bluuebunny/crossref_metadata_2025_split huggingface dataset:
Über Primärreaktionen beim Sehvorgang. Thermodynamischer und kinetischer Einfluß des pH-Wertes auf die Metarhodopsin-I-II-Umwandlung Protonenverbrauch als Auswirkung einer Konform ationsänderung / Primary Reactions in the Visual Process Thermodynamic and Kinetic Influence of pH on the Metarhodopsin I-II Transition Proton Consumption as an Effect of a Conformation Change
Authors: Emrich Hinderk M. , Reich Roland 
Published: August 2018

Abstract
In isolated bovine rod outer segments metarhodopsin I -II absorption-changes are measured using rapid flash-photometry. The rapid H+-uptake accompanying this transition is measured using phthaleine pH-indicators.
1. The meta I -II equilibrium is pH-dependent in the same manner as the proton uptake (Figs 1 ,1 4). This can be explained by the assumption that the meta II conformation is stabilized by the protonization of an amino-group, which in its protonized state cannot be re-enfolded into the hydrophobic core of the molecule, since it is too polar (Fig. 15). In the proposed model the con­ formation-regulating proton binding group is not in the chromophoric region of rhodopsin. This resolves the well known contradiction between the expected bathochromic and observed hypso-chromic shift of meta II H+.
The model furthermore involves that the dissociation-constant of the protonized group differs from the measured apparent pK = 6.3.
2. The meta I -II transition is H+ (and OH-)-catalysed (Figs 4, 5). The kinetics show usually a characteristic deviation from a first-order process (Fig. 2). This can be explained by some in­ homogeneity of the rhodopsin-molecules e. g. some differences in the shieldings of the catalytic centers from H+ (and OH-).
3. The activation energy decreases with increasing proton-concentration (Fig. 6). The protons seem to open a new reaction pathway with a smaller activation energy.
4. Triton X 100 and ethanol increase, sodium-desoxycholate slows down the velocity of the M-I-II-transition, whereas digitonin has only a small effect (Fig. 7).
5. The relaxation-velocity of the optical pH-signal depends on the structural state of the rhodopsin-containing substrate (Figs 10. 11). The outer membrane of the outer segment and the disc-membrane are regarded as possible H+-diffusion-barriers (Fig. 12), because the time lag between MII-signal and pH-signal is nearly eliminated, when the membranes are destroyed by digitonin.
6. In some experiments, using successive non-saturating flashes, an initial H+-uptake of 2 - 3 H+/MII was observed (Fig. 17). After full-bleaching, however, the ΣH+/ΣMII-ratio is one. The hypothesis of a conformative coupling of 2 - 3 rhodopsin-molecules is presented (Fig. 18). The possible existence of an "unfolded" state of rhodopsin is discussed on the basis of a photo-regeneration-experiment, in which no H+-release was observed (Figs 19, 20)
Interferon Effect on Cellular Functions: Enhancement of Virus Induced Inhibition of Host Cell Protein Synthesis in Interferon-Treated Cells
Authors: Suh M , Bodo G , Wolf W , Viehhauser G , Jungwirth C 
Published: August 2018

Abstract
Total protein synthesis in mouse cells but not in confluent chick embryo fibroblasts (CEF) is inhibited shortly after infection with vaccinia virus. This inhibition by the infecting virus is enhanced drastically if the mouse cells have been pretreated with homologous interferon pre­parations. The enhanced reduction of protein synthesis also occurs if the cells are treated with actinomycin D and is therefore to a large extent caused by an enhanced inhibition of amino acid incorporation into host cell proteins. Enhanced inhibition of total protein synthesis during the early stages of infection may be a prerequisite for the complete degeneration of the cells (lysis) which occurs later. Various alterations of mouse cells and chick embryo fibroblasts due to exposure to homologous interferon preparations are discussed with respect to the antiviral state induced in these cells
Direct Demonstration of Dielectric Breakdown in the Membranes of Valonia utricularis
Authors: Coster Hans G. L. , Zimmermann Ulrich 
Published: August 2018

Abstract
It is shown that if the membrane potential of cells of Valonia utricularis was increased rapidly by applying ~500 μs current pulses, dielectric breakdown of the membrane occured when the potential reached a value of ~0.85 V.
The breakdown phenomenon observed was not associated with global damage to the cell or its membrane. The process could be repeated after a short resealing time (~ 10s), many times on a single cell.
The rapidity of the breakdown process (~1 μs) rules out the possibility that dielectric breakdown occurs by a mechanism similar to that of punch-through, which involves changes in ionic profiles.
Interaction between Dehydrogenases and a New NAD⊕-Isomer
Authors: Jeck Reinhard , Woenckhaus Christoph , Holý Antonin 
Published: August 2018

Abstract
A new NAD⊕-isomer was prepared, in which the ᴅ-ribose of the adenosine moiety was sub­ stituted by the enantiomeric ʟ-ribose. As compared to nicotinamide-adenine-dinucleotide (NAD⊕) and NADH the coenzyme isomer (ᴅ,ʟ)-NAD⊕ and its dihydroform (ᴅ,ʟ)-NADH are far less tightly bound to lactate dehydrogenase and alcohol dehydrogenase from horse liver. In the presence of the second substrate (ᴅ,ʟ)-NAD⊕ and (ᴅ,ʟ)-NADH act as hydrogen acceptor and hydrogen donator, respectively, with lactate dehydrogenase and alcohol dehydrogenases from horse liver and yeast. Compared to NAD⊕ and NADH the Michaelis constants are always increased, the catalytic constants (V/Et) were found to be decreased except for the dihydroform reacting with alcohol dehydrogenase from liver.
Synthese einer Partialsequenz aus dem aktiven Zentrum der Streptokokken-Proteinase (EC.3.4.22.10), VI / Synthesis of a Fragment of the Active Center of the Streptococcal Proteinase (EC 3.4.22.10), VI
Authors: Raschig Andreas , Schneider Friedhelm 
Published: August 2018

Abstract
Streptococcal Proteinase, Active Center Peptide, Peptide Synthesis The synthesis and properties of the protected peptide Boc-His(Boc)-Cys(X)-Val-OH(ONP) [X = ferf-butylmercapto, p-methoxybenzyl, tetrahydropyranyl-(2) ] are described. This peptide is a fragment of an active center sequence of the streptococcal proteinase (EC 3.4.22.-10) containing the essential SH group of the enzyme.
Lysolecithin Induced Membrane Alterations in Thymocytes
Authors: Weltzien Hans Ulrich 
Published: August 2018

Abstract
The effects of lysolecithin and of 2 synthetic ether-desoxy lysolecithin analogs, containing alkyl residues of 16 or 12 carbon atoms, on the agglutination kinetics of calf and rabbit thymocytes by concanavalin A (Con A) were investigated. Unlike the natural lysolecithin, these synthetic analogs are resistant to metabolism by membrane associated enzymes. It was found that pretreatment of thymocytes with lysolecithin or with the C16-analog leads to slightly increased agglutination rates. The C12-analog, in contrast, significantly inhibits thymocyte agglutination by Con A. More­ over, a comparison of these results with lysophosphatide effects on the agglutinability of erythrocytes of various species revealed that the inhibitory effect of the short-chain phosphatide is rather specific for thymocytes. The finding that long-and short-chain lysophosphatides, which have previously been shown to react as adjuvants or immunosuppressants, respectively, induce adserve alterations in thymocyte membranes indicates that these substances may affect the immune response by changing the membrane properties of immune competent cells. Concerning the nature of these membrane alterations it was shown that lysolecithin did not affect the number of Con A receptors per cell nor the affinity of lectin binding. It is therefore concluded that the lysophosphatide in­ duced alterations of Con A agglutinability can not be caused by an uncovering or covering of lectin-receptors.
Der elektronenmikroskopische Nachweis der fibrillären Natur des Silberliniensystems bei peritrichen Ciliaten / Electronmicroscopical Demonstration of the Fibrillar Nature of the Silverline System in Peritrich Ciliates
Authors: Foissner Wilhelm 
Published: August 2018

Abstract
A comparative light and electronmicroscopical study about the structure of the cortex, and the location and nature of the silverlines of Telotrochidium elongatum was performed. There is a fibril in the epiplasm below each pellicular ridge. Ultrathin sections of silver stained specimens demonstrate that silver is deposited at and in these fibrills, not only in animals stained with the wet silver method but also in animals stained with the dry one. These findings confirm Klein’s and our own view about the fibrillar nature of the silverline system. The significance of our findings for the elucidation of the structure and function of the cortex is discussed.
Transport and Processing of Ribosomal RNA in Plant Cells after Treatment with Cycloheximide
Authors: Gebauer Hans-Ullrich , Seitz Ursula , Seitz Ulrich 
Published: August 2018

Abstract
In freely suspended cells of parsley (Petroselinum crispum ) protein synthesis is inhibited nearly totally by 5 /ug/ml cycloheximide within 10 min. This very low dose has a slight effect on the rRNA synthesis too. During an incubation period of 60 min with [32P] orthophosphate in the presence of the inhibitor (5 /ugjml) at least 65 - 70% mature rRNA are synthesized compared with the control. After 120 min the synthesis is progressively reduced to 60 - 65%, and after 240 min to 30-40% .
Cycloheximide causes a delay of the processing of the precursor RNA species leading to an accumulation of these components. In addition to the 2.3 x 10® daltons RNA, normally detectable in pulse experiments, two further precursor molecules do emerge which under normal circumstances apparently are shortlived. Their molecular weights are 2.0 x 10® and 0.9 x 10® daltons.
The pulse-chase technique and cell fractionation into nuclear and ribosomal parts enables us to demonstrate a rapid transfer of labelled 18S and 25S RNA during a 15 min chase treatment to the mature cytoplasmic ribosomes. Under these conditions no differential transport of the two components takes place.
The cells possess a pool of proteins. Therefore the formation of RNP-particles or ribosomes respectively and the transport from the nucleus to the cytoplasm are independent from protein synthesis for some time
Über die Bedeutung paranodaler Strukturen für die Impulsregeneration am Ranvier’schen Schnürring / About the Importance of Paranodal Structures of the Ranvier Node for the Impulse Regeneration
Authors: Müller-Mohnssen Helmuth , Tippe Armin , Hillenkamp Franz , Unsold Eberhard 
Published: August 2018

Abstract
The site of the pulse regeneration in myelinated nerve is generally assumed to be the unmyelinated part of the axon membrane in the Ranvier node. To check this, a micro-irradiation technique using laser pulses (λ = 347 nm, t = 2 0 ns) was used to produce morphological lesions of about 1 /(m diameter in various regions of the Ranvier node. The electro-physiological functions were monitored parallel to the irradiation. Depending on the localization of the lesions two types of changes in these functions were observed:
1. If a definite site in the paranodal myelin sheath was damaged without affecting the axon, an action potential could no longer be elicited, although the resting potential as well as the stationary current-voltage behaviour remained unchanged.
2. A damage of the axon resulted in a break down of membrane potential and resistance. In most of the cases the excitability recovered after spontaneous or current induced restitution of the membrane resting potential and resistance.
These observations indicate, that structures in the paranodal region are vital for the Na+-activation and inactivation. The membrane potential and stationary current-voltage behaviour can be attributed to the axon membrane. A new hypothesis concerning the mechanism of the Na+-activationinactivation process is suggested
Carotinoide in Zygaena -Arten (Lepidoptera)/ Carotenoids in Zygaena Species (Lepidoptera)
Authors: Bornefeld T , Czygan Franz-C 
Published: August 2018

Abstract
Species of Zygaena (Lepidoptera) have been fed with leaves of Lathyrus pratensis rich in chlorophylls and carotenoids. The metabolism of the pigments was followed in eggs, larvae, pupae, and imagines of the insects. No chlorophylls, only lutein - the main carotenoid of the food plants - was stored in the animals. Traces of α-zeacarotene, absent in plants, could be found in eggs and larvae
The Inhibition of Carotenoid Biosynthesis in Green Algae by SANDOZ H 6706: Accumulation of Phytoene and Phytofluene in Chlorella fusca
Authors: Kümmel H. W. , Grimme L. H. 
Published: August 2018

Abstract
Prolonged cultivation of the green alga Chlorella fusca under heterotrophic conditions and in the presence of sub-lethal concentrations of SAN H 6706 (4-chloro-5-(dimethylamino)-2-(α,α,α-tri-fluoro-m-tolyl)-3 (2H)-pyridazinone) leads to an accumulation of phytoene and phytofluene. The content of chlorophylls and coloured carotenoids of the cells treated with this herbicide, compared with normal untreated cells, is diminished by about 90% and 95% respectively, but the total amount of carotenoids, including colourless phytoene and phytofluene, is increased by 65%. This suggests that SAN H 6706 causes increased accumulation of carotenoids by eliminating a biosynthetic control mechanism, so that the endproducts of the biosynthetic chain no longer control the rate of precursor formation.
On the Structure of Lignin from Soybean Cell Suspension Cultures
Authors: Nimz H. , Ebel J. , Grisebach H. 
Published: August 2018

Abstract
Treatment of soybean cell cultures according to the Björkman-procedure yields a “milled wood lignin” (MWL), which has been shown to be a hardwood lignin by thermofractography and carbon-13-NMR spectroscopy. The 13C-NMR spectrum of this acetylated lignin indicates that this lignin contains relatively high amounts of cinnamyl alcohol and p-hydroxyphenyl groups compared with other typical hardwood lignins. The 13C-spectrum of the acetylated MWL also indicates the presence of carbohydrate components, which are apparently very tightly bound to the lignin.
Reaction of Glutathione with Conjugated Carbonyls
Authors: Esterbauer Hermann , Zöllner Helmward , Scholz Norbert 
Published: August 2018

Abstract
1. GSH reacts with conjugated carbonyls according to the equation: G SH+R-CH=CH-COR⇆R-CH(SG)-CH2-COR. The forward reaction follows second order, the reverse reaction first order kinetics. It is assumed that this reaction reflects best the ability of conjugated carbonyls to inactivate SH groups in biological systems.
2. The rate of forward reaction increases with pH approx. parallel with αSH. Besides OH- ions also proton donors (e. g. buffers) increase the rate. The catalytic effect of pH and buffer is inter­ preted in view of the reaction mechanism.
3. The equilibrium constants as well as the rate constants for forward (k1) and reverse reaction show an extreme variation depending on the carbonyl structure. Acrolein and methyl vinyl ketone (kt = 120 and 32 mol-1 sec-1 , resp.) react more rapidly than any other carbonyl to give very stable adducts (half-lives for reverse reaction 4.6 and 60.7 days, resp.). Somewhat less reactive are 4-hydroxy-2-alkenals and 4-ketopentenoic acid (k1 between 1 and 3 mol-1 sec-1), but they also form very stable adducts showing half-lives between 3.4 and 19 days. All other carbonyl studied react either very slowly (e. g. citral, ethly crotonate, mesityl oxide, acrylic acid) or form very labile adducts (crotonal, pentenal, hexenal, 3-methyl-butenone). Comparing biological activities of con­ jugated carbonyls their reactivity towards HS (k1) and the stability of the adducts must be considered.
Photoreactions of Cytochrome b6 and Cytochrome f in Chloroplast Photosystem I Fragments
Authors: Böhme H 
Published: August 2018

Abstract
Photosystem I fragments were prepared by digitonin treatment of spinach chloroplasts. The mid­point potential of cytochrome b6 in the fragments is close to 0 V, showing a one electron transition. No cytochrome b559 was detectable, neither in difference absorption spectra nor in light-induced absorbance changes. In the absence of added cofactors only cytochrome b6 photoreduction can be observed. This photoreduction is stimulated by ferredoxin. Ferredoxin-NADP+ reductase appears not to be involved in cytochrome b6 reduction. Photooxidation of cytochrome b6 is dependent on plastocyanin addition and inhibited by DBMIB, a plastoquinone antagonist. Addition of plastocyanin restores cytochrome f photooxidation as well, reacting quite specifically in about equimolar concentrations to bound cytochrome f. The stimulation of cytochrome f oxidation is abolished by an antibody prepared against plastocyanin, indicating a surface location of plastocyanin in digitonin treated membranes.
Biphasic kinetics of dark-reduction of cytochrome f by ascorbate indicate that part of this cyto­chrome f is relatively inaccessible in the membrane. After preillumination a monophasic reduction is observed and the slowly oxidized component is absent. Illumination in the presence of plastocyanin causes a fast and complete reduction of cytochrome f, suggesting equilibration of cyto­chrome f with added plastocyanin, residing in the membrane surface. It appears that actinic light causes conformation and/or structural changes in the membrane of these digitonin fragments, influencing cytochrome f accessibility.
The Chlorophyll aII Reaction in Trypsin-Treated Spinach Chloroplasts in the Presence of Potassium Ferricyanide
Authors: Döring Günter 
Published: August 2018

Abstract
In trypsin-treated spinach chloroplasts there is no linear electron flow from water to potassium ferricyanide. The chlorophyll aII reaction, however, is still active but insensitive to 3-(3,4-dichloro-phenyl)-1,1-dimethylurea. From this we conclude that ferricyanide and trypsin together stimulate a mini-cycle in photosystem II.
Redundante Nucleotid-Sequenzen in DNA aus Weizen / Redundant Nucleotide-Sequences in DNA from Wheat
Authors: Kern Hartmut , Grübler Joachim 
Published: August 2018

Abstract
DNA from dormant and germinated embryos exhibit differences in the kinetics of reassociation of thermal denatured nucleic acid. Within 24 h of germination a reduction of the renaturation, expressed as Cot1/2 of the redundant fraction, is detectable.
Isolation o f β, β-Caroten-2-ol from an Insect, Cerura vinula (Lepidoptera)
Authors: Kayser Hartmut 
Published: August 2018

Abstract
The monohydroxy carotenoid from the moth Cerura vinula has been shown to be β,β-caroten-2-ol on the basis of electronic, infrared, proton magnetic-resonance, and mass spectra. On acid treatment in the presence of molecular oxygen this carotenoid is dehydrogenated to 4′,5-retro-β, β-caroten-2-one. The identification of β, β-caroten-2-ol by its retro product, its time course of acetylation, and its chromatographic properties relative to β, β-caroten-3-ol and β, β-caroten-4-ol is discussed.
This is the first demonstration of a 2-hydroxylated carotenoid in an insect. Implications on the biogenesis of this pigment are considered.
Kinetic Properties of Mg, Ca ATPase from Various Escherichia coli Mutants
Authors: Ahlers Jan , Günther Theodor , Schrandt Irene 
Published: August 2018

Abstract
The ATPase is not lacking in the ATPase mutants DL 54 and AN120 but has very different kinetic properties including a higher Cl- optimum and higher Km values for MgATP. In AN 120, the ATPase activity also has a higher Mg2+ optimum.
Coupling Factor Adenosine-5′-triphosphatase from Rho do spirillum rubrum: A Simple and Rapid Procedure for Its Purification
Authors: Lücke Friedrich-Karl , Klemme Jobst-Heinrich 
Published: August 2018

When photosynthetic membranes from Rhodospirillum rubrum, devoid of loosely bound small molecules and proteins, were passed through a French-pressure cell, the enzyme adenosine-5′-triphosphatase (EC 3.6.1.3.) (ATPase) was released into the soluble fraction.
The solubilized ATPase was purified to homogeneity. In many respects it behaved like the enzyme purified by other workers, but it also hydrolyzed Mg-ATP with a small, but significant rate. Furthermore, it was much more stable.
Maximal restoration of photophosphorylation in ATPase-depleted membranes was achieved by addition of about 1 mg purified ATPase per mg bacteriochlorophyll. For reconstitution of NAD+- photoreduction, about half of this amount was saturating.
Inhibition of Electron Transport on the Oxygen-Evolving Side of Photosystem II by an Antiserum to a Polypeptide Isolated from the Thylakoid Membrane
Authors: Schmid Georg , Menke Wilhelm , Koenig Friederike , Radunz Alfons 
Published: August 2018

Abstract
A polypeptide fraction with the apparent molecular weight 11000 was isolated from stroma-freed chloroplasts from Anthirrhinum majus. An antiserum to this polypeptide fraction inhibits photosynthetic electron transport in chloroplasts from Nicotiana tabacum. The relative degree of inhibition is pH dependent and has its maximum at pH 7.4. The maximal inhibition observed was 93%. The dependence of the inhibition on the amount of antiserum yields a sigmoidal curve which hints at a cooperative effect. A calculation of the Hill interaction coefficient gave the value of 10. The inhibition occurs on the water splitting side of photosystem II between the sites of electron donation of tetramethyl benzidine and diphenylcarbazide. Tetramethyl benzidine donates its electrons before the site where diphenylcarbazide feeds in its electrons. Analysis of the steady state level of the variable fluorescence also indicates that the inhibition site is on the water splitting side of photosystem II. Tris-washed chloroplasts are equally inhibited by the antiserum and the inhibition is also observed in the presence of an inhibitor of photophosphorylation like dicyclo-hexyl carbodiimide and in the presence of the uncoupler carbonylcyanide m-chlorophenyl hydra-zone (CCCP) which means that the inhibitory action is directed towards the electron transport chain. Valinomycin which is supposed to affect the cation permeability of the thylakoid membrane has no influence on the inhibitory action of the antiserum. The same is valid for gramicidin. Methylamine on the other hand can induce a state in the thylakoids in which the antiserum is not effective. If the antibodies are already adsorbed prior to the methylamine addition then the high inhibitory effect by the antiserum remains unchanged upon addition of methylamine.
From the experiments it follows that a component from the vicinity of photosystem II is ac­cessible to antibodies that is, the component is located in the outer surface of the thylakoid mem­ brane. It appears that the inhibitory effect is produced in the course of the light reaction.
Untersuchungen zur direkten Markierung von Aminosäuren durch hochenergetische 11C -Atome aus Kernreaktionen / Direct Labeling of Amino Acids by Means of Hot 11C-Atoms
Authors: Gundlach G. , Sattler E.L. , Trampisch W. , Wagenbach U. 
Published: August 2018

Abstract
Recoillabeling of amino acids can be accomplished in good radiochemical yield in solid state only. Labeling in solution or in mixture with charcoal or silicagel results in formation of a variety of different products.
Transduction of Turgor Pressure by Cell Membrane Compression
Authors: Coster H.G.L. , Zimmermann U. 
Published: August 2018

Abstract
It is suggested that turgor pressure sensing in plant cells occurs via compression of the cell membranes; either at the plasmalemma where a pressure gradient exists, or the tonoplast due to the pressure developed inside the cell. Considerations of electro-mechanical forces in electrical breakdown of cells suggests that significant changes in the thickness of some regions of the membrane can indeed occur. It is readily envisaged how such changes in membrane thickness can be coupled to changes in active transport processes.