cetyl- N,N,N-trimethyl-ammoniumbromide
Authors: Seibert Gerhard , Schöbel Barbara , Zahn Rudolf K. 
Published: August 2018

Abstract
RNA with a sedimentation constant of 28S and 18S can easily be separated from 4S and 5S RNA.
The method depends on the different solubulities of nucleic acids in solutions of the cationic detergent N-cetyl-N,N,N-trimethyl-ammoniumbromide at various ionic strengths. The separation can be achieved with high efficiency in one step.
Oscillatory Nervous Response and Transient Vibration (Ear of Locusta migratoria Acrididae, Insecta)
Authors: Adam L.-J. , Dahmen H. , Fastrich P. 
Published: August 2018

Abstract
The summed action potential (SAP) of the receptor axons in the tympanic nerve is a very regular, often nearly harmonic oscillation around an average level. The oscillation amplitude depends on the slope of the stimulus ramp, whereas the average level of the response is determined by the plateau of the ramp. Earlier hypotheses upon the tympanic SAP do not explain the above findings. Yet the transient solutions of a simple oscillator model reproduce the tympanic oscillations.
Benzo(a)pyrene Metabolites Formed by Plant Cells
Authors: Harms Hans , Dehnen Walter , Mönch Wolfgang 
Published: August 2018

Abstract
Benzo (a) pyrene, added to the nutrient solutions of cell suspension cultures of Chenopodium rubrum, was metabolized to oxygenated derivatives. With increasing time of incubation decreasing amounts of the added 14C-radioactivity could be extracted with 70% methanol or be isolated as benzo (a) pyrene. The amount of metabolites formed increased with increasing time of incubation. After 48 hours most of the radioactivity was found in the extracted residue. These observations and some other indications give reason to believe that some of the metabolites are linked to proteins or nucleic acids.
Metabolites of β, β-Carotene in the Stick Insect, C arausius morosus Br.: Compounds with 2-One and 3,4-Didehydro-2-one Structure
Authors: Kayser Hartmut 
Published: August 2018

Six novel keto carotenoids have been isolated from the stick insect. The structure of the pre­dominant red pigment has been assigned to 3,4,3′,4′-tetradehydro-β,β-carotene-2,2′-dione on the basis of electronic, infrared, and mass spectra. Minor pigments are 3,4-didehydro-β,β-carotene-2,2′-dione, 2′-hydroxy-3,4-didehydro-β,β-caroten-2-one, and 2′-hydroxy-β,β-caroten-2-one. Two other com­pounds, β,β-caroten-2-one and β,β carotene-2,2′-dione, have been tentatively identified. The ad­ ditional occurrence of β,β-caroten-2-ol and β,β-carotene-2,2′-diol has been reported recently. All hydroxylated pigments are mainly present as fatty-acid esters. During hydride reduction of the 3,4-didehydro-2-one compounds hydrogenation of the 3,4-double bond was observed as a side reaction.
A hypothetical scheme of carotenoid metabolism in the stick insect is proposed. According to this pathway the keto groups are introduced by a pseudo one-step reaction; the hydroxylated pig­ments are thought to be reduction products of the corresponding ketones. The proposed pathway is fitting more to physiological data than an alternative one based on the hydroxyl →carbonyl sequence.
Molecular Weight and the Dodecyl Sulphate Binding of a Thylakoid Membrane Polypeptide Involved in a Reaction on the Oxygen-Evolving Side of Photosystem II
Authors: Craubner Hans , Koenig Friederike 
Published: August 2018

Abstract
The molecular weight of a thylakoid membrane polypeptide with the apparent molecular weight 11 000 was determined by measurement of the sedimentation velocity, the diffusion and the ef­fective partial specific volume. The molecular weight was found to be 6300 and that of the poly-peptide-dodecyl sulphate micelle was found to be 11 200. The frictional ratio was 1.35. In ad­dition, we determined the binding of dodecyl sulphate onto the polypeptide by equilibrium dialysis. We found that 1 g polypeptide binds 0.77 g sodium dodecyl sulphate which corresponds to 17 molecules dodecyl sulphate bound per polypeptide chain. In the absence of dodecyl sulphate the polypeptide aggregates. The molecular weights of the aggregates are in 0.01 м sodium phosphate buffer pH 7.2 150 000 and in a 1 :1 mixture of 0.01 м phosphate buffer and 96% ethanol 365 000. The frictional ratios were 1.07 and 1.16 respectively which points at a spherical shape.
The experimental conditions for the determination of the dodecyl sulphate binding were critically scrutinised.
Isolation of Messenger Ribonucleoproteins from HeLa Cells by Affinity Chromatography on Poly (U) Sepharose
Authors: Liautard Jean-Pierre , Tromm Dagmar , Köhler Kurt 
Published: August 2018

Abstract
Polysomes of HeLa cells were adsorbed on Poly (U)-Sepharose columns. This adsorption is probably due to poly (A) sequences at 3′ terminus of the messenger. Stepwise elution initially removed ribosomal subunits thereafter mRNA and a set of proteins.
These proteins are identical with the main components of the polysomal messenger ribonucleo-protein particles described previously. Thus, this method allows their rapid and easy separation from ribosomal and other proteins.
Binding of Copper(II) to Proteins of the Photosynthetic Membrane and its Correlation with Inhibition of Electron Transport in Class II Chloroplasts of Spinach
Authors: Vierke Gerhard , Struckmeier Peter 
Published: August 2018

Abstract
Incubation of class II chloroplasts of spinach with copper in the light at pH = 8 in concentrations that inhibit oxygen evolution results in the formation of a copper (II) protein complex with the photosynthetic membrane. The EPR spectra indicate that the four nearest ligands to Cu(II) consist of three oxygen atoms and one nitrogen atom. The copper (II) protein appears to be pre­ dominantly associated with photosystem II. The formation of this protein as measured by the EPR signal amplitude of its room temperature spectrum correlates with the inhibition of oxygen evolution and of electron transport within photosystem I. This result indicates that the inhibition of photosynthetic electron transport by copper may be due to the formation of a copper (II) chelate with a membrane protein.
A Comparative Study of the Endocrine System of the Honey Bee Larvae under Normal and Experimental Conditions
Authors: Dogra G. S. , Ulrich G. M. , Rembold H. 
Published: August 2018

Abstract
The endocrine system of the honey bee (Apis mellifera L.) has been studied morphologically through post-embryonic development with several histological techniques. Marked differences in the structure of the neurosecretory complex of queen and worker larvae have been observed during larval stages. In queen larvae, morphogenesis of the neurosecretory cells, their axons and the formation of the chiasma takes place during end of 2nd and beginning of 3rd, in the workers at beginning of 4th larval instar. Stainable neurosecretory material was found in queen larvae at the beginning, in worker larvae at the end of 4th instar. In early larval stages, the corpora allata are more active in the queen. During initial 3 - 5 days of larval development the gland volume is reduced in both castes. After 36 to 48 hours of endocrine retardation, the glands become active again. The same histological effects are found under experimental conditions, where worker larvae of 2nd instar were reared in the incubator on basic food, Royal Jelly and with topically applied juvenile hormone I.
The Adenine and Thymine Molecules. Some Excited Singlet and Triplet Levels of the Normal and Tautomeric Forms
Authors: Marañon Julio , Sorarrain Oscar M. 
Published: August 2018

Abstract
The shape of the barrier for the H transfer between the normal and tautomeric forms have been determined for the adenine and thymine molecules. The correlations for several singlet and triplet states has been calculated using the CNDO/2-Cl method. The relative stability between both conformations and the agreement with some experimental values is also discussed.
Untersuchung der Rekombinationskinetik von photodissoziiertem Myoglobin-CO bei tiefen Temperaturen mittels Mössbauer-Spektroskopie / Investigation of the Recombination Kinetic of Photodissoziated Myoglobin-CO at Low Temperatures by Mössbauer Spectroscopy
Authors: Marcolin H. E. , Reschke R. , Trautwein A. 
Published: August 2018

Abstract
Myoglobin, Mössbauer Spectroscopy, Recombination Kinetic Myoglobin-CO (MbCO) has been photodissoziated with white and monochromatic light at low temperatures (5-40 °K). The photoproduct Mb* was identified with Mössbauer spectroscopy as ferrous high-spin complex, with isomer shift and quadrupole splitting, which are similar to the corresponding parameters of deoxymyoglobin. From the time-dependent change of the linewidth of the Mb*-Mössbauer-spectrum at 5 °K over a time-intervall of 7 hours we conclude, that there exist several slightly different Mb*-conformations with different recombination characteristics. In order to obtain a convenient time resolution of the recombination behavior, we investigate the time-dependence of one of the Mb*-absorptionlines with a Mössbauer drive of constant velocity. The resulting recombination data then are analzyed in various steps of approximation. It is shown that at least two independent exponentials are necessary for the interpretation of experimental data. The attempt to interprete the experimental data on the basis of distribution of energies is in qualitative agreement with corresponding results, which are derived from optical recombination data by Austin et al. Typical activation energies for the recombination process CO → Mb* are 2 kcal/mol. At low temperature (T < 46 °K) the recombination behavior is explained by quantum-mechanical tunneling.
Zur Frage der Bildung von Dimethylnitrosamin aus Tetracyclin-Derivaten bei der Nitrosierung in saurer Lösung / On the Problem of Dim ethylnitrosamine Form ation from Tetracycline-Derivatives by Nitrosation Reaction in Acidic Medium
Authors: Röper Harald , Heyns Kurt 
Published: August 2018

Abstract
The hydrochlorides from tetracycline and six tetracycline derivatives *-7-dimethylamino-6-des-methyl-6-desoxytetracycline [minocycline], 7-chlorotetracycline [chlorotetracycline], 7-chloro-anhy-drotetracycline [anhydrochlorotetracycline, 7-chloro-6-desmethyltetracycline [demethylchlorotetra- cycline], 5-hydroxytetracycline [oxytetracycline] and 6-desoxy-5-hydroxytetracycline [doxycycline] - were reacted with different amounts of sodium nitrite at 37 °C for two hours in aqueous buffer solutions at pH 2 and 4.
Dimethylnitrosamine formation was confirmed by gas-liquid chromatography and by combined gas-liquid chromatography/mass-spectrometry from minocycline, doxycycline, oxytetracycline and an- hydrochlorotetracycline.
Dimethylnitrosamine formation from minocycline and doxycycline was blocked by ascorbic acid. The catalytic effect of sodium thiocyanate for the dimethylnitrosamine formation from minocycline and nitrite was investigated.
The different reactivity of the investigated tetracycline derivatives towards nitrite in acidic solutions is discussed by stereochemical considerations in connection with the formation of hydrogen bridge linkages. This hypothesis was confirmed by dimethylnitrosamine formation from anhydro-chlorotetracycline and sodium nitrite at pH 2.