bluuebunny/crossref_metadata_2025 huggingface dataset:
Variability of Conductivity Changes in Black Phosphatidylserine Membranes Induced by Proteins from Erythrocyte Membranes
Authors: Bleuel H. , Wiedner G. , Schubert D.
Published: August 2018

The electrical conductivity of black phosphatidylserine membranes, in solutions of 100 mм NaCl, 10 mм sodium phosphate (pH 7.1), is strongly increased by the intrinsic proteins (“strongly bound” protein fraction) from human erythrocyte membranes. The magnitude of the conductivity increase is highly dependent on the maximum pH-value pH* used during the preparation of the protein (8.0≦ pH* ≦11.8). For each pH*, membrane conductivity λf and protein concentration c are linked by the equation λf=k·-cs, k and s being functions only of pH*. The value of s varies between 1.0 (pH* 8) and 4.0 (pH* 10). It is assumed that the protein-induced conducting sites, at least for protein pretreatment at pH* ≦ 10, are assembled from four protein subunits. The incorporation of the subunits into the lipid bilayer is supposed to occur either as the final tetramer (pH* 8) or as monomers (pH* 10) and possibly dimers (pH* around 9).
Transfer of Glycolipid between Membranes of Tissue Culture Cells, Using Dansylcerebroside as a Model
Authors: Huang Richard T. C.
Published: August 2018

Donor cells, which had incorporated dansylcerebroside in their membranes, could further transfer this glycolipid to monolayers of acceptor cells. The ease of transfer varied among acceptor cells, BHK cells being the best and MDBK cells the poorest acceptors of the cells tested.

The process of transfer seemed to be mediated by lipids rather than by proteins of the membranes. The mode of attachment between donors and acceptors, such as classified as loose contact, tight adhesion or binding by lectin, did not significantly influence the extent of glycolipid transfer. However, modification of plasma membranes by infection of acceptor cells with myxoviruses re­sulted in enhancement of glycolipid transfer in some cases.

Various factors have been evaluated with respect to dynamics of cellular membranes.
Notizen: Flavonol Glycosides of Carya pecan and Casuarina equisetifolia
Authors: El-Ansari Mohamed A. , Ishak Moheb S. , Ahmed Ahmed A. , Saleh Nabiel A. M.
Published: August 2018

The flavonol glycosides of Carya pecan and Casuarina equisetifolia were isolated and identified. The branches of C. pecan were found to contain azaleatin-3-arabinoside, azaleatin- 3-rutinoside, quercetin-3-glucoside and caryatin-3′- or -4′-glucoside. From the leaves of C. equisetifolia eleven glycosides of kaempferol and quercetin were identified.
Notizen: The Structural Components of Hog Cholera Virus
Authors: Enzmann P.-J. , Rehberg Hilde
Published: August 2018

Hog cholera virus grown in PK-15 cells and SK-cells was labeled with [35S] methionine and [3H] uridine. At least 3 polypeptides were resolved by polyacrylamide gel electro­ phoresis after disruption of the virus with sodium dodecyl-sulfate. The molecular weights of the structural proteins were determined to be 55000 (p55), 46000 (gp46), and 36000 (p36). The molecular weight of the viral RNA was determined to be about 4 X 106 in polyacrylamide-agarose-gel electrophoresis. In sucrose gradients the RNA has a S20,w value of 40 -45S.
Notizen Elektronenmikroskopische Untersuchungen an peritrophischen Membranen von Phyllopoden (Crustacea) /Electron-Microscope Study of the Peritrophic M embrane in Phyllopoda (Crustacea)
Authors: Schlecht Friedrich
Published: August 2018

The peritrophic membrane of Daphnia pulex, Daphnia magna, and Leptestheria dahalacensis consists of arbitrarily or hexagonal arranged fibrils. Peritrophic membranes of L. dahalacensis show in addition an orthogonal orientation. The development of these patterns by “self assembly”-processes can be excluded.
Notizen: Ray Path and Reflection Mechanisms in Crayfish Eyes
Authors: Vogt Klaus
Published: August 2018

In crayfish eyes image formation not due to refraction but to total internal and multilayer reflection in an orthogonal mirror system is described. Relevant optical parameters (geometry and refractive indices) in this eye are determined.
Abbau von Antipyrin durch Pyrazon-abbauende Bakterien / Degradation of Antipyrin by Pyrazon-Degrading Bacteria
Authors: Sauber K. , Müller R. , Keller E. , Eberspächer J. , Lingens F.
Published: August 2018

Bacteria with the ability to grow on pyrazon as sole source of carbon were isolated from soil. They also are able to grow on antipyrin. Then three metabolites of antipyrin can be isolated from the culture fluid which were identified as 2,3-dimethyl-1-(cis-2,3-dihydro-2,3-dihydroxy-4,6-cyclo- hexadiene-1-yl) -pyrazolone (5)(I), as 2,3-dimethyl-1-(2,3-dihydroxyphenyl) -pyrazolone (5) (II)and as 2,3-dimethyl-pyrazolone (5) (III), respectively. Compound I and II were used as sub­strates for enzyme studies. A dioxygenase catalyzes the enzymatic conversion of antipyrin into compound I. In the presence of NAD as cosubstrate compound I is transformed into compound II by a dehydrogenase. A pure preparation of metapyrocatechase from pyrazon-degrading bacteria converts compound II into the dephenylated heterocyclic moiety of antipyrin (III) and into 2- pyrone-6-carboxylic acid. Based on the results of the enzymatic studies a pathway for the degrada­tion of antipyrin is proposed.
Artificial Phospholipid and Glycolipid Particles, Visualization of Their Structures by Fluorescence Markers and Some Biological Properties Expressed by These Particles
Authors: Huang Richard T. C.
Published: August 2018

Homogeneous large (5 - 30 μm) lipid particles com­ parable in size and shape to blood cells can be obtained when excess of cholesterol is homogenized with egg phospholipids or brain glycolipids in a Dounce apparatus. The particles contain distinct structures of membranes and lipid cores as visualized by the included fluorescence markers.

When these particles were used as models in studying interactions between membranes, it was demonstrated that several properties norm ally pertaining to natural membranes could be exhibited by lipids alone. It could also be shown that particles containing phospholipids or glycolipids were very different in their adhesiveness to tissue culture cells and in their response to sera of various species.
Scattering of X-Rays by Parallel and Antiparallel Layers in Disordered Stacking and Statistical Layer Shift for a-Chitin
Authors: Haleem M. Abdul , Astbury K. D. Parker
Published: August 2018

Statistical Layer Shift, α-Chitin The intensities scattered by antiparallel/parallel layers were calculated. Difference synthesis maps allowing for statistical layer shifts were computed for a-chitin. The results support the view that there may be antiparallel sequence with each layer displaced at random by +e or -e from a halving position in the ϰ-direction. This is supported by greater breadth of certain reflection of the type lkl compared to 0kl on the X-ray diffraction photograph. This gives strong evidence for some imperfection in the ϰ-direction and the proposed indeterminacy + e is one possible way in which this might arise.
Tectograndinol, ein neues Diterpen aus Tectona grandis L. fil. / Tectograndinol, a New Diterpene from Tectona grandis L. fil.
Authors: Rimpler Horst , Christiansen Ilona
Published: August 2018

Tectona, Verbenaceae, Diterpene, Tectograndinol Tectograndinol (1), a new diterpene has been isolated from leaves of Tectona grandis. Its structure and configuration is elucidated by spectroscopic methods and some chemical reactions.
P1, P5-Bis-(5′-adenosyl)pentaphosphate: Is this Adenylate Kinase Inhibitor Substrate for Mitochondrial Processes?
Authors: Köhrle Josef , Lüstorff Joachim , Schlimme Eckhard
Published: August 2018

1. P1, P5-Bis-(5′-adenosyl)pentaphosphate (Ap5A) inhibits “soluble” adenylate kinase even when this enzyme is an integral part of the complete mitochondrion. The Ki is 10-5м , i. e. about two orders of magnitude higher than the inhibitor constants determined for the purified adenylate kinase of rabbit muscle and an enzyme preparation separated from the mitochondrial intermembrane space. The weaker inhibitory effect is due to a lower accessibility of the enzyme.

2. As to be expected Ap5A which is of the “multisubstrate analogue”-type does not affect mito­ chondrial nucleoside diphosphate kinase.

3. Though Ap5A owns the structural elements of both ATP and ADP it is not a substrate of the adenine nucleotide carrier, i.e. neither it is exchanged across the inner mitochondrial membrane nor specifically bound.

4. Ap5A is not metabolized by rat liver mitochondria.
Chirality of the Hydrogen Transfer to NAD Catalyzed by (3R)Hydroxybutyrate Dehydro­genase from Pseudomonas lemoignei
Authors: Alizade Miguel A. , Gaede Karl
Published: August 2018

The chirality of the hydrogen transfer from (3R) hy­ droxybutyrate to NAD catalyzed by (3R) hydroxybutyrate dehydrogenase (E.C. 1.1.1.30, ᴅ-3-hydroxybutyrate : NAD oxidoreductase) from Pseudomonas lemoignei was investi­ gated. [4-3H ]NAD was enzymatically reduced to (4R) [4-3H ]NADH with (3RS) hydroxybutyrate. This observation was confirmed since NAD could be reduced to (4S) [4-3H] NADH with (3RS) [3-3H] hydroxybutyrate and (3R) hy­ droxybutyrate dehydrogenase. From these experim ents it can be concluded that (3R) hydroxybutyrate dehydrogenase from P. lem oignei should be classified as an B or (S) type dehydrogenase.
Nonthermal Effects of Millimeter Microwaves on Yeast Growth
Authors: Grundier W. , Keilmann F.
Published: August 2018

Weak microwave irradiation of aqueous yeast cultures was found to affect their growth rate in a frequency-selective manner. Depending on frequency (near 42 GHz), both increases and de­ creases of the growth rate were observed. The resonance bandwidths are of the order of 0.01 GHz. Simple thermal effects can be excluded. These findings support theoretical predictions of coherent molecular oscillations activating metabolic processes.
Untersuchung der kristallinen Strukturen in Depotfetten von Tieren mittels Röntgenbeugungsmethoden / Investigation of Crystalline Structures in Fats of Animals by X-Ray Scattering
Authors: Wawra H.
Published: August 2018

Fat-praeparates of cow and pork have been investigated by small-angle X-ray scattering methods. Dependent on the temperature these fats show distinct X-ray interference patterns in the small-angle region. Hence complete phasediagrams of the fats in the temperature region between -20 °C and 55 °C could be estimated. Using the intensity distribution of the X-ray scattering the electron-density distribution along one direction of the ground-cells of the fat crystals were calculated.
Influence of Molecular Conformation on the Solid State Packing of 1,2-Diglycerides Study of 1,2-Dipalmitin and Some Structural Analogs by Electron Diffraction, X-Ray Diffraction, and Infrared Spectroscopy
Authors: Dorset Douglas L. , Pangborn Walter A. , Hancock Anthony J. , Lee Iris S.
Published: August 2018

Diffraction studies on natural 1,2-dipalmitin and on analogs, including those based on the configurational isomers of cyclopentane-1,2,3-triol reveal that the 1,2-diglycerides crystallize from solvent with chain methylene packing identical to the monoclinic form of even-chain alkanes. The chains probably are folded back in “hairpin” fashion as found in phospholipid crystal structures. Acyl shifts are observed to occur in the crystalline solid state at room temperature to give the 1,3-diglyceride. Analogs based on the above-mentioned cyclitols show that isomers with adjacent chains trans to the ring (possibly extended chain packing) or with chains cis to the ring (“hair­ pin”) crystallize readily. Both possibly extended chain configurational isomers have the α-form as well as β′-forms and a β-polymorph. The hairpin isomers each give a β′-polymorph but only the all-cts isomer gives an α-form.
Protein Patterns during Sporulation in Fission Yeast
Authors: Friedmann K. L. , Egel R.
Published: August 2018

Various strains (wild-type and mutants) of Schizosaccharomyces pombe were subjected to sporulation conditions, and analysed with regard to changes in their protein patterns. Trisbuffer-soluble proteins (TS) and DNA-binding proteins (DB) were denatured and separated by polyacrylam ide electrophoresis. A fter endogenous nitrogen depletion (the apparent trigger of conjuga­tion and sporulation) the following alterations were observed: larger TS-proteins were proteolytical-ly degraded; the pattern of DB-proteins underwent several selective changes (reduction, enforce­ ment, or new appearance of individual bands) ; an endonucleolytic DNase activity appeared. Most of these changes were expressed before conjugation, and did not appear in sterile strains. They could, however, be provoked by an abrupt shift to nitrogen-free medium, even in sterile strains. Inhibition studies with cycloheximide revealed at least two phases of protein synthesis specifically needed for sporulation: a very sensitive phase before conjugation, and a more resistant phase lasting until 0.5 h before spore form ation. Medium exchange between heterothallic cultures (h+ and h-) effected certain sporulation-specific alterations of the DB-protein pattern, indicative of diffusible mating-type factors in the culture fluid.
Isolation and Identification of 3-Octanone in the Essential Oil of Rosmarinus officinalis L.
Authors: Koedam Arthur , Gijbels Marion J. M.
Published: August 2018

The essential oil of freshly distilled leaves of Rosmarinus officinalis L. was found to contain 3-octanone, a compound hitherto not reported to be present in this oil. Identification was established by comparing the gas chromatographic retention time and by mass spectrometry.
Influence of Ions and Chelating Agents on the Haemolymphacetylcholinesterase of Mytilus edulis
Authors: Wachtendonk Dettmar von , Neef Jutta
Published: August 2018

By use of different inhibitors as well as atomic absorption spectrophotometry it has been shown that the haemolymph-acetylcholinesterase (E. c. 3.1.1.7) of the sea mussel Mytilus edulis is a me- talloprotein containing 2,95 Fe2+ -ions per subunit. All inhibitors used (1,10-phenanthroline, salicylic aldehyde, 2,2′-dipyridyl, 8-hydroxyquinoline) showed a non-competitive inhibition, which was not pH- dependent. Some divalent cations caused a marked increase of the enzyme activity, some heavy metals inhibited the enzyme almost completely; monovalent inorganic cations did not influence the enzyme at all. Besides NaF and Na2SiF6, which showed a non-competitive inhibition comparable to the inhibition observed with the chelating agents, and NaN3 , whose mode of action was not identifiable, no inhibition by different mono- and divalent inorganic anions was to be observed. Ammonium ions caused no enzyme inhibition, but length the inhibition power of substituted ammonium ions increased with an increasing C-chain. The influence of some organic solvents on the enzyme activity is demonstrated.
Kinetic Investigations of the Autoxidation of Adrenalin
Authors: Bors W. , Michel C. , Saran M. , Lengfelder E.
Published: August 2018

Generation rates of superoxide anions (O2
-) by autoxidizing adrenalin at pH 9.5 were deter­mined in solutions containing either superoxide dismutase (0.85 м-1 s-1) or hydroxylamine (0.0185 м-1 s-1) as competitive scavengers. The rate constants of O2
- with adrenalin and hydroxyl­amine were calculated for neutral and alkaline solutions. The respective values were for adrenalin: 5.6 ×104 м-1 s-1, pH 7.8; 7.0 × 103 м-1 s-1, pH 9.5 - and for hydroxylamine 5.9 × 104 м-1 s-1, pH 7.8; 3.4 ×104 м-1 s-1, pH 9.5. The effects of various competitors and O2
--sources on the rate constants were compared.
Sensitive Radioimmunoassay for Detection of O6-Ethyldeoxyguanosine in D N A Exposed to the Carcinogen Ethylnitrosourea in vivo or in vitro
Authors: Müller Rolf , Rajewsky Manfred F
Published: August 2018

O8-ethyl-2′-deoxyguanosine (O8-EtdGuo) is a major premutational product formed in both in­tracellular DNA and in purified DNA in vitro, after exposure to the potent alkylating carcinogen N-ethyl-N-nitrosourea (EtNU). Antibodies directed against O8-EtdGuo were obtained by immunizing rabbits with a conjungate of O6-EtGuo and bovine serum albumin. In a competitive radioimmuno­assay (RIA), with O8-Et[8,5′·3H]dGuo as a tracer and various alkylated and natural nucleic acid components as inhibitors, these antibodies show high specificity for O6-EtdGuo and detect this product at a level of 0.3 picomol (antibody association constant, 7×108l/mol). In a sample of 130 μg of hydrolyzed DNA, O6-EtdGuo can thus be measured at a molar ratio of O8-EtdGuo/2′- deoxyguanosine of about 3×10-8, i. e., about 5×103 O8-EtdGuo molecules per diploid cell. Exam­ples are given for the quantitation of Oe-EtdGuo in DNA exposed to EtNU in vivo or in vitro.
High-Temperature Inactivation of Passive Potassium Transport in Electrically Non-Excitable Cells
Authors: Ernst M. , Adam G.
Published: August 2018

High-temperature inactivation of passive potassium transport is demonstrated for mouse cell cultures and discussed in analogy to recent results on model systems from phospholipid/cholesterol doted with channel-forming antibiotics.
Über die circadiane Variation der Stoffwechselgröße des isolierten Gewebes / Circadian Rhythm of Metabolie Rate in Isolated Tissue
Authors: Schmidt H. J.
Published: August 2018

The circadian variation of oxygen uptake of isolated mouse diaphragm has been measured by means of the direct Warburg-technique in two series with sets of each 8 successive experiments. Under our experimental conditions oxygen uptake in the isolated diaphragm remains constant for 5 hours at least. The 24-hour period could therefore be completed with 8 single measurements of each 10 - 20 isolated diaphragms started at 3 h intervals with a overlap in experimental time of 2 h hours between each single experiment. Similar to the results concerning the spontaneous locomotive activity of the mouse (ASCHOFF 1955) we found maximum values of metabolic rate during the night, minimum values during day time and a interpolated relative maximum of oxygen uptake between 600 -800 h. Oxygen uptake after the stabilisation period of approximately 1 h seems to be determined by the time of the death of the animal.
Strahleninduzierte Aggregatbildung von Proteinen: Bindung von Aminosäuren an Myoglobin / Radiation-Induced Aggregation of Proteins: Binding of Amino Acids to Myoglobin
Authors: Jakubick Vera , Delincée Henry
Published: August 2018

When myoglobin is irradiated in the presence of amino acids, the most radiation-reactive species, like the aromatic and sulfur-containing amino acids, will bind preferentially to the protein. The radiation-induced binding is strongly dependent on the concentration of protein and amino acid. Subsequent to irradiation of myoglobin in the presence of radioactively labelled tryptophan followed by tryptic hydrolysis, only a single radioactive spot was detected on the fingerprint. The binding of amino acids is thus not randomly distributed over the protein molecule but occurs at specific reactive sites.
Untersuchungen über spezifische Einflüsse des Serums und Lebercytoplasmas auf den [3H]TTP-Einbau isolierter Leberzellkerne / Studies on the Specific Effects of Serum and Cytoplasm of the Liver on the [3H]TTP-Incorporation of Isolated Liver Nuclei
Authors: Strasser R. , Volm M.
Published: August 2018

Previous authors have described that liver cytoplasm and serum from partially hepatectomized rats stimulate the DNA synthesis of isolated nuclei of liver cells. The aim of our investigation was to prove whether such stimulating effects are part of a specific regulation of growth. The sera and the cytoplasm supernatant 105 000Xg) were isolated at several intervals after partial hepatectomy and laparotomy and were tested on isolated nuclei of liver cells from adult rats partially hepatectomized 20 hours before. The supernatants isolated at 8 and 16 hours after both partial hepatectomy and laparotomy have a significant stimulatory effect on the [3H]TTP-uptake by nuclei.

The presence of serum (10%) causes a general elevation (75%) of the [3H]TTP-uptake by isolated nuclei. The sera isolated 4 to 12 hours after operation from both partially hepatectomized and laparotomized rats have an additional stimulatory effect on the [3H]TTP-uptake synthes of nuclei. In no case did the sera and liver cytoplasm of partially hepatectomized rats have a significantly different and therefore “specific” effect on the nuclear DNA synthesis.

Additional experiments showed that frozen and thawed nuclei of liver cells respond only to the nutritive power but not to the stimulatory effects of the sera. Thus, thawed nuclei cannot be used for growth investigations.
Neue Anthrachinonfarbstoffe aus Cortinarius armillatus und C. miniatopus (Agaricales) [1] / New Anthraquinone Pigments from Cortinarius armillatus and C. miniatopus (Agaricales) [1]
Authors: Besl Helmut , Haibauer Richard , Steglich Wolfgang
Published: August 2018

Acids A reinvestigation of the velum pigments of Cortinarius armillatus yielded the new anthraquinonecarboxylic acids endocrocin-6,8-dimethyl ether (4) and dermorubin-6-methyl ether (8).
Degradation of Pisatin by Fungi of the Genus Fusarium
Authors: Lappe Ulrich , Barz Wolfgang
Published: August 2018

Fifteen strains of Fusarium previously shown to degrade flavonoids and isoflavonoids were investigated for pisatin degradation. Fusarium anguioides and Fusarium avenaceum converted the phytoalexin (1) to the nontoxic 3,6a-dihydroxy-8,9-methylenedioxypterocarpan (2).
Multiple Functions of Thioredoxins
Authors: Wagner Wolfgang , Follmann Hartmut , Schmidt Ahlert
Published: August 2018

Reduced thioredoxins from microbial and plant cells, both of cytoplasmic or chloroplast origin, are interchangeable in stimulating such diverse enzyme activities as ribonucleoside diphosphate reductase (E. coli) , PAPS sulfotransferase (Synechococcus), and fructose-1,6-bis-phosphatase (from spinach) in vitro. It is suggested that reduced thioredoxins are unspecific, multifunctional cellular proteins while in contrast the oxidized froms require specific enzymes for their reduction.
Antisera to the Coupling Factor of Photophosphorylation and Its Subunits
Authors: Koenig Friederike , Radunz Alfons , Schmid Georg H. , Menke Wilhelm
Published: August 2018

Stroma-freed chloroplasts were extracted with sucrose palmitate-stearate containing buffer. After the addition of dodecyl sulfate and mercaptoethanol to the extract a series of polypeptides was isolated from the mixture by gel filtration. These polypeptides were later used for immunization. Antisera to four polypeptides reacted in the Ouchterlony double diffusion test with authentic coupling factor yielding a precipitation band. According to the observed apparent molecular weights the polypeptides are the α, β , δ and ε subunits of the coupling factor. An antiserum to the γ subunit has been obtained already previously.

All antisera inhibit photophosphorylation reactions and electron transport considerably. Addition of gramicidin inhibits photophosphorylation completely whereas gramicidin restores electron transport in the assays with the antisera to the α, β , γ and δ subunit. In the case of the antiserum to the ε subunit gramicidin does not regenerate electron transport. As in the presence of the serum to the ε subunit pH changes in the suspension medium are not observed, this serum seems to open a proton channel. Also, upon addition of dicyclohexyl carbodiimide (DCCD) pH changes in the suspension medium in the assay with antiserum do not reoccur. According to these unexpected results the identity of the antigen with the ε subunit of the coupling factor is not certain.

ATP-ase reactions are only inhibited by the antisera to the α and γ subunit and what is thought to be the ε subunit. The antiserum to the α subunit uncouples electron transport as the only one when used in sufficient concentrations. The dosis-effect curves of the inhibition of the electron transport exhibits a maximum. The dosis-effect curves for the other components rise after a lag phase in an approximately hyperbolic manner. The inhibitory action on electron transport is exerted by all antisera in the region of the reaction center I or in its immediate vicinity. This is thought to be due to the fact that a protein of the reation center I is inhibited in its function by the increasing proton concentration inside the thylakoid. The inhibition of electron transport by the antiserum to the ε subunit is considered to be a direct serum effect.

Besides the increase in fluorescence yield, due to the inhibition of electron transport in the region of photosystem I, decreases of the fluorescence yield are observed in the presence of DCMU, which do not depend on the redox state of Q but rather on the condition of the thylakoid mem­brane. Moreover, the antisera affect in a differing manner the energy spill-over of excitation from photosystem II to photosystem I.
Extracellular Calcium, Magnesium, and Sodium Ion Competition in the Conductance Control of the Photosensory Membrane of Limulus Ventral Nerve Photoreceptor
Authors: Stieve H. , Bruns M.
Published: August 2018

The membrane potential in the dark and the saturated response height of the ventral nerve photoreceptor of Limulus was measured by an intracellular electrode while the external concentration of calcium, magnesium and sodium ions was varied.

Decreasing the extracellular calcium concentration from 10-2 mol/l causes a calcium-dependent lowering of the dark membrane potential and at very low concentrations (<10-8 mol/l a reversal to ca. +5 to +11 mV, if the external magnesium concentration is also low. Also, the light response diminishes with decreasing extracellular calcium concentration and disappears at a concentration of 10-9 mol/l.

External magnesium can substitute for certain properties of extracellular calcium.

Lowering the extracellular sodium concentration from 543 mmol/l to 30 - 50 mmol/1 reduces the dark membrane potential and the light responses at normal calcium concentration, whereas at low calcium concentration it causes a substantial rise of both.

Interpretation: The results are in accordance with our working hypothesis that a strong reduction of the external calcium (and magnesium) concentration causes a calcium concentration dependent opening of “ light channels” in the dark. Additional lowering the extracellular sodium concentration counteracts this effect; opening and closing of light channels is controlled by negative binding sites on the cell membrane for which calcium and sodium ions compete with an antagonistic action.
Phytotoxic Action of Paraquat on the Photosynthetic Apparatus
Authors: Böger Peter , Kunert K. J.
Published: August 2018

Treatment of microalgae (Bumilleriopsis) with paraquat (1,1-dimethyl-4,4-dipyridylium dichloride) under culture conditions in the light for 20 or 160 h leads to light-induced oxygen uptake and more or less severe chlorophyll bleaching, which is accompanied by formation of malondial-dehyde. The ratio of chlorophyll to packed chloroplast volume remains about the same as that of the control, presumably indicating destruction of membranes concurrently with pigments. Unre­lated to retardation of growth, degree of bleaching or to the formation of malondialdehyde quite a uniform degree of inactivation (≈ 50%) of partial redox reactions is observed in the region of photosystem II and I except for the terminal part of photosystem I (pigment 700 → NADP+) . The action of paraquat in the cell centers primarily on the photosynthetic membrane system and redox chain.
Quantitative Structure-Activity Relationship of Substituted Benzoquinones as Inhibitors of Photosynthetic Electron Transport
Authors: Oettmeier Walter , Reimer Susanne , Link Klaus
Published: August 2018

1.4-benzoquinones have been tested for their inhibitory activity on photosynthetic NADP+ reduction by chloroplasts. Benzoquinones with one or two branched alkyl side chains are inhibitors of electron flow. Inhibitory activity can be highly increased if one - and even more if two - halogen substitutents are introduced into the quinone moiety. Iodine substitution yields a better inhibitor than bromine than chlorine. A quantitative structure activity relationship according to a bilinear model, as developed by Kubinyi, with the lipophilicity as the only parameter could be established.
Symmetric and Asymmetric Bilayers of Retinal
Authors: Rich Marvin , Brody Seymour Steven
Published: August 2018

Asymmetric and symmetric bilayer membrane were formed from monolayers of egg lecithin and various retinal isomers. Capacitance of the asymmetric all-trans retinal/lecithin bilayer is 1.2 ± 0.1 µF/cm2. Asymmetrically formed membranes of 13-cis retinal/lecithin and 9-cis retinal lecithin were found to be 0.83 ± 0.06 and 0.56 ± 0.05 µF/cm2, respectively. Formation of bilayers of the various cis isomers appears to require the presence of solvent. Irradiation of the various retinal/lecithin films, under the proper conditions, leads to bilayers with marked changes in capacitance and conductance.
Notizen: Phenolics from Larix Needles XIV. Flavonoids and Phenolic Glucosides and Ester of L. decidua
Authors: Niemann Gerard J. , Baas Wim J.
Published: August 2018

Eleven flavonoids, four phenolic glucosides and one sugar ester were isolated from needles of Larix decidua and identified as: kaempferol, its 3-arabinoside and 3-rutino-side, quercetin-3-arabinoside, isorhamnetin-3-arabinoside and 3-(p-coumarylglucoside), laricitrin-3-glucoside and -3-rutino-side, myricetin-3-glucoside, syringetin-3-glucoside and apigenin-7-glucoside; the β-glucosides of p-hydroxybenzoic acid, vanillic acid, p-coumaric acid and ferulic acid, and the glucose ester of vanillic acid.
Notizen: Stepwise Methylation of Quercetin by Cell-Free Extracts of Citrus Tissues
Authors: Brunet Gunter , Saleh Nabiel A. M. , Ibrahim Ragai K.
Published: August 2018

The cell-free extracts of peel, root, or callus tissues of citrus catalyzed the stepwise O-methylation of quercetin to rhamnetin, isorhamnetin and rhamnazin. Both rhamnetin and isorhamnetin were further methylated to rhamnazin and possibly to a trimethyl ether derivative of quercetin. The results seem to indicate the existence of both meta and para directing enzymes that are involved in the biosynthesis of methylated flavonoids in citrus tissues.
Investigations on Hoya species, II. Latex Lipids and Leaf Phenolics of Hoya bella Hook
Authors: Baas Wim J. , Niemann Gerard J.
Published: August 2018

In Hoya bella latex a number of triterpenols were found, both in the free form and as esters. The main triterpenols were β-amyrin, cycloartenol, lupeol and the rarely occurring isobauerenol; esters of these alcohols which included cinnamic acid, propionic acid and isovaleric acid were identified. A homologous series of alkanes with carbon chain length ranging from C-20 to C-31 was found. In leaf extracts acylated flavonol glycosides as well as free ferulic acid occurred; the concentration of the latter decreased with increasing leaf age.
Purification, Subunit Structure, and Kinetics of the Chloroform-Released F1ATPase Complex from Rhodospirillum rubrum and Its Comparison with F1ATPase Forms Isolated by Other Methods
Authors: Müller Hans Werner , Schwuléra Udo , Salzer Manfred , Dose Klaus
Published: August 2018

A stable and homogeneous adenosine-5ʹ-triphosphatase (ATPase, EC 3.6.1.3) has been solubilized from Rhodospirillum rubrum (R . rubrum) chromatophores by chloroform extraction. Purification of the Ca2+-dependent ATPase activity was 200-fold. Ca2+ can be replaced by Mg2+, Cd2+, and Mn2+ .The Km for Ca-ATP (0.17 mᴍ) is increased about 5-fold during solubilization of the enzyme, whereas the Km values for Mg-ATP (0.029 mᴍ) and Cd-ATP (0.014 mᴍ) are not affected.

The chloroform-released ATPase has a molecular weight of 400,000 ± 30,000 and consists of the following subunits (molecular weights in parenthesis): α (58,000), β (53,500), γ (39,000), δ (18,500), and ε (14,000). The amino acid composition and the fluorescence spectra are presented.

Besides the chloroform-released ATPase complex three other Ca2+-dependent ATPase forms have been isolated from R. rubrum chromatophores by other methods for comparison. Ultrasonication of the membranes leads to the release of an ATPase complex which is mainly composed of α, β, and γ-subunits. From an acetone powder extract an ATPase complex could be purified by affinity chromatography which is composed of four kinds of subunits (α, β, γ, δ). The same acetone powder yields an ATPase consisting of only three different types of subunits (α, β, γ) if the final purification step is preparative disc electrophoresis on 6% polyacrylamide gels instead of affinity chromatography.
Enhanced Melanization of Harding-Passey Mouse Melanoma Cells Following Treatment with Exogenous Melanosomes in Monolayer Culture
Authors: Leising H. B. , Schachtschabel D.O.
Published: August 2018

Purified melanosomes isolated from subcutaneously growing Harding-Passey melanomas of NMRI-mice were labeled either in vitro with [14C] tyrosine or [14C]DOPA in the melanin portion, or in vivo in the melanin and protein portion following i. p. injection of [14C] tyrosine. Treatment of monolayer cultures of Harding-Passey melanoma cells (HPM-73 line) with such labeled melanosomes resulted in rapid uptake of label during the first 4 h which leveled off thereafter. A portion of the “incorporated” label could be removed by a 15 min chase with unlabeled melanosomes.

Uptake of labeled melanosomes by HPM-73 cells was followed by increased cellular melaniza­tion which was not only due to melanin derived from incorporated melanosomes but primarily to newly formed melanin. Tyrosinase activity was elevated in melanosome-treated cells. Tyrosinase activity of control cells was significantly reduced following a 24 h exposure to actinomycin D or cycloheximide. On the other side, the same inhibitor treatment of melanosome-pretreated cells resulted in less inhibition of tyrosinase activity.

The present findings suggest “melanophagic” properties of cultured melanoma cells resulting in enhanced melanogenesis after phagocytotic uptake of functionally active exogenous melanosomes.
Notizen: A Revised Structure for the Phytoalexin Cajanol
Authors: Ingham John L.
Published: August 2018

Peroxide oxidation of cajanol ethyl ether afforded the B ring derived product, 2-methoxy-4-ethoxybenzoic acid. For­ mation of this compound means that the structure of cajanol, a major phytoalexin from Cajanus cajan, must be revised to 5,4ʹ-dihydroxy-7,2ʹ-dimethoxyisoflavanone.
Types of Selective Action by Herbicides which Inhibit Photosynthesis
Authors: Oorschot J. L. P. van
Published: August 2018

Herbicide Selectivity, Photosynthesis Inhibitors, Accumulation, Inactivation, Chloroplast Sensitivity Various sources are involved in the selective action of herbicides which inhibit photosynthesis, ranging from gross morphological differences connected with the availability of the herbicide to the foliar or root surface, to differential absorption, translocation and inactivation in the tissues of various plants species, and finally to differences in susceptibility at the chloroplast level. Their significance is reviewed with respect to the selectivity in the field.
Mechanism of Action of the Herbicide 4,6-Dinitro-o-cresol in Photosynthesis
Authors: Rensen J. J. S. van , Hobé J. H.
Published: August 2018

The herbicide 4,6-dinitro-o-cresol inhibits electron transport to ferricyanide and non-cyclic photophosphorylation for 50% at about 15 μm. At higher concentrations the photosystem I depen­dent Mehler reaction ascorbate/dichlorophenolindophenol to methyl viologen is stimulated, while cyclic photophosphorylation is inhibited. The herbicide thus is an inhibitory uncoupler.

Although the chemical structure of 4,6-dinitro-o-cresol is different from that of the diuron-type herbicides, its site and mechanism of action is similar. Both 4,6-dinitro-o-cresol and diuron inhibit electron transport between the primary electron acceptor of Photosystem II and the plastoquinone pool. This causes a closing of the reaction centers of Photosystem II. The interaction with the inhibited molecule however is different for the two herbicides.
Die Kooperativität bei der CO2-Hb-Bindung: Messungen mit Hilfe der 13C-NMR-Spektrometrie / The Cooperativity of the CO2 Hb Binding: Measurement by 13C -NMR Spectrometry
Authors: Burkhard O. , Barnikol W. K. R.
Published: August 2018

The detailed structure of the CO2 Hb binding curve is of considerable physiological interest, because the carbamino derivates, which are formed by the reaction of CO2 with Hb, are respon­sible for the well known Haldane effect.

Under physiological conditions CO2 binds to the four terminal NH2-groups of the protein chains of Hb and it is generally assumed, that there exists no cooperativity between these groups.

To examine whether this assumption is correct or not, we have measured the CO2Hb binding curve over a wide PCO2-range (from 0 kPa to about 70 kPa) by using 13C-NMR spectrometry. Morrow and coworkers (1976) have shown that carbamino-Hb causes a specific NMR signal. The quantitative analysis of the NMR spectra were done according to the method of internal standard. By analyzing mixtures of known composition, we were able to show that this method is working. So we had to use the following equation:

Z is the CO2 saturation of Hb, I is the intensity of the carbamino signal, and IHb is the intensity of the carbons of Hb, which are involved in the amide binding. (I/IHb)max is (I/IHb) at high PCO2, where Hb is completely saturated by CO2.

For our experiments we used solutions of human desoxygenated Hb, which were equilibrated with a mixture of N2 and CO2.

The CO2 contained 90% 13C-isotope. The pH was adjusted by titration to 7.2. The NMR measurements were mainly done with a Varian XL 100 NMR spec­trometer. The CO2 Hb binding curve, we have measured, is S-shaped and has an average Hill value (n̅) of 2.1. This result is quite striking with respect to the findings of other groups. A Hill value of 2.1 proves that CO2 like O2 binds to Hb in a cooperative manner. The discrepancy to the results of other groups may be explained by the fact that these authors measured the CO2 Hb binding curve only at comparatively low PCO2. In our opinion one can only get reliable n-values from the whole CO2 Hb binding curve.
Herpetriol and Herpetetrol, New Lignoids Isolated from Herpetospermum caudigerum Wall
Authors: Kaouadji Mourad , Favre-Bonvin Jean , Mariotte Anne-Marie
Published: August 2018

Two new compounds derived from coniferyl alcohol have been isolated from Herpetospermum

caudigerum Wall. Their structures have been established by spectral analysis (UV, PMR, CMR and MS).
Molybdocen-dichlorid als Antitumor-Agens / Molybdocene Dichloride as an Antitumor Agent
Authors: Köpf-Maier Petra , Leitner Manfred , Voigtländer Rolf , Köpf Hartmut
Published: August 2018

The antitumor activity of molybdocene dichloride is tested against Ehrlich ascites tumor in CF1 mice. The application of 75 or 100 mg/kg 24 h after transplantation achieves 100% tumor inhibi­tion until day 30.

Following the d0 and d1 metallocene dichlorides of titanium and vanadium, molybdocene dichloride is the First analogous d2 system revealing similar antineoplastic properties.
Empirical Border Lines of the Apatite Stability Field in the System CaO—P2O5—H2O —Na2O—CO2—MX at Room Temperature
Authors: Driessens F. C. M. , Dijk J. W. E. van , Borggreven J. M. P. M.
Published: August 2018

Literature data on equilibria between solid calcium phosphates having the apatite structure and aqueous solutions containing Na+ and CO3
2- ions were reexamined in view of the present data about the complexation of ions in such systems. Recalculations showed that all solutions were undersaturated or just saturated with respect to either brushite or octocalciumphosphate or more or less finely dispersed calcite and supersaturated with respect to pure hydroxylapatite. Sections through the quasi-sextary phase diagram were constructed which are representative for the system under simulated in vivo conditions.
NADPH-Dependent Thioredoxin Reductase and a New Thioredoxin from Wheat
Authors: Suske Guntram , Wagner Wolfgang , Follmann Hartmut
Published: August 2018

An album in fraction extracted from wheat flour contains thioredoxin reductase (Mr = 65,000) and a heat-stable thioredoxin (Mr = 15,000) which are separated on DEAE cellulose and further purified by gel filtration. W heat thioredoxin stimulates E. coli ribonucleotide reductase but not chloroplast fructose-bis-phosphatase. The enzyme is NADPH -dependent (Km = 3.2 X 10-6 ᴍ) . In presence of the thioredoxin it slowly reduces other proteins like insulin or ribonuclease. Therefore it is most likely identical with a protein disulfide reductase (of unknown specificity) previously described in wheat. This new thioredoxin system is a counterpart of the ferredoxin-dependent system found in photosynthetic plant cells, suggesting different, specific mechanisms for regeneration of reduced thioredoxins in germinating seeds and green plants.
Effect of Divalent Cations on Cation Fluxes Across the Chloroplast Envelope and on Photosynthesis of Intact Chloroplasts
Authors: Demmig B. , Gimmler H.
Published: August 2018

The effect of divalent cations on cation fluxes across the chloroplast envelope and on photo­ synthetic reactions of intact spinach chloroplasts was investigated.

In the absence of EDTA, divalent cations inhibited photosynthetic CO2-fixation and PGA-reduction at low PGA concentrations, but had almost no effect on the reduction of OAA, BQ, and on PGA-reduction at high PGA concentrations. The inhibitory effect of Ca2+ was greater than that of Mg2+. Inhibition of photosynthesis was greater when the divalent cations were added in the dark than when added in the light. In spite of its inhibitory effect, Mg2+ partially restored the Ca2+ inhibited photosynthesis, indicating the involvement of a Mg2+/Ca2+ antagonism in the inhibitory effect.

The inhibitory effect of divalent cations is stronger in a medium with low concentrations of K+ than in the presence of 20 - 50 mᴍ KCl. Mg2+ induced a release of plastidal K+ and an in­ crease of stromal H+ concentration.

The results indicate that external Mg2+ in the absence of EDTA does not influence neither photosynthetic electron transport nor photophosphorylation, but inhibits the light activation of some enzymes of the carbon reduction cycle. The latter is assumed to be due to an acidification of the stroma pH and the decrease of endogenous K+ level. Since the chloroplast envelope has only a very low permeability towards Mg2+, possible mechanisms are discussed by which Mg2+ changes the properties of the chloroplast envelope and thus secondarily induces the observed effects.
Notizen: Isoflavonoid Phytoalexins of Parochetus communis and Factorovskya aschersoniana
Authors: Ingham John L.
Published: August 2018

Medicarpin has been isolated as a phytoalexin from the fungus-inoculated leaflets of Parochetus communis and Fac­torovskya aschersoniana; a second isoflavonoid derivative, vestitol, is also produced by F. aschersoniana. Some taxono­mic aspects of phytoalexin formation by the title species are briefly discussed.
Immobilisierung von Adenosinacetalen mit variablem Alkylidenrest — die Funktion des Spacers bei enzymatischer Desaminierung / Immobilization of Adenosine-Acetals with Variable Alkylidene Residues — the Function of the Spacer during Enzymatic Deamination —
Authors: Seela Frank , Ott Johann , Rosemeyer Helmut
Published: August 2018

Acetalation of the cis-diol moiety of adenosine or inosine with aliphatic ketoesters of different chain lengths leads to alkylidene derivatives of the nucleosides, which differ in the number of methylene groups in the hydrocarbon chain. By alkaline hydrolysis of the ester group in 1a - c or 3a - c the corresponding acids 2a - c and 4a - c have been prepared.

The configuration of the new chiral centres has been determined as R.

Enzymatic deamination of the alkylidene derivatives of adenosine leads to the inosine compounds. The rate of deamination reaction is raised by an increasing number of methylene groups in the alkylidene residues or by use of the esters instead of the acids.

The alkylidene derivatives of adenosine were coupled with 6-aminohexylagarose yielding polymers with adenosine as ligands.

No enzymatic deamination of the polymer with the shortest spacer was observed. The polymers with the longer spacers were converted to the corresponding inosine derivatives. The velocity of the deamination reaction was raised by an increasing spacer length.
Inhibitors of Photosynthetic Electron Transport. The Properties of Diazidodialkylbenzoquinones
Authors: Bayley Hagan
Published: August 2018

The potential photoaffinity reagents 2,5-diazido-3-methyl-6-isopropyl-1,4-benzoquinone (DAZMIB) and 2,5-diazido-3,6-dimethyl-1,4-benzoquinone (DAZDMQ), which are analogs of the well-known inhibitor 2,5-dibromo-3-methyl-6-isopropyl-1,4-benzoquinone (DBMIB), block photosynthetic electron transport in spinach chloroplasts. On irradiation, at relatively high concentrations, DAZMIB inhibits electron flow irrevers­ibly. However, when [3H] DAZDMQ was photolyzed with chloroplasts, no labeling of the membrane proteins was ob­ served. Rearrangements of the nitrenes derived from the oxidized or reduced azidoquinones that might account for this behaviour are discussed.
Differences in Hydrolysis and Binding of Homologous Juvenile Hormones in Locusta migratoria Hemolymph
Authors: Peter Martin G. , Gunawan Sonny , Gellissen Gerd , Emmerich Hans
Published: August 2018

Male Locusta hemolymph contains JH-esterase(s) and a JH-carrier protein with high affinity and low capacity that both interact enantioselectively with juvenile hormones. Exposure of race-mic JH-I and JH-III results in preferential hydrolysis of the naturally configurated enantiomer of JH-I but the unnaturally configurated enantiomer of JH-III. The JH-carrier protein has a remark­ able specificity for the natural enantiomer of JH-III but discriminates only weakly between enantiomers of JH-I. This observation indicates a protective function of the JH-specific carrier protein for JH-III but not for JH-I. A third major protein, the diglyceride carrier lipoprotein (DGCL), shows no stereoselectivity at all.
High Performance Liquid Chromatography of Anthocyanidins as a New Approach to Study Flower Pigment Genetics
Authors: Akavia Naaman , Strack Dieter
Published: August 2018

The described method allows rapid screening and accurate quantification of anthocyanidins with the aid of HPLC. Using a linear gradient in 40 m in from 20 to 40% of solvent B (1.5% phosphoric acid -20% acetic acid - 25% acetonitrile) in solvent A (1.5% phosphoric acid) + B on LiChrosorb RP-8 the common six anthocyanidins delphinidin, cyanidin, petunidin, pelargonidin, peonidin, and malvidin were resolved within 40 min. It is demonstrated that acetonitrile is superior to other solvents in resolving methoxylated phenolic compounds. The application of the described method is shown with Gladiolus petals in studies of flower pigment genetics.
Substituted p-Benzoquinones Having High Electron Affinity as Photosystem II Electron Acceptors
Authors: Daniell H. , Kulandaivelu G. , Singh U. Chandra
Published: August 2018

Substituted Benzoquinones, Photosystem II Acceptors Benzoquinones (BQ) substituted with alkyl or alkoxy groups 2,5-dimethoxy-3,6-dichloro-p-benzoquinone (DCDMQ), 2,3,5,6-tetramethoxy-p-benzoquinone (TMQ) have been tested for their electron affinity and site of action in the photosynthetic electron transport chain in whole cells and chloroplasts. Both the substituted compounds were found to be good electron acceptors of photosystem II. DCDMQ showed higher electron affinity than BQ as demonstrated by its two fold stimulation of O2 evolution in chloroplasts and efficiency in quenching DCMU fluorescence. TMQ on the other hand showed low electron affinity.