bluuebunny/crossref_metadata_2025_split huggingface dataset:
Epicuticular Leaf Flavonoids from Eucalyptus Species and from Kalmia latifolia
Authors: Wollenweber Eckhard , Kohorst Gisela 
Published: August 2018

Abstract
In young plants of Eucalyptus globulus the leaves are covered with a whitish epicuticular layer. This leaf wax contains small amounts of C-methylated flavones as aglycones. A novel flavone has now been identified as 5,4′-dihydroxy, 7-methoxy, 6-methyl-flavone (8-desmethyl-sideroxylin). Another minor external flavone is chrysin. On leaves of E. sieberi the flavanone pinocembrin could be detected. It is shown that the four C-methylated flavones, eucalyptin, 8-desmethyl-eucalyptin, sideroxylin, and 8-desmethyl-sideroxylin are present in the leaf wax of 8 species analyzed. The same flavones are present on leaves of Kalmia latifolia.
Studies on the Zn2+/Co2+ Exchange with Acylamino Acid Amidohydrolase from Pig Kidney
Authors: Kumpe Eckhard , Löffler Hans-Gerhard , Schneider Friedhelm 
Published: August 2018

Abstract
The kinetics of inactivation of the Zn2+-metalloenzyme acyl-amino acid amido hydrolase by chelating ligands were studied. The rate of inactivation by 1,10-phenanthroline is enhanced by histidine and inhibited in the presence of phenyl-alanine. Removal of the metal ion increases the heat stability and decreases the pH stability of the enzyme. Reactivation of the inactive metal free enzyme is possible with Zn2+ and Co2+. Titration of the metal free protein with a Co2+/nitrilotriacetate metal buffer revealed a dissociation constant of about 10-7 ᴍ for the Co2+ enzyme (Zn2+ enzyme = 10-10ᴍ). The Co2+ substituted enzyme is less stable than the Zn2+ enzyme. Histinide and phenlalanine protect the Co2+ enzyme against inactivation by 1,10-phenanthroline.
Different Protein-Lipid Interaction in Human Red Blood Cell Membrane of Rh Positive and Rh Negative Blood Compared with Rhnull
Authors: Dorn-Zachertz Dietmar , Zimmer Guido 
Published: August 2018

Abstract
1-anilino-naphthalene-8 -sulfonate (ANS) fluorescence measurements have revealed that red blood cell membrane of the Rhnull type undergoes a transition at about 16 °C. In contrast, viscosity measurements of the extracted membrane lipids showed the usually observed transition at about 18 °C.
Lower values of titratable sulfhydryl (SH) groups were observed in Rhnull membrane using 5,5′-dithiobis-(2-nitro-benzoic-acid) (Nbs2). In contrast, disulfide bonds in Rhnull membrane were estimated to be about 3 times the value of the controls.
Spin labeling experiments using 2-(3-carboxypropyl)-4, 4 dimethyl-2-tridecyl 3-oxazolidinyl-oxyl were carried out with phospholipase A2 modified membranes. The mobile part of the spectra was significantly increased on the Rhnull membrane.
In the presence of ᴅ-glucose, infrared spectrometry showed a larger reduction of the intensity of the POO-band in Rhnull membrane.
In contrast to controls, binding of the reagent diethylpyrocarbonate resulted in no significant changes of the Rhnull membrane as determined by electron spin resonance (ESR) measurements.
ᴅ-glucose transport activity was found to be at the upper level of a group of Rh positive and Rh negative persons.
It is suggested that the intensity of the polar protein-lipid interaction is reduced in Rhnull membrane.
Nitrate Photo-Assimilation by the Phototrophic Bacterium Rhodopseudomonas capsulata E1F1
Authors: Castillo F. , Caballero F. J. , Cárdenas J. 
Published: August 2018

Abstract
Rhodopseudomonas capsulata E1F1 bacteria photo-assimilated nitrate under anaerobic conditions, but were incapable of reducing it in the dark. The bacteria utilized dissolved N2 as nitrogen source, but the growth in the presence of nitrate was 5-fold higher. Nitrite was excreted to the medium, but not stoichiometrically with respect to nitrate consumption. Nitrate reductase is particulate and used reduced viologens or flavins as electron donors for nitrate reduction. The enzyme was inhibited in vitro by KCN, NaN3, dithioerythritol and mercurials. Ammonia and other sources of reduced nitrogen repressed nitrate reductase synthesis.
Electron Transport to Assimilatory Nitrate Reductase in A zotobacter vinelandii
Authors: Bothe Hermann , Häger Klaus-Peter 
Published: August 2018

Abstract
Assimilatory nitrate reductase was particle-bound in extracts from Azotobacter vinelandii. Nitrate reduction by particle fractions was dependent on NADPH and a particle-bound electron carrier. When the enzyme was solubilized from the particles by treatment with detergents, the particle-bound electron carrier could be substituted by ferredoxin or flavodoxin. Flavodoxin reduced at the expense of photoreduced deazaflavin was much more efficient than ferredoxin in transferring electrons to nitrate reductase. The addition of both ferredoxin and flavodoxin to the assays with photoreduced deazaflavin gave additive effects. With the solubilized enzyme, NADPH only poorly supported nitrate reduction even after the addition of electron carriers. The experiments indicate that A. vinelandii utilizes an electron transport chain between NADPH and nitrate reductase with some properties similar to those described for the generation of reductants to nitrogenase.
Application of Liquid Chromatography to a Study on 4-Coumarate: Coenzyme A Ligase Activity
Authors: Knogge Wolfgang , Weissenböck Gottfried , Strack Dieter 
Published: August 2018

This report describes the separation of components from a 4-coumarate: CoA ligase assay by means of liquid chromatography. With the aid of polyamide column chromatography it is possible to enrich and isolate chromatographically and UV spectroscopically pure p-coumaroyl- CoA using as a solvent 0.01% NH4OH in methanol subsequent to water and methanol alone.
High performance liquid chromatography on octadecylsilane-bonded silica stationary phase allows a discontinuous determination of ligase activity. All components - ATP, Coenzyme A, pcoumaric acid, and the products AMP and p-coumaroyl-CoA - can be separated and accurately quantified within 20 min using a water-acetonitrile gradient, containing 1% phosphoric acid. The presented HPLC method may be used to affirm the accuracy of optical tests
Induction of Phytoalexin Synthesis in Soybean. Structure and Reactions of Naturally Occurring and Enzymatically Prepared Prenylated Pterocarpans from Elicitor-Treated Cotyledons and Cell Cultures of Soybean
Authors: Zähringer U. , Schaller E. , Grisebach H. 
Published: August 2018

Using HPLC on a partisil column (5 μm) it was possible to separate two reaction products from an enzyme incubation of dimethylallylpyrophosphate and 3,6a,9-trihydtoxypterocarpan with a particulate fraction from elicitor-treated soybean cotyledons (Harosoy 63) or soybean cell cultures. These two products were identified by MS and 1H-NMR analysis as 2- and 4-dimethylallyltrihydroxypterocarpan. Both compounds also occur as natural products in elicitor-treated soybean cotyledons and to a smaller extent in soybean cell cultures. Introduction of the dimethylallyl substituent into trihydroxypterocarpan increases the fungitoxicity against Cladosporium cucumerinum.
Upon treatment with alkali, solutions of 3,6a,9-trihydroxypterocarpans turn to an intense red colour with λmax around 530 nm. One of the products from 2-DMA-THP could be isolated by reversed phase HPLC. According to its mass spectrum a quinoid structure is proposed for this red pigment
The Coloration of Gladiolus I. Survey of Anthocyanins in Petals of Gladiolus
Authors: Akavia Naaman , Strack Dieter , Cohen Avner 
Published: August 2018

Abstract
The six common anthocyanidins found in Gladiolus petals occur in four types of glycosilation: 3-glucoside, 3-rhamnoglucoside, 3,5-diglucoside, and 3-rhamnoglucoside-5-glucoside. The six monoglucosides appear in minute quantities, whereas any of the other 18 anthocyanins can serve as the major contributor to the coloration of Gladiolus petals. In high performance liquid chromatographic analyses of petal pigment composition of nine cultivars, it was found that the anthocyanins are grouped on the basis of the aglycon substitution. Thus, pelargonidin appears by itself (group I), cyanidin and peonidin constitute group II, and delphinidin, petunidin, and malvidin group III.
⊿2,10-Phytadienol as Esterifying Alcohol of Bacteriochlorophyll b from Ectothiorhodospira halochloris
Authors: Steiner R. , Schäfer W. , Bios I. , Wieschhoff H. , Scheer H. 
Published: August 2018

Abstract
Bacteriochlorophyll b (bchl b) has been isolated from the halophilic photosynthetic bacterium, Ectothiorhodospira halochloris. The pigment and a series of derivatives thereof are different from Bchl b from Rhodopseudomonas viriais by HPLC analysis, but similar by uv-vis spectroscopy.
The chromatographic difference originates in different esterifying alcohols in the two pigments. The one from Rp. viridis (Bchl bp) is esterified with ⊿2-phytaenol (phytol), that from E. halochloris (Bchl b⊿2,10) with ⊿2,10-phytadienol. The structure of the latter has been established by isolation of the alcohol from the purified pigment, followed by (i) gaschromatography-mass spectroscopy and (ii) ozonolysis and dinitrophenylhydrazon-formation of the cleavage products, which were identified by gaschromatography-mass spectroscopy as 6-methyl-heptan-2-one, and 4-methyl-nona-1,8-dione.
Inhibition of Oogenesis and Ovarian Ecdysteroid Synthesis by Azadirachtin in Locusta migratoria migratorioides (R. & F.)
Authors: Rembold Heinz , Sieber Klaus-Peter 
Published: August 2018

Abstract
The sterilizing effect of azadirachtin, an insect growth regulator from the neem tree, Azadirachta indica A. Juss, was tested with mature females of Locusta migratoria. After a single injection of 10 μg into females between 2 and 13 days after emergence, about 60% died during the following four days and all lost weight in the range of about 50%. If the compound was injected into animals of an age between 2 and 10 days, no maturation of the terminal oocytes could be observed. Injection at an age between 10 and 13 days after adult emergence resulted in ovaries which contained almost mature oocytes. Most of the treated locusts had no oviposition and only traces of ecdysteroids were present in their ovaries, as quantified by radioimmunoassay. The inhibition of oogenesis and of ovarian ecdysteroid synthesis by azadirachtin is discussed on the basis of its interference with the neuroendocrine control of hormone synthesis.
Courtship-Like Tracking Behaviour in Wild-Type Female Drosophila melanogaster
Authors: Cook Robert 
Published: August 2018

Abstract
Both male and female Drosophila melanogaster possess systems which enable them to track other walking flies visually. Males use this system predominantly in courtship; females, when of sufficient age but still unmated, have been observed to track other flies, at rates of up to 18 bouts per hour. This behaviour is most conveniently studied in groups of females. Although similar to the courtship tracking of males, fem ale/female tracking lacks the “circling” component of courtship. The data suggest a functional relationship of female/female tracking to reproductive behaviour, although none has yet been identified. Bouts of tracking by females are most frequently terminated by the following female, especially when the target female remains motionless. Comparison of the tracking parameters of males and females has revealed differences in the velocity and pathlength of tracking bouts, and in the position of the fly with respect to the target. Males of Canton and Kapelle strains differ in the translatory component of their courtship tracking, but such a difference was not evident between females of these strains. Furthermore, tracking females do not allow their distance to the target to rise to that permissible in males, which suggests some sex-specificity in a part of the control system for tracking.
Lymphocyte Chalone from Calf Thymus: Problems of Large Scale Extraction and Assay
Authors: Maschler Reinhard , Maurer H. Rainer 
Published: August 2018

Abstract
Large scale extraction and assay of the lymphocyte chalone (LC), the natural lymphocyte proliferation inhibitor, require optimized, reproducible and standardizable methods. To this end we compared the effects on LC yield of storing thymus at different temperatures after collection from calves: Both quick freezing on solid CO2 and slow freezing at -5 0 °C led to a 30% loss of LC yield relative to that from unfrozen tissue kept at 0°C . Moreover we found that the apparent decrease or total loss of LC activity upon storage of a purified LC fraction may result from an occasional lack of LC-responsiveness of human blood lymphocytes depending on the donor's physiological state, in spite of normal PHA reactivity. This suggested the use of LC-responsive, cryopreserved lymphocytes, the advantages of which are documented and discussed in detail.
Interaction of Phloretin with the Human Red Cell Membrane and Membrane Lipids: Evidence from Infrared, Raman and ESR Spectroscopy
Authors: Zimmer Guido , Günther Herbert O. , Schmidt Hartmut 
Published: August 2018

Abstract
Membrane-Phloretin Interaction, Infrared Raman, ESR Spectroscopy The transport inhibitor phloretin was bound to human red cell membrane and the concomitant structural changes were observed by spectroscopic methods. By the spin labeling method a decrease in fluidity of the membrane was found at 1 and 10 |iM concentrations of the reagent. This result was obtained with the 2-(3-Carboxypropyl)-4,4-dimethyl-2-tridecyl-3-oxazolidinyloxyl, and the 2-(14-Carboxytetradecyl)-2-ethyl-4,4-dimethyl-3-oxazolidinyloxyl lipid spin labels. Infrared spectroscopy of modified membranes revealed an intensity increase of the POO~ band at about 1250 cm-1. Moreover, a shift of the peak at 1050 cm -1 to 1100 cm-1 was observed in the presence of phloretin. Raman spectroscopy of the membranes did not contradict the results found with infrared and ESR spectroscopy: In the phloretin modified membrane we observed a lack of the band at 1085 cm-1, which leads to suggest that the POO" and/or C-C regions are less fluid. Changes of the extracted red cell membrane lipids were less characteristic, and the results differed from those found in red cell membrane.
Chemical Synthesis of α-Formylphenylacetic Acid, the Postulated Precursor of Tropic Acid
Authors: Gross Georg G. , Koelen Karl J. , Müller Angelika , Schmidtberg Günter 
Published: August 2018

Abstract
a-Formylphenylacetic Acid, Phenylmalonic Semialdehyde, Tropic Acid Biosynthesis a-Formylphenylacetic acid, the postulated immediate precursor of tropic acid, has been synthesized by deacetalization of a-diethoxymethylphenylacetic acid in the presence of silica gel. The compound was reasonably stable in organic solution. In aqueous media, however, a pronounced lability of this semialdehyde was observed at various pH-values (t/2 = 4.5 min at pH 7.4). It is thus very unlikely that this compound can be employed successfully in biosynthetic studies.
Genetic Control of Chalcone Synthase Activity in Flowers of Matthiola incana R.Br
Authors: Spribille R. , Forkmann G. 
Published: August 2018

Abstract
Chalcone synthase activity was demonstrated in enzyme preparations from flowers of defined genotypes of Matthiola incana (stock). The product formed from 4-coumaroyl-CoA and malonyl-CoA was naringenin and not the isomeric chalcone, because chalcone isomerase was also present in the reaction mixture. Chalcone synthase activity could be detected only in flower extracts of genotypes with wild-type alleles at the locus f Thus, the interruption of the anthocyanin pathway in white flowering lines with recessive alleles (ff) of this gene is clearly due to a lack of this enzyme activity. Independent on the genetic state of the locus b which controls the formation of pelargonidin or cyanidin, respectively, in the flowers, 4-coumaroyl-CoA was the only suitable substrate for the condensation reaction.
Properties and Subcellular Localization of ʟ-Alanine: Aldehyde Aminotransferase: Concept of an Ubiquitous Plant Enzyme Involved in Secondary Metabolism
Authors: Wink Coralie , Hartmann Thomas 
Published: August 2018

Abstract
L-Alanine: aldehyde aminotransferase occurs ubiquitously in higher plants. The enzyme catalyzes the reaction: L-alanine + monoaldehyde -> monoamine + pyruvate; it is responsible for the formation of aliphatic plant amines and involved in the biosynthesis of hemlock alkaloids as shown by Roberts. A continuous coupled photometric test was developed to determine the low activities of the transaminase. The enzyme from the "amine-free" plant Spinacia oleracea was purified 77-fold and separated from other aminotransferases. A comparison of the Spinacia enzyme with that isolated from spadix-appendices of the amine-producing Arum maculatum during anthesis revealed very similar characteristics in pH-dependence, ATm-values for alanine and aliphatic aldehydes, and inhibition by 2-oxoacids. In contrast to the Spinacia enzyme the Arum aminotransferase is rapidly inactivated in the absence of pyridoxal-5'-phosphate. The enzymes of S. oleracea, A. maculatum and Mercurialis perennis are localized in mitochondria, but not in chloroplasts or peroxisomes. The results are discussed in relation to the function of alanine: aldehyde aminotransferase in secondary metabolism. It is suggested that some enzymes may be expressed in plants at low levels, even in the absence of any metabolic function.
The Inhibition of Photosynthetic Light Reactions by Halogenated Naphthoquinones
Authors: Pfister Klaus , Lichtenthaler Hartmut K. , Burger Günther , Musso Hans , Zahn Manuel 
Published: August 2018

Abstract
Halogenated naphthoquinones act as inhibitors of photosynthetic electron flow. I50 concentra­ tion for inhibition of methylviologen reduction were found to range between 2 × 10-5 m to 2 × 10-6 M. Comparing their effects on several partial reactions of electron flow, the inhibition site of the naphthoquinones was found to be at the reducing site of PS II. Studies of fluorescence transients in presence of halogenated naphthoquinones give further evidence for a site action similar to that of diuron and different to that of DBMIB. All naphthoquinones act as quenchers of chlorophyll fluorescence with pure chlorophyll a, and with much higher efficiency in green algae and chloroplasts. It is concluded, that the halogenated naphthoquinones act similar to PS II-inhibitors like diuron, but do not share a common binding site at the PS II-complex. Implications of a possible involvement of phylloquinone K 1 in photosynthetic electron transport are discussed. The synthesis of 2-chloro-as well as 2-bromo-3-isopropyl-1,4-naphthoquinone is described.
Site of Action of 2,5-Dimethoxy-3,6-Dichloro-p-Benzoquinone in the Photosynthetic Electron Transport Chain
Authors: Sarojini G. , Daniell H. 
Published: August 2018

Abstract
Electron Acceptors, Photosystem II, Quinones and Quinonediamines Dichlorodimethoxy-/?-benzoquinone (DCDMQ) was tested for its site of action in the photo­ synthetic electron transport chain. Hill reaction mediated by DCDMQ was insensitive to DBMIB (1 nm) but sensitive to DCMU, suggesting its site of action before plastoquinone but after Q -the primary electron acceptor of photosystem II. Extraction of freeze-dried chloroplasts with heptane and analyzing their capacity to photo-oxidize water using various Hill oxidants revealed that silicomolybdate (SiMO) and DCDMQ could effectively restore the activity. Diaminodurene (DAD) in the presence of ferricyanide could restore 40% of the activity. But ferricyanide alone failed to restore the ability to photo-oxidize water in heptane extracted chloroplasts. Similarly, N a2S 0 3 which is known to cause a bottleneck in the electron flow at plastoquinone affected the ferricyanide Hill reaction. Hill reactions mediated by SiMO and DCDMQ were insensitive to the addition of Na2SO3, suggesting that both these oxidants intercept electrons before plastoquinone. But 50% of the activity was lost when sulfite was added to the Hill reaction mediated by DADox. DNP-INT, melittin and picrylhydrazyl were recently introduced as photosystem II inhibitors inhibiting the electron flow between Q and the PQ pool. While DCBQ and DCDMQ Hill reactions were insensitive to DNP-INT, ferricyanide was highly sensitive. The quinonediamines TMPD and DADox showed 50% decrease in the electron transport rate, similar to heptane extracted or sulfite inhibited chloroplasts. Melittin increased the electron transport rate when ferricyanide or TMPD was the Hill oxidant, while DCBQ and DCDMQ reduction remained unaffected. However, DADox Hill reaction showed 50% inhibition in the presence of melittin. Picrylhydrazyl - which inhibits the electron flow between Q and the PQ pool - inhibited the Hill reaction of all the PS II electron acceptors except that of DCDMQ. It is possible that there is another site of intercepting electrons between Q and plastoquinone before the site where most of the quinonediamines accept electrons.
Evidence for a Transcarboxylase Reaction in Maize Chloroplast Extracts
Authors: Pan David , Tan Kim H. 
Published: August 2018

Abstract
The authors have suggested (Can. J. Bot. 49, 631 (1971) that the — COOH group of the C4-P carbonyl compound of the thermostable P-enolpyruvate acid carboxylase reaction may transcarboxylase with a pentose phosphate as ac­ ceptor. We now have considerable evidence supporting this consideration. In an assay system (0.8 ml) containing soni­ cated chloroplast extract in 0.1 m Tris-HCl, pH 6.3; and PEP, 0.1 |imol; Mg2+, 0.5 nmol; NADH, 0.25 nmol; sugar phosphate, 0.5 nmol. The amount of 14C 0 2 fixation is con­ siderably enhanced by either ribose-5-phosphate, fructose-1,6-bisphosphate or ribulose-l,5-bisphosphate in the pres­ ence of PEP. The products of the reaction include malate as a product of /?-carboxylation, and glycerate or 3-phosphate glycerate, their proportion being determined by the ac­ ceptor sugar phosphate. The results provide evidence for a "transcarboxylase" presented in the crude extract of Maize chloroplasts.
Location of Several Enzymes of ʟ-Arginine Catabolism in Evernia prunastri Thallus
Authors: Legaz Estrella , Vicente Carlos 
Published: August 2018

Abstract
Agmatine ureo: hydrolase, which produces both putres-cine and urea from agmatine, and urease, which hydrolyzes this urea, are highly restricted to the phycobiont cells in E. prunastri thallus. Arginase and L-arginine decarboxylase, which catabolize L-arginine, have a more extensive dis­ tribution between both symbiotic partners.
Incorporation of Chlorinated Anilines into Lignin
Authors: Trenck K. T. v. d. , Hunkier D. , Sandermann H. 
Published: August 2018

Abstract
Coniferyl Alcohol, Peroxidase, Lignin, 4-Chloroaniline, 3,4-Dichloroaniline Lignin was formed in vitro by the peroxidase/hydrogen peroxide mediated polymerization of coniferyl alcohol. In the presence of [14C]4-chloroaniline or [14C]3,4-dichloroaniline copolymeri­ zation occurred with incorporation rates of about 45 mol%. Co-elution of UV-absorbing material (reflecting lignin) and of incorporated radioactivity was observed on a calibrated column of Sephadex LH-60. This method indicated a broad molecular weight distribution of the copolymers with values of between about 20000 and 1000. Most of the copolymer products had apparent molecular weights near 1000.
The 1H-NMR and 13C-NMR spectra of the copolymers were compared with those of in vitro lignin. The copolymer spectra showed a relative increase in aromatic peaks and a relative decrease in most of the typical lignin peaks. Three peaks indicative of a new type of phenyl-propanoid side-chain structure were detected in the 'H-NMR and 13C-NMR spectra of the copolymers. The corresponding 1H-NMR chemical shift values were 4.75 ppm (a-C-H), 4.40 ppm (β-C-H) and 3.70/3.50 ppm (y-C-H2). The 13C-NMR chemical shift values were 56.9 ppm (a-C), 84.3 ppm (β-C) and 60.0 ppm (y-C). These peaks were attributed to a 3-aryl-3-anilino-2-aryloxy-propanol-1 structure in the copolymers by analysis of coupling patterns and by comparison with spectral reference data.
The NMR-results and experiments with catalase and inhibitors suggested that a major mechanism of copolymerization consisted of a nucleophilic addition of the anilines to the benzylic ar-carbon of lignol quinone-methide intermediates.