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11.
Christoph Theurer Hans-Joachim Treumann Thomas Faust Ursula May Wolfgang Kreis 《Plant Cell, Tissue and Organ Culture》1994,38(2-3):327-335
The glycosylation and deglycosylation of cardiac glycosides was investigated using cell suspension cultures and shoot cultures, both established from Digitalis lanata EHRH. plants, as well as isolated enzymes. Shoots were capable of glucosylating digitoxigenin, evatromonoside, digiproside, glucodigitoxigenin and digitoxin. Suspension cultured Digitalis cells glucosylated all the substrates mentioned but digiproside, whereas the UDP-glucosedependent cardinolide glucosyltransferase isolated from that source did not accept digitoxigenin and digiproside as substrates. It is concluded that at least three different glucosyltransferases are involved in cardiac glycoside formation in Digitalis. Similar experiments carried out with glucosylated cardenolides which were administered to cultured cells, shoots and a cardenolide -glucosidase isolated from young leaves revealed that at least two different glucosidases occur in Digitalis lanata, albeit in different tissues or during different phases of development. The biotransformation of glucoevatromonoside was investigated using unlabelled compound and [14C-glucose]-glucoevatromonoside synthesized enzymatically. After 7 d of incubation almost no radioactivity could be recovered from the cardenolide fraction, indicating that the terminal glucose of glucoevatromonoside was now incorporated into volatile, hydrophilic and insoluble compounds. Since, on the other hand, large amounts of cardenolides were found in the experiments with unlabelled glucoevatromonoside it is assumed that steady state or pool size regulation is achieved by the coordinated action of a cardenolide glucosidase and a glucosyltransferase.Abbreviations Acdox
D-acetyldigitoxose
- dgen
digoxigenin
- dox
D-digitoxose
- dten
digitoxigenin
- dtl
D-digitalose
- fuc
D-fucose
- gten
gitoxigenin
- qun
D-quinovose
- CGH
cardenolide 16-O-glucohydrolase
- DFT
UDP-fucose:digitoxigenin 3-O-fucosyltransferase
- DGT
UDP-glucose:Digitoxin 16-O-glucosyltransferase
- DQT
UDP-quinovose:digitoxigenin 3-O-quinovosyltransferase 相似文献
12.
Dietmar Helmut Pieper Karin Stadler-Fritzsche Karl-Heinrich Engesser Hans-Joachim Knackmuss 《Archives of microbiology》1993,160(3):169-178
2-Chloro-4-methylphenoxyacetate is not a growth substrate for Alcaligenes eutrophus JMP 134 and JMP 1341. It is, however, being transformed by enzymes of 2,4-dichlorophenoxyacetic acid metabolism to 2-chloro-4-methyl-cis, cis-muconate, which is converted by enzymatic 1,4-cycloisomerization to 4-carboxymethyl-2-chloro-4-methylmuconolactone as a dead end metabolite. Chemically, only 3,6-cycloisomerization occurs, giving rise to both diastereomers of 4-carboxychloromethyl-3-methylbut-2-en-4-olide. Those lactones harbonring a chlorosubstituent on the 4-carboxymethyl side chain were surprisingly stable under physiological as well as acidic conditions. 相似文献
13.
Bilateral damage of the medial temporal lobe system prevents the formation of new declarative memories but leaves intact knowledge that was acquired before damage. For motor learning, no structure has been identified that plays a comparable role for the consolidation of motor memories. The deficits of motor learning are focal and show a similar allocation to the various of motor learning are focal and show a similar allocation to the various sensorimotor subsystems, as do the corresponding non-mnemonic functions. The involvement of sensorimotor circuitries changes during motor learning so that association areas are preferentially activated in the early stages, and cerebello- and striato-motor-cortical loops are preferentially activated in the late stages of motor learning. Recent neuroanatomical and neurophysiological findings on the effects of brain lesions in human and non-human primates are discussed. 相似文献
14.
Gesche Heiss Natalie Trachtmann Yoshikatsu Abe Masahiro Takeo Hans-Joachim Knackmuss 《Applied microbiology》2003,69(5):2748-2754
Rhodococcus (opacus) erythropolis HL PM-1 grows on 2,4,6-trinitrophenol or 2,4-dinitrophenol (2,4-DNP) as a sole nitrogen source. The NADPH-dependent F420 reductase (NDFR; encoded by npdG) and the hydride transferase II (HTII; encoded by npdI) of the strain were previously shown to convert both nitrophenols to their respective hydride Meisenheimer complexes. In the present study, npdG and npdI were amplified from six 2,4-DNP degrading Rhodococcus spp. The genes showed sequence similarities of 86 to 99% to the respective npd genes of strain HL PM-1. Heterologous expression of the npdG and npdI genes showed that they were involved in 2,4-DNP degradation. Sequence analyses of both the NDFRs and the HTIIs revealed conserved domains which may be involved in binding of NADPH or F420. Phylogenetic analyses of the NDFRs showed that they represent a new group in the family of F420-dependent NADPH reductases. Phylogenetic analyses of the HTIIs revealed that they form an additional group in the family of F420-dependent glucose-6-phosphate dehydrogenases and F420-dependent N5,N10-methylenetetrahydromethanopterin reductases. Thus, the NDFRs and the HTIIs may each represent a novel group of F420-dependent enzymes involved in catabolism. 相似文献
15.
16.
Klaus Kayser Sabine André Gerhard Böhm Sonia Donaldo-Jacinto Peter Fritz Herbert Kaltner Gian Kayser Wolf-Peter Kunze Andreas Nehrlich Fu-Yue Zeng Hans-Joachim Gabius 《Development genes and evolution》1995,204(5):344-349
Protein-carbohydrate interactions are supposed to play key roles in the mechanisms of cell adhesion, biosignalling and intracellular routing, warranting the analysis of the developmental course of expression of epitopes of this system. Thus, a panel of carrier-immobilized carbohydrate ligands was used as probes, namely lactose,N-acetylgalactosamine,N-acetylglucosamine, mannose, fucose and maltose. Additionally, an antibody to an endogenous -galactoside-binding lectin (anti-galectin-1), the biotinylated lectin and two further human lectins, namely the macrophage migration inhibitory factor-binding sarcolectin and serum amyloid P component (SAP) that displays selectivity for sulphated sugars and mannose-6-phosphate, were included. They enabled us to assess the extent of the presence of respective binding sites in fixed sections from human lungs (pulmonary epithelial cells), livers (hepatocytes) and hearts (myocard cells) of 10–50 weeks gestation. Invariably, specific binding was detected in the three organ types, at least in certain stages. In most of the cases, the intensity of staining exhibited developmental regulation. The apparent patterns reveal similarities between the different cell types, as seen with immobilizedN-acetylglucosamine as well as with labelled galectin-1 and sarcolectin. However, drastic differences among such patterns with nearly opposite developmental courses do also occur, as detected for carrier-attached mannose and maltose residues. These results point to a potential importance for the detected glycohistochemical features in human development and substantiate the possibility of differential regulation of the presence of binding sites for distinct sugars within a certain organ and between the individual cell types of the monitored organs. 相似文献
17.
Schönheit Peter Beimborn Dieter B. Perski Hans-Joachim 《Archives of microbiology》1984,140(2-3):247-251
Cultures of Methanobacterium thermoautotrophicum (Marburg) growing on media low in potassium accumulated the cation up to a maximal concentration gradient ([K+]intracellular/[K+]extracellular) of approximately 50,000-fold. Under these conditions, the membrane potential was determined by measuring the equilibrium distribution of the lipophilic cation (14C) tetraphenylphosphonium (TPP+). This cation was accumulated by the cells 350-to 1,000-fold corresponding to a membrane potential (inside negative) of 170–200 mV. The pH gradient, as measured by equilibrium distribution of the weak acid, benzoic acid, was found to be lower than 0.1 pH units (extracellular pH=6.8). The addition of valinomycin (0.5–1 nmol/mg cells) to the culture reduced the maximal concentration gradient of potassium from 50,000-to approximately 500-fold, without changing the membrane potential. After dissipation of the membrane potential by the addition of 12C-TTP+ (2 mol/mg cells) or tetrachlorosalicylanilide (3 nmol/mg cells), a rapid and complete efflux of potassium was observed.These data indicate that potassium accumulation in the absence of valinomycin is not in equilibrium with the membrane potential. It is concluded that at low extracellular K+ concentrations potassium is not accumulated by M. thermoautotrophicum via an electrogenic uniport mechanism.Non-common abbreviations TPP+
Tetra phenylphosphonium bromide
- DTE
Dithioerythritol
- TCS
3,5,3,4-Tetrachlorosalycylanilide 相似文献
18.
Werner Nachtigall und Hans-Joachim Rothe 《Journal of Ornithology》1982,123(4):439-443
Zusammenfassung Bei Haustauben, die in einem horizontalen Windkanal mit 48 km/h stationär flogen, wurden mit Hilfe von Zeitlupenanalysen Schlagphasen nachgewiesen, die dem vonWeis-Fogh (1973) geforderten clap-and-fling Mechanismus entsprechen. Am Ende des Aufschlags schlagen die beiden Flügel mit der morphologischen Oberseite ± vollständig zusammen (clap). Vor dem Abschlag öffnen sie sich wie die Seiten eines Buches von vorn nach hinten (fling); erst am Ende dieser Phase entfernen sie sich voneinander. Weitere feinkinematische Ergebnisse werden mitgeteilt. Diese instationären Schlagphasen werden insbesondere dann eingesetzt, wenn hohe Luftkräfte benötigt werden. Die Kinematik der Flügelbewegung ist demnach so beschaffen, daß durch frühzeitige Zirkulationsinduzierung bereits ganz zu Beginn des Abschlags hohe Auftriebskräfte erzeugt werden könnten. Es wird diskutiert, daß der clap-and-fling Mechanismus auch für rasche Beschleunigungen bei hohem Schubbedarf eingesetzt werden könnte.
Mit Geräteunterstützung durch die Deutsche Forschungsgemeinschaft 相似文献
Evidence for a clap-and-fling mechanism in pigeons flying in a windtunnel
Summary Slow motion pictures of pigeons flying horizontally at a speed of 48 km/h in a windtunnel have shown flight patterns which seemed to be similar to the clap-and-fling mechanism discribed byWeis-Fogh (1973) for small insects. At the end of upstroke, both upper surfaces of the wings come together ± completely (clap). Before downstroke, the wings are opened like the pages of a book (fling). This instationary wingbeat pattern is used especially when high aerodynamic forces are needed. The clap-and-fling mechanism enables the bird to establish an early circulation so that, at the very beginning of downstroke, high lift forces can be produced. The question whether the clap-and-fling mechanism is also used for quick accelerations when greater thrust is required is also discussed.
Mit Geräteunterstützung durch die Deutsche Forschungsgemeinschaft 相似文献
19.
The effect of 100 atm pressure on the organization of the lipid-peptide complex formed between polymyxin and dipalmitoyl phosphatidic acid has been investigated. Phase transition curves were obtained by electron paramagnetic resonance by measuring the partition coefficient of the spin label, 2, 2, 5, . The three-step phase transition curve previously obtained with fluorescence polarization measurements was confirmed, demonstrating three distinct phosphatidic acid domains in the bilayer. Pressure increases binding of polymyxin to phosphatidic acid bilayers and alters the proportions of the two domains that differ in the mode of binding between phosphatidic acid and polymyxin. The binding curves of polymyxin to phosphatidic acid bilayers were determined and it was shown that application of pressure reduces the cooperativity of the binding curve. 相似文献
20.
Hans-Ulrich Meisch Helga Benzschawel Hans-Joachim Bielig 《Archives of microbiology》1977,114(1):67-70
Cells of Chlorella pyrenoidosa, derived from vanadium free agar slants, respond with great sensitivity to microamounts of vanadium, added as NH4VO3 to autotrophic liquid cultures. Between 0.01 and 1 g V per litre nutrient medium (2·10-10-2·10-8g-at/l), the algae respond with a continuous increase in dry weight. At higher V-concentrations, further enhancement in biomass is accompanied by a additional increase in chlorophyll content. Maximum V-effect on both parameters was found to be at 500g V/l (10-5 g-at/l). Dry weight as well as chlorophyll content of Chlorella are decreased by concentrations above 25 mg V/l; 100 mg V/l (2·10-3 g-at/l) stop growth and cause death of the cells. The toxic threshold for the V-content in the algae was determined to be at 150–200 g V/g (3–4·10-6 g-at/g) dry weight.Two different pH-optima for a positive vanadium action on dry weight and chlorophyll biosynthesis were established, the first at pH 7, the other in the range pH 7.5–8. Two sites of vanadium action in green algae are discussed.Part I: Arch. Microbiol. 105, 77–82 (1975) 相似文献