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  • 1
    Electronic Resource
    Electronic Resource
    Photochemistry of nonconjugated bichromophoric systems. Mechanism of the intramolecular photocycloaddition of biscoumarins in solution (1974)
    s.l. : American Chemical Society
    Journal of the American Chemical Society 96 (1974), S. 6994-7000 
    Details
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ja00829a030
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  • 2
    Electronic Resource
    Electronic Resource
    Glucose-fructose oxidoreductase, a periplasmic enzyme of Zymomonas mobilis, is active in its precursor form (1993)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 107 (1993), S. 0 
    Details
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract Glucose-fructose oxidoreductase (GFOR) is a periplasmic enzyme of the ethanologenic, Gram-negative bacterium Zymomonas mobilis. It contains tightly bound NADP+ as cofactor. In Z. mobilis GFOR-recombinant strains, a precursor form of GFOR was accumulated. To assay the preGFOR for its NADP(H) content and enzymatic activity, it was purified from an overproducing strain. Using SDS-PAGE, the precursor subunit size was determined to approximately 45 kDa (compared with a 40 kDa subunit size for the mature GFOR subunit). The N-terminal amino acid sequence of the precursor was determined. The N-terminal residues of the GFOR matched with the signal sequence from the DNA sequence of the gene gfo. The precursor form of GFOR was enzymatically active and contained the cofactor NADP(H).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6968.1993.tb06045.x
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  • 3
    Electronic Resource
    Electronic Resource
    Localisation of the glucose-fructose oxidoreductase in wild type and overproducing strains of Zymomonas mobilis (1991)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 84 (1991), S. 0 
    Details
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract The enzyme glucose-fructose oxidoreductase (GFOR) from the Gram-negative ethanologenic bacterium Zymomonas mobilis was purified to homogeneity and was shown to be a tetrameric protein with a subunit size of Mr 42 500. Using immunogold-labelling in combination with electron microscopy, ultrathin sections of Z. mobilis wild type cells showed that the enzyme GFOR is located in the periplasm off the bacterial cells. Z. mobilis strains which carried the cloned gfo gene on plasmid pSUP104, had 5–6-fold increased GFOR enzyme activities. Moreover, these cells accumulated large amounts of a presumable unprocessed pre-GFOR protein (Mr 48 000).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6968.1991.tb04598.x
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  • 4
    Electronic Resource
    Electronic Resource
    The Mode of Activation of a Barrel Column: Response Properties of Single Units in the Somatosensory Cortex of the Mouse upon Whisker Deflection (1993)
    Oxford, UK : Blackwell Publishing Ltd
    European journal of neuroscience 5 (1993), S. 0 
    Details
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Response properties of single units in the mouse barrel cortex were studied to determine the sequence in which the neurons that form a cortical column become activated by a single‘natural’stimulus. Mice (n= 11) were anaesthetized with urethane. For a total of 153 cells, grouped by cortical layer, responses to a standardized deflection of a single whisker were characterized using poststimulus time and latency histograms. Usually, for each unit, data were collected for stimulation of its principal whisker (PW; the whiskers corresponding to the barrel column in which the cell was located) and of the four whiskers surrounding the PW. In all layers, PW stimulation evoked responses at shorter latency than surround whisker stimulation. In layers II – III and IV a bimodal distribution of cells according to latency to PW stimulation was found. Statistical analysis indicated the presence of two classes of cells in each of these layers:‘fast’units (latency 〈 15 ms) and 'slow’units (latency 〉15 ms). The great majority of cells in layers I, V and VI fired at latencies of 〉20 ms to PW stimulation. In general, stimulation of surround whiskers evoked a smaller response than PW stimulation. The fast cells of layer IV showed the greatest response to PW stimulation (mean = 1.78 spikes/100 ms poststimulus). Their firing was maximal during the 10–20 ms poststimulus epoch, while the slow layer IV cells fired maximally during the 20 – 30 ms poststimulus epoch. Surround inhibition occurred in all layers within the first 10 ms after stimulus onset, during which period the fast cells are the most active ones, and are thus likely to be responsible for the surround inhibition. This notion is supported by an analysis of spike duration that showed that eight of the ten cells with a thin spike (supposed to be GABAergic; McCormick et al., J. Neurophysiol., 54, 782 – 806, 1985), had PW latencies of 〈15 ms. We conclude that the activation of a barrel column is initially inhibitory in nature.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1460-9568.1993.tb00534.x
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  • 5
    Electronic Resource
    Electronic Resource
    Ultrastructure of giant and small thalamic terminals of cortical origin: a study of the projections from the barrel cortex in mice using Phaseolus vulgaris leuco-agglutinin (PHA-L) (1991)
    Springer
    Experimental brain research 87 (1991), S. 159-172 
    Details
    ISSN: 1432-1106
    Keywords: Corticothalamic projection ; Somatosensory system ; Barrel ; Phaseolus vulgaris ; leucoagglutinin ; Electron microscopy ; Mouse ; Synaptic glomerulus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary By means of tracing with the lectin Phaseolusvulgaris leucoagglutinin (PHA-L), we examined in the thalamus of the mouse, the axon terminals of fibers originating in the barrel cortex. Vibratome sections of the brain were subjected to PHA-L immunocytochemistry and processed for light and electron microscopy. We observed small (0.5–0.8 μm in diameter) varicosities of labeled fibers in the nucleus ventrobasalis (VB) and the nucleus posterior (PO) as well as labeled giant terminals (3–5 μm in diameter) in PO. The analysis involved examination of serial sections and computer-aided reconstruction of several terminals. The small varicosities in VB appear to be small axon terminals forming distinct asymmetric synapses with small dendritic profiles. Some labeled terminals are apposed to, but not synaptically related with, the cell bodies of neurons in VB that are retrogradely labeled with PHA-L. The small varicosities seen with the light microscope in PO are terminals forming asymmetric synapses with dendritic shafts. The giant terminals in PO appear as large, vesicle-filled profiles forming part of synaptic glomeruli, i.e. complexes of one corticothalamic terminal engulfing several excrescences of a single dendrite. A giant terminal forms several asymmetric synapses (about 8) with these excrescences, as well as numerous (up to 15) puncta adhaerentia. The glomeruli are enveloped in glial lamellae, and they are often found at the bifurcations of primary dendritic segments. We suggest that the small terminals in VB are in the service of feedback signalling from the barrel cortex to its principal thalamic relay nucleus; the functional importance of this projection may reside in increased spatio-temporal discrimination. We interpret the giant terminals in PO as elements serving feed-forward processing, allowing the barrel cortex to influence, via PO, parts of the motor pathway modulating the animal's ongoing behavior.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00228517
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  • 6
    Electronic Resource
    Electronic Resource
    Synapses on motoneuron dendrites in the brachial section of the frog spinal cord: a computer-aided electron microscopic study of cobalt-filled cells (1992)
    Springer
    Journal of neurocytology 21 (1992), S. 34-49 
    Details
    ISSN: 1573-7381
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Cobalt-labelled motoneuron dendrites of the frog spinal cord at the level of the second spinal nerve were photographed in the electron microscope from long series of ultrathin sections. Three-dimensional computer reconstructions of 120 dendrite segments were analysed. The samples were taken from two locations: proximal to cell body and distal, as defined in a transverse plane of the spinal cord. The dendrites showed highly irregular outlines with many 1–2 μm-long ‘thorns’ (on average 8.5 thorns per 100 μm2 of dendritic area). Taken together, the reconstructed dendrite segments from the proximal sites had a total length of about 250 μm; those from the distal locations, 180 μm. On all segments together there were 699 synapses. Nine percent of the synapses were on thorns, and many more close to their base on the dendritic shaft. The synapses were classified in four groups. One third of the synapses were asymmetric with spherical vesicles; one half were symmetric with spherical vesicles; and one tenth were symmetric with flattened vesicles. A fourth, small class of asymmetric synapses had dense-core vesicles. The area of the active zones was large for the asymmetric synapses (median value 0.20 μm2), and small for the symmetric ones (median value 0.10 μm2), and the difference was significant. On average, the areas of the active zones of the synapses on thin dendrites were larger than those of synapses on large calibre dendrites. About every 4 μm2 of dendritic area received one contact. There was a significant difference between the areas of the active zones of the synapses at the two locations. Moreover, the number per unit dendritic length was correlated with dendrite calibre. On average, the active zones covered more than 4% of the dendritic area; this value for thin dendrites was about twice as large as that of large calibre dendrites. We suggest that the larger active zones and the larger synaptic coverage of the thin dendrites compensate for the longer electrotonic distance of these synapses from the soma.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01206896
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  • 7
    Electronic Resource
    Electronic Resource
    A model system for a fluorometric biosensor using permeabilized Zymomonas mobilis or enzymes with protein confined dinucleotides (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 42 (1993), S. 387-393 
    Details
    ISSN: 0006-3592
    Keywords: biosensor ; glucose ; fructose ; gluconolactone ; sorbitol ; Zymomonas mobilis ; permeabilization ; NADPH ; fluorescence ; bioprocess monitoring ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Using permeabilized Zymomonas mobilis or glucose-fructose oxidoreductase isolated from this microorganism a model system for biosensors with a protein confined NADP(H) cofactor for the determination of glucose, fructose, gluconolactone, and sorbitol was developed. Either permeabilized microorganisms containing the oxidoreductase or the pure enzyme were confined via membrane separation in a small measuring chamber, that was integrated into a flow injection analysis system (FIA). The measuring principle was the monitoring of the NAD(P)H fluorescence, excited at 360 nm and measured at 450 nm. NADP(H), which is confined in the protein complex, was oxidized or reduced during the enzymatic reactions and the changes in the fluorescence intensity were related to the substrate concentration. The sensitivity of the system covered a range from 0.001 to 100 g/L of the analyte depending on substrate and operating conditions. The applicability of this model system for bioprocess monitoring was proved using samples from a Pseudomonas pseudoflava cultivation. © 1993 John Wiley & Sons, Inc.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260420317
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  • 8
    Electronic Resource
    Electronic Resource
    [Na · Triglyme]2[S(BH3)4]: Ein Salz des neuen Anions Tetrakis(boran)sulfat(2 - ) Kristallstruktur und theoretische Untersuchung der MolekülstrukturProfessor Heinrich Nöth zum 65. Geburtstage gewidmet (1993)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 619 (1993), S. 1353-1359 
    Details
    ISSN: 0044-2313
    Keywords: Bis[triglymesodium(1+)][Tetrakis(borane)sulfate(2-)], [Na · Triglyme]2[S(BH3)4] ; preparation ; crystal structure ; SCF calculations ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: [Na · Triglyme]2[S(BH3)4]: a Salt of the New Anion Tetrakis(borane)sulfate(2- ). Crystal Structure and Theoretical Investigation of the StructureNa[H3B-m̈2-S(B2H5)] 1 is produced by the reaction between NaSH and THF · BH3, under dehydrogenation. 1 is also formed as the first 11B-NMR-spectroscopically detectable reaction product by the reaction between anhydrous Na2S and THF · BH3. Adducts of BH3 with the S2- ion are not detectable in THF. The anion [S(BH3)4]2- can however be obtained, by the addition of NaBH4 to 1 in diglyme or triglyme respectively: [Na  -  Triglyme]2[S(BH3)4] 2. 2 crystallizes in the monoclinic space group P21/n (Nr. 14). Structural data of 1 and 2 have been calculated by SCF methods. The anion of 2 may be viewed either as an adduct of B2H6 with S2-, or as a bridge substituted thia derivative of B2H7-; furthermore the anion of 2 is isoelectronic and isostructural with the SO42- ion.
    Notes: Bei der Reaktion zwischen NaSH und THF · BH3 entsteht unter H2-Abspaltung Na[H3B-m̈2-S(B2H5)] 1. 1 entsteht auch als erstes 11B-NMR-spektroskopisch nachweisbares Reaktionsprodukt bei der Reaktion zwischen wasserfreiem Na2S und THF · BH3. Addukte von BH3 an das S2--Ion lassen sich in THF als Lösungsmittel nicht nachweisen. Das neue Anion [S(BH3)4]2- kann jedoch durch Addition von NaBH4 an 1 in Diglyme bzw. Triglyme erhalten werden: [Na · L]2[S(BH3)4] 2. 2 kristallisiert monoklin in der Raumgruppe P21/n (Nr. 14). Aus SCF-Rechnungen erhielten wir die Strukturparameter für 1 und 2. Das Anion von 2 kann sowohl als Addukt von B2H6 an S2- als auch als brückensubstituiertes Thia-Derivat des B2H7--Ions aufgefaßt werden; ferner ist es isoelektronisch und isostrukturell mit dem SO42-- Ion.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19936190806
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