bluuebunny/crossref_metadata_2025_split huggingface dataset:
Calcification of a Native Collagen Membrane
Authors: Wiedner Günther , Wilhelm Günther , Jureit G. , Bojadžijev Z. 
Published: August 2018

Abstract
Calcification, Collagen Membrane, Ca/P Ratio Dependence Spontaneous calcification of a membrane made of native collagen has been investigated. The method permits independent variation of calcium and phosphate concentrations. With increasing phosphate concentration the precipitation of calcium-phosphate on the collogen occurs at a conspicuously lower calcium concentration as with a number of other membranes.
Chalkone und Dihydrochalkone als Mehlbestandteile bei Farnen (Gattungen Cheilanthes und Notholaena ) / Chalcones and Dihydrochalcones as Constituents of Fern Farina (Genera Cheilanthes and Notholaena)
Authors: Wollenweber Eckhard 
Published: August 2018

Abstract
Gold-back ferns and silver-back ferns of the genus Pityrogramma are known to produce chalcones and dihydrochalcones, deposited as a farina on the under surface of their fronds. In Cheilanthes and Notholaen a mostly methy­lated flavones and flavonols are excreted, but some species are shown here to accumulate chalcones and dihydrochalcones, too. Their distribution within the genera and within the species is reported and discussed.
Phytoalexins of Hyacinth Bean (Lablab niger)
Authors: Ingham John L. 
Published: August 2018

Abstract
Seven isoflavonoid phytoalexins have been isolated from the fungus inoculated hypocotyls of Lablab niger and identified as the isoflavone 2′-hydroxygenistein, the isoflavanones dalbergioidin and kievitone, the pterocarpan phaseollidin and the isofiavans demethyivestitol, isovestitol and iaxifloran. Small quantities of the 2-arylbenzofuran, vignafuran, were also detected.
Protein-Catalyzed Isotopic Exchange Reaction between Cysteine and Sulfide in Spinach Leaves
Authors: Schmidt Ahlert 
Published: August 2018

Abstract
A protein has been isolated from spinach leaves which catalyzes the following isotopic exchange reaction: Cys-SH+H2
35S ↔ Cys-35SH + H2S . This enzyme has an pH-optimum above 9.0; its molecular weight has been estimated on a Sephadex-G-100 column to be around 64 000 daltons. During purification this exchange reaction activity follows cysteine synthase activity on DEAE-cellulose and Sephadex-G-100 column chromato­ graphy; however this enzyme fraction has not been purified to homogeneity to prove that both activities are catalyzed by the same protein.
The apparent Km for a) H2S has been determined to be 0.86 mM using cysteine as substrate and 0.6 mM using O-acetylserine as substrate; b) for cysteine was found to be 3.3 mM; and c) for O-acetylserine to be 3.3 mM. For catalysis no metal ion is required and the reaction proceeds without addition of pyridoxalphosphat. This exchange reaction might prove to be a simple method to prepare labelled cysteine from non-labelled cysteine and labelled H2S. The exchange reaction was found too in Chlorella pyrenoidosa and in Rhodospirillum rubrum.
Temperature Dependent Conformation Changes of Ribulose-1,5-bisphosphate Carboxylase Studied by the Use of 1-Anilino-8-naphthalene Sulfonate
Authors: Wildner Günter F. , Henkel Jürgen 
Published: August 2018

Abstract
The influence of temperature on the structure and enzyme activity of ribulose-1,5-bisphosphate carboxylase, isolated from Euglena gracilis cells, was studied. Freezing of the purified ribulose-1,5-bisphosphate carboxylase preparation causes a severe loss of enzyme activity, which can be restored again by incubation of the enzyme molecules at higher temperatures (50 °C). The titration of both enzyme samples with the fluorescence probe 1-anilino-8-naphthalene sulfonate (ANS) re­vealed an increase of the fluorescence emission of the low temperature form of the enzyme. Two different enzyme conformations can be assumed which differ in the number of binding sites for ANS and Vmax values for the carboxylase reaction but show similar binding constants for ANS and the apparent Km values for C02 .
Regulation and Characterization of L-Serine: Pyruvate Aminotransferase in Rat Liver Cytosol and Mitochondria
Authors: Hoshino Jiro , Kühne Uta , Filjak Branka , Kröger Hans 
Published: August 2018

Abstract
Distribution of rat liver serine: pyruvate aminotransferase between cytosol and mitochondria varies considerably with the dietary and hormonal state of animals. Feeding a high-protein diet or fasting the animals results in an increase in the enzyme activity of both fractions but more marked in the mitochondrial fraction. A low-protein diet exerts the reverse effect. A single administration of dibutyryl cyclic AMP causes a rapid elevation of the enzyme activity in both fractions, which is effectively prevented by cycloheximide, actinomycin D and cortisone. The activity in mitochondria increases with a lag of 2 h following injection of the nucleotide inducer, in contrast to the cytosol enzyme, which increases without any lag. Gel filtration and DEAE cellulose chromatography of the enzyme from both fractions revealed the similar pattern and some kinetic constants of these two types of the enzyme were not significantly different from each other. These results indicate that rat liver serine: pyruvate aminotransferase is synthesized in the extra-mitochondrial site and transfered to mitochondria.
Localization and Function of Cytochrome f in the Thylakoid Membrane
Authors: Schmid Georg H. , Radunz Alfons , Menke Wilhelm 
Published: August 2018

Abstract
A monospecific antiserum to cytochrome f agglutinates stroma-free swellable chloroplasts from tobacco and Antirrhinum. Consequently, antigenic determinants towards which the antiserum is directed are located in the outer surface of the thylakoid membrane. The antiserum inhibits linear photosynthetic electron transport. Just as described earlier for the antiserum to polypeptide 11000 this inhibition develops in the course of the light reaction. Ultrasonication in the presence of anti­ serum abolishes the light requirement and the maximal inhibition of the electron transport reaction is immediately observed. Electron transport in chloroplasts from a tobacco mutant which ex­ hibits only photosystem I-reactions is also inhibited by the antiserum. No time lag in the light for the onset of inhibition is observed with these chloroplasts. As chloroplasts of this mutant have only single unfolded thylakoids it appears that light might preponderantly open up partitions. If the light effect is interpreted in this way, cytochrome f should be located in the partition regions but nevertheless in the outer surface of the thylakoid membrane. However, a rearrangement of molecules in the membrane in the light by which the accessibility of cytochrome f is changed can­ not be excluded. The inhibition of linear electron transport by the antiserum is approximately 50 per cent and can only be increased to 75% upon the addition of antibodies to plastocyanin. The inhibition by the antiserum to cytochrome f as well as the combined inhibition by the antisera to cytochrome f and plastocyanin can be by-passed by DCPiP. It appears that cytochrome f and plastocyanin cannot be connected in series in the electron transport chain but are both closely associated in the thylakoid membrane.
PMS-mediated cyclic photophosphorylation in chloroplasts from wild type tobacco and the tobacco mutant NC95 is only inhibited if the chloroplasts are sonicated in the presence of anti­ serum. If one disregards, that ultrasonication might cause reaction artifacts, it is thinkable that the cytochrome f, involved in the PMS-mediated cyclic photophosphorylation reaction, might be located inside the membrane.
Elektronenmikroskopische Untersuchungen am Geruchsorgan von Ophicephalus ( Channa) obscurus GUENTHER, 1861 (Teleostei, Ophicephalidae) / Electron Microscopical Studies of Olfactory Organ of Ophicephalus (Channa) obscurus GUENTHER, 1861 (Teleostei, Ophicephalidae)
Authors: Schulte Erhard , Riehl Rüdiger 
Published: August 2018

Abstract
The regio olfactoria of Ophicephalus was studied by transmission electron microscopy. Two types of receptor cells were found: ciliary receptor cells and microvillous receptor cells. Both of these types represent primary sensory cells. So one can regard the light microscopical findings of Kapoor and Ojha as disproved.
Studies on the Retention of CF1 with or without Induced ATPase Activity by Pyrophosphate Treated Thylakoids and Its Relation to the Regeneration of Photophosphorylation
Authors: Schopf R. , Harnischfeger G. 
Published: August 2018

Abstract
The reconstitution of chloroplast coupling factor 1 (CF1) into thylakoid membranes was investigated by the fluorescence of the covalently attached label fluorescamine. In contrast to a func­tional regeneration of ATP synthesis, a rebinding of CF1 was observed regardless if the protein was in its native, purified state or had been activated for ATPase activity by heat, dithiothreitol (DTT) or trypsin treatment. The reintegration of CF1 into the thylakoid membrane was estimated to be almost quantitative.
Since the label binds covalently and irreversibly to free NH2-groups, its effects on the various functional parameters were investigated. Blocking of NH2 groups leads to inhibition of ATPase activity in isolated CF1 . Labeled factor used in a reconstitution experiment on the other hand, does still result in considerable regeneration of ATP formation.
Attaching the label to whole thylakoids leads to a differential effect on phosphorylation, which is inhibited, and the H+-uptake which seems largely unaffected. A differential effect is also observed on coupled and uncoupled electron transport.
The results are interpreted as evidence for an involvement of free NH2-groups in the mechanism of photophosphorylation.
A Method for the Purification of Large Quantities of Biologically Active Ribonucleic Acid Components from Cowpea Chlorotic Mottle Virus, a Multicomponent Plant Virus
Authors: Trim A. R. , Dawson J. R. O . , Dickerson P. E. , Sakai F. , Watts J. W. , Hirst W. , Cox R. A. 
Published: August 2018

Abstract
Cowpea chlorotic mottle virus RNA has been prepared in comparatively high yield (at least 50%) by a modified phenol extraction method. The preparation, which has high biological activity, has been resolved into four components by zonal centrifugation on a 15 - 40% (w/v) sucrose density gradient. The components obtained have been tested for biological activity against whole plants and plant protoplasts. Each of the two largest components RNA 1 and RNA 2 was by itself infective (50 - 90% of the specific infectivity of the whole genome) and produced virus-specific proteins (coat protein and P2) and RNAs (“RNA 3“ and “RNA 4”). Contamination by small proportions « 10 %) of neighbouring RNAs is presumed to be involved in this infectivity. The two smallest components were obtained in an almost pure form.
Changes in Gene Expression during Larval Development of Calliphora vicina Induced by Ecdysterone
Authors: Mascheck Peter , Scheller Klaus , Karlson Peter 
Published: August 2018

Abstract
The influence of the insect hormone ecdysterone on the composition of the RNA from the fat bodies of Calliphora larvae was investigated by hybridization experiments. DNA was iodinated in vitro with 125J. In saturation experiments, total RNA was hybridized to total DNA; under similar conditions, poly (A) RNA was hybridized to unique DNA sequences. RNA isolated from animals treated with ecdysterone exhibits a higher percentage of hybridization than a corresponding control RNA from the same developmental stage, a result even more prominent when poly (A) RNA was hybridized with unique DNA. It is concluded that ecdysterone induces the transcription of new unique DNA sequences.
The Spectral Sensitivity of the Ocelli of Calliploora (Diptera)
Authors: Kirschfeld K. , Lutz B. 
Published: August 2018

Abstract
The spectral sensitivity of the ocelli of Calliphora was determined by means of the electroretino-gram (ER G). Sensitivity is high in the spectral range from 340 to 450 nm ; with still increasing wavelengths it rapidly decreases. Analysis of the shape of the ERG resulting from stimuli of dif­ferent wavelengths, as well as experiments with selective chromatic adaptation, indicate that there is mainly one spectral mechanism contributing to the response.
Notizen: Isoflavonoid Phytoalexins from Leaves of Trifolium arvense
Authors: Ingham John L. , Dewick Paul M. 
Published: August 2018

Abstract
In response to fungal inoculation the leaves of Trifolium arvense accumulate the known isoflavonoid phytoalexins, medicarpin, maackiain, sativan, vestitol, and isovestitol. A previously undescribed isoflavan derivative (arvensan; 7,2′-dimethoxy-4′-hydroxyisoflavan) is also produced by this species. The identification and synthesis of arvensan is described.
The Orientation of the Electric Field Gradient Tensor in CO-Liganded Myoglobin
Authors: Parak F. , Thomanek U. F. , Bade D. , Wintergerst B. 
Published: August 2018

Abstract
The EFG-tensor at the position of the Fe-atom of CO-liganded sperm whale myoglobin has been investigated by nuclear γ-resonance absorption experiments on single crystals. In addition the tem­ perature dependence of the quadrupole splitting of the 14.4 keV level of the iron nucleus was measured. An unambiguous solution for the magnitude and the orientation of the field gradient tensor could only be obtained with the assumption that a C2-axis perpendicular to the haem plane is one principal axis of the electric field gradient tensor. Within this solution the electronic struc­ture of the iron is described by a singlet ground state with ηz = 0.75 and the largest EFG component perpendicular to the haem plane.
Glycerol Conformation and the Crystal Structure of Lipids. I. An Electron Diffraction Study of Tripalmitin and Conformationally Fixed Analogs
Authors: Dorset Douglas L. , Hancock Anthony J. 
Published: August 2018

Abstract
Transmission electron diffraction is used as a qualitative analytical probe of poly methylene chain packing in three conformationally-restricted analogs of tripalmitin derived from configurational isomers of cyclopentane-1,2,3-triol. The analysis demonstrates that the all trans “tuning-fork” conformation seen in X-ray crystal structure analyses on homologous compounds is also found in microcrystals, in contrast to a proposal by Fringeli et al. (Z. Naturforsch. 27 b, 780 [1972]) that an all cis conformation of the triglyceride exists in solvent-grown microcrystals and in multilayers. The presence of mixed polymorphs is also shown for bulk samples previously examined by X-ray powder diffraction techniques by other workers.
Comparison of Lipid Biosynthesis of Normal and Dark Kept Spinach Leaves in Photosynthetically Active Light
Authors: Heise K.-P. , Krapf G. 
Published: August 2018

Abstract
Upon illumination, dark starved spinach leaves show a 50% reduction of 14C-incorporation capacity into lipids. If 32P-incorporation is measured, the reduction is 85% compared to controls. The relative labelling of the fatty acid residues in total lipids of normal leaves was 80 - 90% compared to 30 - 50% in the darkened material. The kinetics of 14C-incorporation into lipids show that in the controls the majority of 14C was located in the monogalactosyl diglyceride fraction while in the dark kept material phosphatidyl glycerol and phosphatidyl choline were more highly labelled. Corresponding with the changed incorporation capacity a decrease in fatty acid concen­ tration in the glycolipid fraction and a simultaneous increase in the phosphatide fraction in dark pretreated leaves is observed. An illumination period of 30 - 60 minutes at 2×104 lx brings these inverse values back to normal. The most rapid labelling occurred in a glycolipid fraction lacking galactose and having a slightly more hydrophilic character than monogalactosyl diglyceride. The molar ratio of sugar, glycerol and fatty acids in this fraction is 1 : 1 : 1 - 2. The label in the fatty acid residues of this lipid fraction was approximately 10% in dark kept but 90% in control leaves. From 14C-incorporation behavior it is suggested that this lipid is a precursor of monogalactosyl diglyceride. The changes of the labelling pattern of lipids in leaves kept in prolonged darkness are similar to those obtained with 3-(3,4-dichlorophenyl) -1,1-dimethylurea treated Chlorella. A close connection of these effects to the decrease of photosynthetic capacity is therefore suspected. Also the observation that the concentration of α-linolenic acid, bound in the glycolipids, is reduced in dark kept material and increases upon subsequent light exposure, fits into this context. A pos­ sible explanation of these labelling shifts seems to be a pH shift in the various cell-compartments induced by light/dark treatment.
Protolytic Reactions in Photosystem II: a New Model for the Release of Protons Accompanying the Photooxidation of Water
Authors: Saphon Satham , Crofts Antony R. 
Published: August 2018

Using pH indicator dye techniques we have investigated the pH changes in dark-adapted chloro- plasts following excitation by short flashes. Two types of pH indicator, cresol red and neutral red, were used, to follow the pH changes either inside or outside the thylakoids, or the net change when the membrane was made permeable to protons by uncoupling agents.
(1)With cresol red which showed the net pH changes inside and outside the thylakoids, an oscillation of the flash yield of H+ occurred with a periodicity of 4 (minima on the first and fifth flashes, the yield on the third being not significantly different from the yields on the second and fourth flashes). The pH changes did not occur in synchrony with O2-evolution.
(2)The net flash yields without addition of electron acceptor were similar to those with benzyl- viologen. The results were comparable with those obtained with the glass electrode technique by Fowler and Kok (C. F. Fowler and B. Kok, Biochim. Biophys. Acta 357, 299 - 307 [1974]).
(3)The net flash yields with ferricyanide as electron acceptor of photosystem I were higher than those in the absence of acceptor, or with benzylviologen. On the first and fifth flashes a net acidification was always observed.
(4)In the presence of 3- (3,4-dichlorphenyl) -1,1-dimethylurea (DCMU) a rapid acidification also occured on the first flash, while the pH changes induced by subsequent flashes were inhibited.
(5)The uncoupler methylamine did not inhibit the proton uptake outside the thylakoids.
(6)With neutral red as indicator for the net pH change inside and outside the thylakoids, the same oscillation of the flash yield occured as with cresol red.
(7)With neutral red in the precense of an external buffer, as a pH indicator for the internal aqueous phase alone, an oscillation of the flash yield with a periodicity of 4 also occured. The first and second flash yields were higher compared with the third than the equivalent yields of oxygen.
(8)We discuss the results with respect to a model for the release of protons in the water- splitting enzyme reactions, in which protons are not released in synchrony with O2 , but in the transitions of all the states of the watersplitting enzyme with the exception of S1 → S2 .
Our results are consistent with this model when account is taken of the release of protons inside the thylakoids with a periodicity of 2, associated with electron transfer from reduced plastoquinone.
Preparation of Human Erythrocyte Ghosts in Isotonic Solution: Haemoglobin Content and Polypeptide Composition
Authors: Saleemuddin M. , Zimmermann U. , Schneeweiß F. 
Published: August 2018

Abstract
Human red blood cell ghosts were prepared by dielectric breakdown of the cell membrane and subsequent electrical haemolysis in isotonic and isoionic solutions. Almost complete removal of haemoglobin (to about 0.1%) could be achieved by subjecting the erythrocytes suspended in isotonic solution to three consecutive electric field pulses of 16 kV/cm in the presence of 10 mᴍ EDTA, followed by dilution with EDTA-free isoionic medium. The cup-shaped ghost cells were electrically homogeneous. The polypeptide composition of the electrically prepared ghost cells, as analyzed by polyacrylamide electrophoresis in 1% SDS, revealed a pattern similar to ghost cells prepared by osmotic haemolysis. However, the band 6, corresponding to glyceraldehyde-3-phosphate-dehydrogenase protomer, was absent from the electrically prepared ghost cells. Also the band 8, which is eluted at low ionic strength, appeared to be very prominent in the electrical preparations.
Gibberellinaktivität verschiedener Schizaeaceen Antheridiogene im Zwergerbsentest / Gibberellin Activity of Different Antheridiogens in the Dwarf Pea Bioassay
Authors: Bürcky Klaus 
Published: August 2018

Abstract
The antheridiogens (native, antheridia inducing h or­ mones) of both, Anemia phyllitidis (AAn
1 and AAn
2) and Lygodium japonicum (ALy), representatives of the Schizae aceae showed similar effects to GA3 in the dwarf pea bio­ assay.
Struktur und mechanische Eigenschaften dermatosparaktischen Kollagens / Structure and Mechanical Properties of Dermatosparactic Collagen
Authors: Jonak R. , Lapière Ch. M. , Meinel A. , Nemetschek-Gansler H. , Nemetschek Th. , Riedl H. 
Published: August 2018

Abstract
Dermatosparactic calf-tail-tendon-collagen was investigated by mechanical measurements, electron microscopy and x-ray diffraction. We suppose, that the tensile strength decrease of the fibres is due to the irregular aggregation of subfibrils to fibrils. The x-ray diagram of the fibre is not influenced by state of disorder. Cyclic extension of dermatosparactic collagen leads to a higher increase in tensile strength than in the case of normal calf tendon. The effect might be due to the increase of fibril-and area-density resulting in an augmentation of crosslinks.
Interaction of Cibacron Dyes with Dehydrogenases and Kinases
Authors: Bornmann Lothar , Hess Benno 
Published: August 2018

Abstract
Cibacronblue The inhibition of the activity of various kinases and dehydrogenases by Cibacronblue 3 G-A and its structural analogues relies on the interaction of the anthrachinone moiety as well as of the neighbouring phenyl group of the dye with the proteins. Binding is intensified by hydrophobic substituents at the latter ring system.
The Reaction of Aminoacylase with Chloromethylketone Analogs of Amino Acids
Authors: Frey Jürgen , Kordel Werner , Schneider Friedhelm 
Published: August 2018

Abstract
1. Aminoacylase is irreversibly inactivated by the chloromethylketone analogs of benzyloxy-carbonyl-L-alanine, L-alanine, L-leucine, L-aspartic acid (β), tosyl-L-phenylalanine and L-leucyl-L-alanine. The kinetics of the inactivation of the enzyme by the halo-methylketones were investigated.
2. Leucyl-and alanyl chloromethylketone inactivate the enzyme by blocking of 4 SH groups. Experiments with [U-14C] leucyl chloromethylketone confirm that maximal 4 residues are covalently bound to the protein.
3. Inactivation of the enzyme by benzyloxycarbonylalanyl and tosylphenylalanyl chloromethyl­ ketone is the result of the substitution of the £-amino group of one lysine residue per active site and not of SH groups. However, in the presence of competitive inhibitors these halomethylketones react only with the SH groups of the enzyme, too.