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  • Analytical Chemistry and Spectroscopy  (9)
  • Germination (seed)  (3)
  • 1
    Electronic Resource
    Electronic Resource
    Synthesis of the peptide-transport carrier of barley scutellum during the early stages of germination (1985)
    Springer
    Planta 164 (1985), S. 550-556 
    Details
    ISSN: 1432-2048
    Keywords: Germination (seed) ; Hordeum (peptide transport) ; Peptide transport ; Protein synthesis ; Scutellum ; Seed germination ; Thiol group
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Development of peptide-transport activity in the scutella of isolated barley (Hordeum vulgare l. cv. Maris Otter, Winter) embryos is shown to increase rapidly after about 15 h of imbibition, with the bulk of the transport activity being expressed by 24 h. This development is prevented by treatment of 15 h embryos with cycloheximide. Protein synthesis is found to increase in a closely related manner and also to be abolished by cycloheximide. Measurement of the incorporation of bound [35S]methionine by 15 to 21-h embryos indicates that de-novo protein synthesis during this period is greater in the scutellum than in the embryonic axis. Previous studies have shown that the peptide-transport system possesses essential dithiol groups, probably located at the substrate-binding site (Walker-Smith and Payne 1983 b, 1984b). Treatment of 15-h embryos with the non-penetrant thiol reagent p-chloromercuribenzene sulphonic acid did not affect development of peptide-transport activity during the following 6 h, whereas with 3-d embryos identical treatment inhibited uptake almost completely during a subsequent 6-h period. Radioautography revealed that amongst the proteins synthesised during this early phase of germination and labelled in vitro with [35S]methionine some are found within the epithelial plasmalemmae of the scutellum, which is the location of the peptide-transport carrier identified previously by externally labelling with a radioactive thiol reagent. The results provide evidence that protein(s) of the peptide-transport system are synthesised and inserted into the scutellum during early germination, allowing the system to play a major role in the nitrogen nutrition of the embryo.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00395974
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  • 2
    Electronic Resource
    Electronic Resource
    Characteristics of the protein carrier of the peptide-transport system in the scutellum of germinating barley embryos (1984)
    Springer
    Planta 162 (1984), S. 166-173 
    Details
    ISSN: 1432-2048
    Keywords: N-Ethylmalemide ; Germination (seed) ; Hordeum (embryo, peptide) ; Peptide transport ; Thiol group ; Transport carrier protein
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Through the use of the protein reagents N-ethylmaleimide, p-chloromercuribenzenesulphonic acid and phenylarsine oxide, it is shown that in the scutellum of the germinating barley embryo, the transport of peptides, but not the transport of amino acids or glucose is specifically thiol-dependent. Furthermore, these essential thiol groups are shown to exist as redox-sensitive, vicinal-dithiols that lie at the substrate-binding sites of the peptide-transport proteins. The binding of N-ethylmaleimide to these dithiols is shown to be very fast, matching the kinetics of inhibition of peptide transport by this reagent. A technique for the specific labelling of the dithiols with N-ethyl[2,3-14C]maleimide is described, which allows the carrier proteins to be visualized at the scutellar epithelium using radioautography and permits calculation of the approximate amount of peptide-transport protein present per scutellum. In related studies, the importance of arginyl and histidyl residues to both amino-acid and peptide transport is shown, although other residues, e.g. carboxyl ligands do not seem to be critically involved.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00410214
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  • 3
    Electronic Resource
    Electronic Resource
    Characteristics of the active transport of peptides and amino acids by germinating barley embryos (1984)
    Springer
    Planta 162 (1984), S. 159-165 
    Details
    ISSN: 1432-2048
    Keywords: Amino acid transport ; Germination (seed) ; Hordeum (peptide) ; Peptide transport ; Scutellum ; Storage protein mobilization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Use of two different assays involving either radioactively labelled substrates or a fluorescent-labelling procedure, gave good agreement for the rates of transport of peptides and amino acids into the scutellum of germinating grains of barley (Hordeum vulgare cv. Maris Otter, Winter). However, evidence was obtained for the enzymic decarboxylation of transpored substrate, which can cause underestimates of transport rates when using radioactively labelled substrates. The peptide Gly-Phe, was shown to be rapidly hydrolysed after uptake, and autoradiography of transported Gly-[U-14C]Phe indicated a rapid distribution of tracer, i.e. [U-14C] phenylalanine into the epithelium and sub-epithelial layers of the scutellum. The developmental patterns of transport activity indicate that peptide transport is more important nutritionally during the early stages of germination (1–3 d) whereas amino acids become relatively more important later (4–6 d). A range of amino acids is shown to be actively transported and several compete for uptake. At physiological concentrations, e.g. 2mM, transport of peptides and amino acids is inhibited about 80% by protonophore uncouplers, but at higher concentrations (10–100 mM) passive uptake predominates.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00410213
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  • 4
    Electronic Resource
    Electronic Resource
    Mass spectrometry in structural and stereochemical problems - CCXXII:For Part CCXXI, see K. Tomer and C. Djerassi, Org. Mass Spectrom. 6, 1285 (1972). Delineation of competing fragmentation pathways of complex molecules from a study of metastable ion transitions of deuterated derivatives (1973)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 7 (1973), S. 367-381 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Data on defocused metastable ions have been obtained for a series of structurally significant fragment ions in the mass spectra of the estrogenic steroid, estrone methyl ether and the alkaloid tropine. These data, in conjunction with measurements on defocused metastable ions in the mass spectra of isotopically labeled analogs and complete high resolution mass spectra provide important insights into the details of fragmentation processes, specifically: (a) an enumeration and determination of the frequent multiple origins of fragment ions in the mass spectra of such complex molecules, (b) specification of skeletal atoms lost and retained in concerted (one step) processes, and at each step of stepwise processes, leading to a particular fragment ion and (c) information on the relative contributions of concerted and stepwise processes resulting in the genesis of a given ion.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210070402
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  • 5
    Electronic Resource
    Electronic Resource
    The atomic number dependence of the X-ray continuum intensity and the practical calculation of background in energy dispersive electron microprobe analysis (1975)
    New York, NY [u.a.] : Wiley-Blackwell
    X-Ray Spectrometry 4 (1975), S. 149-156 
    Details
    ISSN: 0049-8246
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Computer fitting techniques have been used to derive a new expression for the relationship between X-ray continuum intensity and atomic number for a range of electron acelerating potentials up to 25 kV, continuum energies up to 10 keV and average atomic numbers up to thirty. A practical approach to background corrections in energy dispersive electron microprobe analysis, which utilizes this expression, is outlined. The procedure should lead to significant improvements in both accuracy and detection limits in this method of X-ray analysis.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/xrs.1300040311
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  • 6
    Electronic Resource
    Electronic Resource
    Window contamination of energy-dispersive detectors in electron microprobe analysis (1981)
    New York, NY [u.a.] : Wiley-Blackwell
    X-Ray Spectrometry 10 (1981), S. 78-81 
    Details
    ISSN: 0049-8246
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Oil film contamination of the Be window of a Si detector has been demonstrated using archival information on X-ray intensities from calibration standards acquired over a two and a half year period. Although cleaning the window with a solvent restores sensitivity for soft radiation, recontamination can be rapid unless a small heating device is placed close to the window. A mathematical correction is suggested which avoids significant analytical errors from the effect of any contamination which may be present. It can be applied automatically by data processing software using information from the calibration standard spectrum.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/xrs.1300100209
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  • 7
    Electronic Resource
    Electronic Resource
    High resolution mass spectrometry in molecular structure studies - V: The fragmentation of amaryllis alkaloids in the crinine seriesFor Part IV, see Ref. 1. (1973)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 7 (1973), S. 401-415 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: High resolution mass spectral fragmentation patterns of Amaryllidaceae alkaloids in the crinine series have been investigated as well as those of certain isotopically labeled derivatives. Attention is directed to the particular importance of employing entire high resolution mass spectra in attempting the elucidation of structural correlations in compounds which display few significant relative intensity variations in a complex fragmentation pattern.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210070405
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  • 8
    Electronic Resource
    Electronic Resource
    Complete 1H and 13C assignments of ractopamine hydrochloride using 2D and selective 1D NMR methods (1993)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 31 (1993), S. 283-286 
    Details
    ISSN: 0749-1581
    Keywords: Ractopamine ; Long-range selective proton decoupling ; NMR assignments ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The 1H and 13C NMR resonances for ractopamine hydrochloride have been assigned. H,H-COSY and H,C-COSY were used to assign the aliphatic moiety of the molecule and to correlate protons and carbons on the same ring system. Long-range selective proton decoupling (LSPD) experiments were used to assign quaternary carbons and to distinguish the two ring systems.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1260310314
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  • 9
    Electronic Resource
    Electronic Resource
    Measurement of oxygen K absorption spectra using an electron microprobe (1975)
    New York, NY [u.a.] : Wiley-Blackwell
    X-Ray Spectrometry 4 (1975), S. 65-70 
    Details
    ISSN: 0049-8246
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: A technique is outlined which use the electron microprobe to obtain X-ray absorption spectra, by photon absorption, in the long wavelength region. Spectra are presented for SiO, SiO2, rectorite, talc, vermiculite, V2O5, Cr2O3, Fe2O3, maghemite, Mylar and collodion. For all compounds the main absorption edge is near to 536 eV, which is significantly higher than core binding measured in ESCA studies. The transition metal oxides and organic films show a sharp absorption line near 531 eV in addition to the above edge. This absorption line is very close in energy to the anomalous peak observed in the oxygen K emission spectra when using KAP or other acid phthalate crystals and it seems likely that the two phenomena are associated.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/xrs.1300040206
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  • 10
    Electronic Resource
    Electronic Resource
    Kβ/Kα intensity ratios for elements of atomic number 20 to 30 (1974)
    New York, NY [u.a.] : Wiley-Blackwell
    X-Ray Spectrometry 3 (1974), S. 149-150 
    Details
    ISSN: 0049-8246
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Twenty-five new measurements of Kβ/Kα X-ray intensity ratios for elements in the atomic number range 20 to 30 confirm other recent evidence that the variation with atomic number in this region is much less than previously thought, but there is still some disagreement for atomic numbers above 27. A table of recommended values is given.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/xrs.1300030405
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