bluuebunny/crossref_metadata_2025_split huggingface dataset:
Symmetric and Asymmetric Bilayers of Retinal
Authors: Rich Marvin , Brody Seymour Steven 
Published: August 2018

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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.
“Prebumps”: Evidence for Double-H its at Functional Subunits in a Rhabdomeric Photoreceptor
Authors: Hamdorf K. , Kirschfeld K. 
Published: August 2018

Abstract
In fly photoreceptors the latency of “bumps” due to single photon absorption is in the mean 60-70 (± 20) ms (10 °C). With increasing stimulus intensities first the amplitude of the receptor potential increases without shortening of the latency; with still higher intensities the latency is reduced also. The first reduction occurs if neighboured microvilli are simultaneously hit by one light quantum each or if individual microvilli are hit by two quanta. Such “double hits” lead to a discrete reduction in latency which is manifested as a “prebump”.
Phytoalexins from Dolichos biflorus
Authors: Keen Noel T. , Ingham John L. 
Published: August 2018

Abstract
Genistein, 2′-hydroxygenistein, dalbergioidin, kievitone and phaseollidin have been found to accumulate in leaves and stems of Dolichos biflorus (horsegram) following inoculation with the non-pathogens Pseudomonas pisi and Phytophthora megasperma f. sp. glycinea, respectively. They are accompanied by isoferreirin (5,7,4′-trihydroxy-2′-methoxyisoflavanone), a compound not previously reported as a natural product. Coumestrol and psoralidin occur constitutively in Dolichos leaves and stems.
Membrane Fusion and Deformation of Red Blood Cells by Electric Fields
Authors: Scheurich Peter , Zimmermann Ulrich , Mischel Maja , Lamprecht Ingolf 
Published: August 2018

Abstract
Human red blood cells suspended in a slightly hypotonic solution of low electric conductivity were exposed to an inhomogeneous and alternating electric field (sine wave, 30 V peak-to-peak value, electrode distance 120 μm, 0.5 to 2 MHz). Due to the dielectrophoretic effect the cells align parallel to the field lines under the formation of pearl chains. At high voltages (10 V amplitude) membrane fusion is observed between the adhered red blood cells in the pearl chains, whereby the chains become attached to the electrodes. In contrast to the pearl chains observed at voltages of up to 5 V amplitude the resulting fused and uniform aggregates which exhibit no recognisable individual cells under the light microscope, remain stable, even after the alternating electric field has been switched off or after haemolysis in response to osmotic shock. The fused aggregates are highly elastic. If the field strength of the applied alternating electric field is further increased they are stretched in the direction of the opposite electrode. Frequently, bridges are formed between the two electrodes. The uniform bridges remain stable for some time even in the absence of an electric field. The possibility of cell fusion and its initiation by electrical breakdown of the cell membranes are discussed.
Paramagnetic Species in β-Thalassemic Sera: an ESR Study
Authors: Cannistraro S. , Indovina P. L. , Sportelli L. 
Published: August 2018

Abstract
Homozygous beta thalassemic sera show an electron spin resonance (ESR) signal at g ≃ 6 which is not present in normal and heterozygous sera. The signal arises from high spin heme groups exhibiting a departure from tetragonal symmetry toward rhombic. Binding by a serum protein is very likely responsible for such a distortion. In contrast with other authors’ findings, we report that heme-human albumin complex shows a similar rhombic distortion.
The observed ESR signal at g ≃ 6 is then attributed to this complex.