bluuebunny/crossref_metadata_2025_split huggingface dataset:
Residual Motion of Hemoglobin-Bound Spin Labels as a Probe for Protein Dynamics
Authors: Steinhoff Heinz-Jürgen , Lieutenant Klaus , Schhtter Jürgen 
Published: August 2018

Abstract
The residual motion of spin labels bound to cysteine β93 of methemoglobin and oxyhemoglobin has been analyzed as a function of temperature and hydration. The rotational diffusion of the whole protein molecule has been prevented or restricted by crystallization, lyophilization or by high viscosity of the solution. The residual motion of the labels is characterized by an angle of the limited motion cone and their rotational correlation time using computer simulations of the E PR spectra. Two types of motion can be separated due to different correlation times and different dependenceson temperature and hydration. One of these motional mechanisms can be shown to be determined by protein fluctuations. Correlation times of these fluctuations decrease from 2 × 10-8 at T = 220 K to 10-9 s at T = 300 K in the samples of high water concentration. Strong correlation between the properties of the hydration shell and these fluctuations are observed.
On the Probability of a Common Origin for tRNA and 5S rRNA1
Authors: Staves Mark P. , Lacey Jr. James C. 
Published: August 2018

Abstract
As part of a continuing study on the origin of genetic coding and the process of protein synthesis, we have compared sequences of a large number of transfer RNAs and several 5S ribosomal RNAs using automated routines. Transfer RNAs were found to exhibit a high degree of matching with 5S rRNA s. These matches are considered to be indicative of sequence homology, reflecting common ancestry of the two molecules. Other possible explanations for the matches (convergence, transfection) are discussed and found to be highly implausible. Matches are also found between 5S rRNA and the introns of yeast precursor tRNAs. Many matches extend from before the 3′ end to after the 5′ end of circularized 5S rRNA sequences. Data is presented which indicates a tandemly duplicated or circular molecule could have served as the precursor to both 5S rRNA and tRNA . A derivative of this molecule may have functioned as a universal translator before the evolution of the highly specialized tRNAs.
Conformational Study of Some Amino Acid Conjugates of Indol-3-yl-acetic Acid (IAA) by 1H-NOE-Difference Spectroscopy. Structure/Auxin Activity Relationships
Authors: Duddeck Helmut , Hiegemann Monika , Simeonov Mario F. , Kojic-Prodic Biserka , Nigovic Biljana , Magnus Volker 
Published: August 2018

Abstract
Amino Acid Conjugates The conform ation of the side chain of indol-3-yl-acetic acid conjugates with am ino acids (L-alanine, glycine, L-i-leucine, L-a-aminobutyric acid, DL-aspartic acid, DL-phenylalanine, and 6-am inovaleric acid) has been studied by 1H -NMR -NOE -difference spectroscopy. Com parison with the conform ation in the solid state is given in the light of structure-activity relationships.
Composition of Lipids of Piqui (Caryocar coriaceum Wittm.) Seed and Pulp Oil
Authors: Dresen Heidrun , Prasad R. B. N. , Gülz Paul-Gerhard 
Published: August 2018

Abstract
The lipid composition of Piqui (Caryocar coriaceum) seed oil and pulp oil was analyzed and found to contain triacylglycerols (95.1/95.3%) as major components followed by free fatty acids (1.7/1.6%), diacylglycerols (1.6/1.5%), squalene (0.3/0.3%) and monoacylglycerols (0.1/0.1%). Phospholipids were found only in seed oil (0.2%). They were identified as phosphatidylethanolamine and phosphatidylinositol. The sterol fraction (0.1/0.1%) contained stigmasterol and β-sito-sterol. In seed oil triacylglycerols the C-53 molecular species were dominated (52.8%) follow ed by C-55 (37.7%), C-57 (6.9%) and C-51 (2.6%) in minor quantities. In pulp oil triacylglycerols C-55 (51.7%) was predominant followed by C-53 (30.6%) and C-57 (17.7%). Palmitic (16:0) and oleic (18:1) acids were always the major fatty acids in both oils. In seed oil their quantities were nearly the same, whereas in pulp oil oleic acid was predominant. Composition of Lipids of Piqui (Caryocar coriaceum Wittm.)
The Lipoprotein and Peptidoglycan of Rhodobacter sphaeroides
Authors: Woitzik Daniela , Dierstein Roland , Weckesser Jürgen 
Published: August 2018

The lipoprotein-peptidoglycan complex (rigid layer) from Rhodobacter sphaeroides was isolated. Treatment of the complex with N.O-diacetyl-muramidase cleaved off from the rigid layer the lipoprotein moiety with covalently bound peptidoglycan-fragments. The lipoprotein with the bound fragments showed a broad single band (Mr about 19,000) on SDS-polyacrylamide gels and had an isoelectric point of about 5.6. There was no serological cross-reaction with the rigid layer of Escherichia coli K12. The lipid moiety of lipoprotein with residual amino acids (mainly Gly, Ser, Gly, Asp) was obtained by Pronase E treatment of the rigid layer and chloroform -methanol extraction. It was free from phosphate and contained amide- and esterbound 18:1 and esterbound 16:0 and 18:0.
The isolated peptidoglycan, after enzymatical cleavage from the lipoprotein, had a chemical composition indicating Aly-type structure. Comparable studies, performed with Rhodobacter capsulatus 37b4 resulted in essentially similar results for rigid layer, lipoprotein and peptidoglycan compositions.
Heuristic Approaches to Finding New Herbicides Active in the Chloroplast
Authors: Yoshida Shigeo 
Published: August 2018

Herbicides inhibiting the photosynthetic electron transport (PET) system may be an important research target to introduce a biorational approach, since accumulated knowledge of the biological system has already reached a satisfactory level for detail explanation of their behaviors.
Besides structural modification of the known herbicides, an effective molecular design of potent PET inhibitors can be arrived at through consideration of the function of PQ at D 1 protein. New PET-inhibitory structures may also be discovered in natural products. Those compounds should be modified for the installation of herbicidal potency, which might require chemical parameters additional to those of the optimized structures at the binding site.
Binding studies of the PET inhibitors are essential in this type of research since it is very difficult to understand their structure-activity correlation in cases when a minor structural modification causes a dramatic change in their attacking sites.
It is also necessary to devise quick and reliable assay methods for herbicide screening in order to get accurate information about the structural effects and with this strategy the bio-assay using cultured cells has been proven to be a useful tool of structure-activity studies to detect the herbicidal requisites in the structures of PET inhibitors.
Studies on Herbicide Binding in Photosystem II Membrane Fragments from Spinach
Authors: Fromme R. , Technische G. Renger 
Published: August 2018

Abstract
The mechanism of atrazine binding and its modification by Chelex-100-induced Ca2+ depletion and proteolytic degradation by trypsin, was analyzed in PS II membrane fragments from spinach. It was found:
1) Chelex-100 treatment leads in a comparatively slow process (t1/2 = 5 - 10 min) to Ca2+ re­ moval from a site that is characterized by a high affinity as reflected by KD values of the order of 10-7
M. The number of these binding sites was found to be almost one per PS II in samples washed twice with Ca2+ -free buffer.
2) Chelex-100 treatment does not affect the affinity of atrazine binding but increases the susceptibility to proteolytic attack by trypsin.
3) The electron transport activity is only slightly affected by Chelex-100 treatment.
4) The atrazine binding exhibits a rather small T-dependence within the physiological range of 7 °C to 27 °C.
The implications of these findings for herbicide binding are discussed.
Diphenyl Ether Herbicides, a Tool to Elucidate the Mechanism of Photophosphorylation
Authors: Huchzermeyer Bernhard , Löhr Andreas 
Published: August 2018

At least two different classes of ADP binding sites on chloroplast coupling factor are described in the literature. High-affinity sites are assumed to entail regulatory functions while low-affinity sites are involved in catalysis.
Diphenyl ether herbicides, acting as energy transfer inhibitors, interfere with nucleotide exchange on both categories of ADP binding sites. Their inhibitory potency varies depending on their substitution. We found that each diphenyl ether assayed revealed identical I50 values for inhibition of nucleotide interaction with both classes of binding sites.
We show here that diphenyl ether inhibition of energytransfer is primary based upon the interference with ADP binding to high-affinity binding sites. Thereby the control of proton permeability through the coupling factor complex is affected. Moreover, we found that the three β-subunits are not absolutely fixed in one conformational state: After covalently blocking the high-affinity site by an azido-label. a new high affinity state appeared on another β-subunit.
Epicuticular Waxes from Leaves of Maple (Acer pseudoplatanus L.)
Authors: Prasad R. B. N. , Gülz Paul-Gerhard 
Published: August 2018

Abstract
The epicuticular waxes from the leaves of maples (Acer pseudoplatanus L.) contained hydrocarbons (6.9%), wax esters (5.5%), aldehydes (38.1%), primary alcohols (10.2%) and fatty acids (17.1%). In addition to these common wax lipids, benzyl acyl esters (2.1%) and triterpenoids were also present. β-Sitosterol, β-amyrin and 24-methylene-cycloartenol were found in the form of acetates (14.4%). β-Amyrin was also present as free alcohol (4.9%) and esterified with long chain fatty acids (~ 0.7%).
Ascorbic Acid and Chlorophyll Content in Cell Cultures of Spruce ( Picea abies): Changes by Cell Culture Conditions and Air Pollutants
Authors: Messner Burkhard , Berndt Jürgen 
Published: August 2018

Abstract
Conifers contain ascorbic acid which is probably a protective against oxidative attacks. In yellow needles of damaged conifers the ascorbic acid content is increased, this suggests an induction by air pollutants and/or photooxidants of a protection mechanism in trees. To study this mechanism in more detail, a green cell suspension culture of spruce (Picea abies) has been established. These cells contain chlorophyll and have a photosynthetic capacity, but they need carbohydrates (sucrose) for growth and are thus photoheterotrophic. Their ascorbic acid content and its regulation depends on carbohydrates, the cells resemble healthy green needles in this respect; they appear to be qualified for studies on the induction of a defense mechanism. Treatment of these cells with SO2 (20 ppm, 4 days) ozone (1 ppm, 14 days) and vaporous H2O2 revealed a decrease of the ascorbic acid content and (to a lesser extent) also of chlorophyll. It is concluded that (photo-)oxidants obviously do not play such a dominant role in bleaching of needles as it is assumed. The increased ascorbic acid content found in needles of damaged conifers is probably not an induced protection mechanism against oxidants.
Superoxide Scavenging Properties of Flavonoids in a Non-Enzymic System
Authors: Huguet Ana I. , Máñez Salvador , Alcaraz María José 
Published: August 2018

Abstract
The superoxide anion scavenging activity of 38 flavonoids, some of them isolated from Side-ritis mugronensis, Sideritis javalambrensis and Cayaponia tayuya were investigated by measurement of their inhibition of nitroblue tetrazolium reduction. Isoorientin, orientin, amentoflavone, leucocyanidol, eriodictyol, datiscetin and robinetin behaved as potent scavengers and structure-activity relationships were established.
The SO4
·̄induced Oxidation of 2′-Deoxyuridine-5′-phosphate, Uridine-5′-phosphate and Thymidine-5′-phosphate. An ESR Study in Aqueous Solution
Authors: Hildenbrand Knut 
Published: August 2018

Abstract
Reactions of photolytically generated SO4
·̄ with 2′-deoxyuridine-5′-phosphate (5′-dUMP), uridine-5′-phosphate (5′-UMP) and thymidine-5′-phosphate (5′-dTMP) were studied by ESR spectroscopy in aqueous solution under anoxic conditions. From 5′-dUMP and 5′-UMP the 5′,5-cyclicphosphate-6-yl radicals 10 and 11 were generated (pH 2 -11) whereas from 5′-dTMP at pH 3 -8 the 5,6-dihydro-6-hydroxy-5-yl radical 14 and at pH 7 -1 1 the 5-methylene-2′-deoxyuridine-5′-phosphate radical 15 was produced. In the experiments with 5′-UMP in addition to radical 11 the signals of sugar radicals 12 and 13 were detected. It is assumed that the base radical cations act as intermediates in the SO4
·̄-induced radical reac­tions. The 5′-phosphate group adds intramolecularly to the C(5)−C(6) bond of the uraclilyl radical cation whereas the thymidyl radical cation of 5′-dTMP reacts with H2O at pH < 8 to yield the 6-OH-5yl adduct 14 deprotonates at pH > 7 thus forming the allyl-type radical 15. In 5′-UMP transfer of the radical site from the base to the sugar moiety competes with intramolecular phosphate addition.
Effect of ß-Carotene on Delayed Light Emission from Aggregated Chlorophyll
Authors: Yang Shan-Yuan , Brody S. S. 
Published: August 2018

Abstract
Delayed light emission (DLE) from aggregated chlorophyll is used to probe energy transfer between aggre­ gated chlorophyll and β-carotene. Preilluminated β-carotene when injected into a dark chamber containing aggregated chlorophyll, induces DLE from aggregated chlorophyll. If the dark chamber contains only monomeric chlorophyll, there is no DLE. The intensity of DLE is dependent on the time of illumination of β-carotene. The decay of energy stored by the carotene is not a first order process. The first half life is about 2 min, the next about 10 min
Structure Confirmation for an Unusual Flavanone from Encelia stenophylla
Authors: Iinuma M. , Tanaka T. , Mizuno M. , Wollenweber E. 
Published: August 2018

Abstract
A flavanone with 3′-OH as the sole B-ring substituent has been reported recently as a leaf and stem exudate constituent of Encelia stenophylla. The correctness of this unusual substitution is confirmed by synthesis of this flavanone.
Flavonol Glycosides from Paederia scandens var. mairei
Authors: Ishikura Nariyuki , Yang Zhi-qing , Yoshitama Kunijiro , Kurosawa Kazu 
Published: August 2018

Abstract
Four kaempferol glycosides and five quercetin glycosides have been isolated from a methanolic extract of Paederia scandens var. mairei leaves and stems, in which in addition four un­known glycosides of kaempferol and quercetin are present in a trace. Nine flavonol glycosides including a new glycoside quercetin 3-O-rutinoside-7-O-xylosylglucoside (paederinin) were identified by PC, HPLC, UV spectral and NMR studies.
n-Alkanes -Common Surface Constituents of Pollen from Gymno-and Angiosperms
Authors: Hagenberg Susanne , Wehling Klaus , Wiermann Rolf 
Published: August 2018

Abstract
The surface waxes of several gymnosperm and angiosperm pollen were separated into different lipid classes. n-Alkanes were found to be common constituents of these waxes. They appeared as a homologous series ranging from C20 to C33. The distribution patterns of n-alkanes from gymnosperm pollen displayed little variation whereas those of angiosperm pollen exhib­ited pronounced differences from one another. It is noteworthy that especially for the gymno­sperm species, homologues with even and odd numbers of carbons occurred in similar amounts.
Screening of Basidiomycetes and Ascomycetes for Plant Growth Regulating Substances. Introduction of the Gibberellic Acid Induced de-novo Synthesis of Hydrolytic Enzymes in Embryoless Seeds of Triticum aestivum as Test System
Authors: Hautzel Ralf , Anke Heidrun 
Published: August 2018

Abstract
A new test system for the detection of plant growth regulating activities was successfully employed. In a screening for inhibitors of the gibberellic acid controlled synthesis of hydrolytic enzymes in embryoless wheat seeds (Triticum aestivum) 160 cultures of ascomycetes and basi­diomycetes were tested. In the extracts of two cultures inhibitory activities were detected. From fermentations of a Hypholoma-species (basidiomycetes) 3,5-dichloro-4-methoxybenzyl alcohol was isolated as the active principle.
Galiellalactone and two other new phytotoxins were isolated from cultures of the ascomycete Galiella rufa. At concentrations of 50 μg/ml all four compounds inhibited the de-novo synthesis of α-amylases, proteases, and phosphatases. Further investigations on the mode of action revealed, that all four metabolites interfere with early steps of the biosynthetic path­ ways induced by gibberellic acids. In vivo, the germination of the seeds of several plants was inhibited by these compounds.
An Amperometric Study on the Time Constants of Oxygen Release in Thylakoids of Nicotiana tabacum and Oscillatoria chalybea
Authors: Schulder R. , Bader K. P. , Schmid G. H. 
Published: August 2018

Abstract
Measurement of photosynthetic oxygen evolution in tobacco chloroplasts and thylakoids of the filamentous cyanobacterium Oscillatoria chalybea by means of the “Three-Electrode-System”, described by Schmid and Thibault in 1979, yields half-rise times for the directly measured amperometric O2-signal of approximately 2 msec for tobacco chloroplasts and slightly more than 2 msec for thylakoids of Oscillatoria chalybea. An estimate of the possible contribution of the diffusion time required for oxygen to leave the thylakoid membrane (7.5 nm thickness) or the chloroplast (diameter 4 -5 μm) might bring the measured O2-release time below 1 msec in full agreement with measurements by Joliot et al. in 1966.
Further Isoflavonoids from White Lupin Roots
Authors: Tahara Satoshi , Shibaki Seiji , Ingham John L. , Mizutani Junya 
Published: August 2018

Abstract
Further investigation of the isoflavonoids in white lupin roots has revealed a new coumaronochromone with a 2-hydroxy-3-methyl-3-butenyl side chain (lupinalbin G), three new pyrano-isoflavones (lupinisoflavones K and L, and allolicoisoflavone B) and two new di-hydrofurano-isoflavones each with a 2,3-dihydroxy-3-methylbutyl substituent (lupinisoflavones M and N). The biogenetic pathways for these and other lupin isoflavones are briefly discussed.
Light-Dependent Sucrose Synthesis in Cell-Free (Reconstituted) Lysates of Evacuolated Mesophyll Protoplasts
Authors: Steingraber Manfred , Frohnmeyer Hanns , Hampp Rüdiger 
Published: August 2018

Abstract
Oat mesophyll protoplasts were evacuolated by centrifugation on a Percoll gradient and used as starting material for establishing a functional cell-free system. For this purpose evacuolated protoplasts were osmotically lysed. From the resulting homogenate a cytosolic fraction was obtained by silicon oil filtration. This fraction was used to dilute preparations of lysed evacu­olated protoplasts in order to reduce the number of organelles per volume cytosol. The latter was necessary to increase light-dependent oxygen evolution of the cell-free system. The result­ing kind of “reconstituted” system showed light-dependent sucrose formation (about 100 nmol (mg Chi)-1 · hr-1) with bicarbonate as the only substrate. As this property depends on a functional interaction of chloroplast and cytosolic reactions, this cell-free system appeared to perform essential steps of partitioning of CO2 between starch and sucrose. Addition of about 12 μm fructose 2 ,6 -bisphosphate, an inhibitor of fructose 1,6 -bisphosphatase and an activator of the PPi-dependent fructose 6 -phosphate phosphotransferase, caused sucrose degradation in the light. Thus, this cell-free system allows both the study of cytosolic enzyme activities under quasi in vivo conditions and the manipulation of cellular reaction sequences by plasma mem­brane-impermeable compounds.
Degradation of the D -l Protein Subunit of Photosystem II in Isolated Thylakoids by UV Light
Authors: Trebst Achim , Depka Brigitte 
Published: August 2018

Abstract
Thylakoid membranes from spinach were irradiated with UV light of 254 nm. Photosynthetic electron flow driven by photosystem II, but not by photosystem I is fully inactivated in about 2-5 min. Inactivation of electron flow is prevented by inhibitors of the QB site of both the DCMU and of the phenol type. UV light inactivates electron How both under anaerobic and aerobic conditions. This is in contrast to white light where fast inactivation occurs only under anaerobic conditions and where only inhibitors of the DCMU-type protect. Inactivation of electron flow by UV light is followed on a slower time scale by a specific degradation of thylakoid membrane proteins. As shown by immunoblotting the D-1 protein and to a smaller extent also the D-2 protein subunit - that together form the reaction center of photosystem II - are de- graded during UV light irradiation. The disappearance of these proteins occurs only under aerobic conditions. Both types of QB site inhibitors prevent the degradation of the two plasto-quinone-binding proteins. A degradation product of the D-l protein is observed at about 8 kDa size. The results are discussed in their relevance to rapid turnover and photoinhibition in vivo and to the topology of the quinone-binding site in the D-1 and D-2 protein.
Arsenic Depuration via the Tridacna Gill Membrane
Authors: Benson Andrew A. 
Published: August 2018

Abstract
Arsenate absorbed by zooxanthcllac in Tridacna species is converted to water-solubie arsen- ical products which accumulate in the kidney with concentrations up to 2%. Kinetic uptake experiments with radioarsenatc revealed rapid labeling in the algae and in the membrane lipids of the gills. Since the arsenic content of the gills is low. it is concluded that turnover is rapid and that the gills are the site of arsenic depuration in these clams. The amphipathic lipid nature of the gill arsenicals suggests membrane lipid mediation of the process.
Rhythmic Leaf Movements under Physical Loading of the Leaves
Authors: Pedersen M. , Johnsson A. , Herbjørnsen R. 
Published: August 2018

Abstract
The effect of physical loading on period and amplitude of the ultradian oscillating leaflets of Codariocalyx motorius (= Desmodium gyrans) and the circadian oscillating leaves of Oxalis regnellii was investigated. In Codariocalyx the leaflets were loaded with pieces of copper thread which were clamped to the leaflet. Weights of the loads varied from 3 to 12 mg, and a typical leaflet is 1.5 mg. In about 80% of the cases we recorded an increase of the period length due to the loading in the order of 10% (the period length is typically 3-4 min). The amplitude was lowered in all the cases, the magnitude depending on the size of the weight used. In most of the cases, when not too heavily loaded, both amplitude and period returned to (or close to) the previous value when the leaflets were unloaded. In Oxalis the leaves were loaded with metal clips fixed to the leaflets at the midrib position. All three leaflets on a stalk were loaded. The clips used weighed 390 ± 0.4. 640 ± 6 and 810 ± 4 mg respectively, and a typical leaflet is 91 ± 4 mg. For the heaviest weights at least, this resulted in a lowering of the amplitude, but the oscillations continued, and we could not observe any effect on the period of the rhythmic movements.
Electron Microscopic Study of the Polymyxin Treated Vibrio cholerae Cells
Authors: Mandal T. K. 
Published: August 2018

Abstract
Polymyxin B produces dose dependent changes in the surface topography of pathogenic Vibrio cholerae cells. The susceptibilities of various vibrio strains to PB are also studied through analytical techniques. Statistical analysis shows significant differences among the four vibrios with regard to their sensitivities to PB, the classical strains being the most sensitive. Treating the classical strain with subinhibitory concentration of PB. we observed with both SEM and TEM that the normal smooth surface of the cell envelope develops some protruded structures (blebs and crenations). Further the TEM study of the ultrathin sections reveal that the rod like projections are formed by protrusions of the outer-membrane of the cell wall.