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  • Chemistry  (2)
  • Cell & Developmental Biology  (1)
  • Molecular Biology  (1)
  • Phospholipase A2  (1)
  • Regeneration  (1)
  • 1
    Digitale Medien
    Digitale Medien
    Histochemical investigation of β-glucuronidase in culture cells and regenerated plants of Scutellaria baicalensis Georgi (2000)
    Springer
    Plant cell reports 19 (2000), S. 390-394 
    Details
    ISSN: 1432-203X
    Schlagwort(e): Key words Scutellaria ; Callus culture ; Regeneration ; β-Glucuronidase ; Distribution
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract  Strong activity of β-glucuronidase first appeared in the epidermal and glandular hair cells of leaf primordia regenerated from callus of Scutellaria baicalensis Georgi. Leaf primordia matured rapidly in culture to form shoots within 1 month in which both the mesophyll cells and the glandular hairs were deeply stained. Leaves predominantly accumulated β-glucuronidase in both glandular hair cells and mesophyll cells. β-Glucronidase activity in leaves was higher in the summer and decreased in the winter. The stem section collected in the summer had a different β-glucuronidase distribution pattern from that of the root in that in the former strong activity appeared in the periderm cells and collenchyma cells which was decreasingly dispersed into the phloem layer cells. In the winter, β-glucronidase activity decreased compared to that in summer. It can be argued that the distribution of β-glucuronidase in this plant is closely linked with the defense against pathogens: it is a starting key enzyme which may act together with the flavonoids, which play an important role as a proton donor for the detoxification metabolism of H2O2.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s002990050745
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    The conversion of ephedrine to methamphetamine and methamphetamine-like compounds during and prior to gas chromatographic/mass spectrometric analysis of CB and HFB derivatives (1992)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 21 (1992), S. 278-284 
    Details
    ISSN: 1052-9306
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Ephedrine and methamphetamine standards were separately derivatized with heptafluorobutyric anhydride (HFBA) and carbethoxyhexafluorobutyryl chloride (CB) and analyzed by full-scan gas chromatography/ion trap mass spectrometry with electron ionization (EI) and chemical ionization (CI). Using EI, a high-concentration ephedrine standard produced a total ion gas chromatogram containing several minor HFB derivatives in addition to ephedrine. One of these had the same retention time as the derivative of methamphetamine, while another eluted 3 s later. Both contained the same major mass fragmentation ions that could be erroneously used in targeted selected ion monitoring gas chromatographic/mass spectrometric analysis for methamphetamine. The full-scan EI and CI spectra showed that these derivatives were not methamphetamine. CI mass spectrometric studies of ephedrine scanning up to m/z 700 demonstrated that reaction with HFBA caused acylation of both the hydroxyl and secondary amino groups. The HFBA used in this study was contaminated with pentafluoropropionic anhydride and tri-fluoroacetic anhydride and produced mixtures of derivatives, some with retention times near or identical to that of methamphetamine. In contrast, CB derivatization of ephedrine produces a single methamphetamine-like compound that has the same retention time and mass spectra as methamphetamine, and is produced only when high gas chromatograph injector temperatures are used ( 〉 260°C). Collision-induced decomposition tandem mass spectrometric studies for the CB derivative verified that methamphetamine is produced from ephedrine at elevated GC injection port temperatures. In view of these findings, substance abuse testing for methamphetamine in urine must proceed with caution when ephedrine and other sympathomimetic amines are present. Definitive analyses can be accomplished by full-scan CI gas chromatographic/mass spectrometric analysis with HFB derivatives, or by lowering gas chromatograph injector temperatures with CB derivatives.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bms.1200210603
    Standort Signatur Erwartet Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Biosynthesis of prostaglandins by human spermatozoa in vitro and their role in acrosome reaction and fertilization (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 33 (1992), S. 303-306 
    Details
    ISSN: 1040-452X
    Schlagwort(e): Arachidonic acid ; Calcium ionophores ; Cyclooxygenase ; Cyclooxygenase inhibitors ; Lipoxygenase products ; Phospholipase A2 ; Thromboxanes ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie
    Notizen: Five homogenates of human sperm cells were separately incubated with [14C]arachidonic acid in the presence of reduced glutathione, L-tryptophan, and haematin as cofactors. The cyclooxygenase products of archidonic acid metabolism were extracted, separated, and measuréd for their radioactivity. The rate of formation of prostaglandin (PG)D2, PGE2, PGF2α, 6-keto PGF1α, and thromboxane (TX)B2 were 18.0 ± 1.11, 10.9 ± 0.68, 5.8 ± 0.21, 3.9 ± 0.13 and 6.6 ± 0.52 pmol/106 cells/min, respectively. These results are discussed in relation to the hypothesis that cyclooxygenase metabolites of certain polyunsaturated fatty acids play an important part in the sperm acrosome reaction and fertilization. © 1992 Wiley-Liss, Inc.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/mrd.1080330311
    Standort Signatur Erwartet Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    A new technique for detecting oxytocinase activity in electrophoresis gels (1992)
    Weinheim : Wiley-Blackwell
    Electrophoresis 13 (1992), S. 396-397 
    Details
    ISSN: 0173-0835
    Schlagwort(e): Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: A sensitive staining method for the detection of oxytocinase (EC 3.4.11.3) activity in electrophoresis gels has been described. The method is based on the enzymatic release of p-nitroaniline (PNA) from two specific synthetic oxytocinase sub-strates, S-benzyl-L-cysteine-p-nitroanilide (BCN) and L-leucine-p-nitroanilide (LN), respectively. The PNA is then diazotized with sodium nitrite and subsequently coupled to a chromogen, N-(1-naphtyl)-ethylenediamine dihydrochloride (NED) to produce a deep pink/magenta colored azo-dye at the site of oxytocinase activity.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/elps.1150130181
    Standort Signatur Erwartet Verfügbarkeit
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  • 5
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    Structure of a prehandover mammalian ribosomal SRP{middle dot}SRP receptor targeting complex (2018)
    American Association for the Advancement of Science (AAAS)
    In: Science
    Details
    Publikationsdatum: 2018-04-20
    Beschreibung: Signal recognition particle (SRP) targets proteins to the endoplasmic reticulum (ER). SRP recognizes the ribosome synthesizing a signal sequence and delivers it to the SRP receptor (SR) on the ER membrane followed by the transfer of the signal sequence to the translocon. Here, we present the cryo–electron microscopy structure of the mammalian translating ribosome in complex with SRP and SR in a conformation preceding signal sequence handover. The structure visualizes all eukaryotic-specific SRP and SR proteins and reveals their roles in stabilizing this conformation by forming a large protein assembly at the distal site of SRP RNA. We provide biochemical evidence that the guanosine triphosphate hydrolysis of SRP·SR is delayed at this stage, possibly to provide a time window for signal sequence handover to the translocon.
    Schlagwort(e): Molecular Biology
    Print ISSN: 0036-8075
    Digitale ISSN: 1095-9203
    Thema: Biologie , Chemie und Pharmazie , Geologie und Paläontologie , Informatik , Medizin , Allgemeine Naturwissenschaft , Physik
    Publiziert von American Association for the Advancement of Science (AAAS)
    Standort Signatur Erwartet Verfügbarkeit
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