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  • 1
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Peptide Science 4 (1998), S. 46-57 
    ISSN: 1075-2617
    Keywords: α-hydroxymethylserine peptides ; isopropylidene protecting group ; crystal structure ; peptide conformation ; peptide synthesis ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A synthetic methodology has been developed for peptide bond formation with α-hydroxmethylserine as the carboxyl or amino component and also for the preparation of homo-sequences. The key intermediate, O,O-protected α-hydroxymethylserine in the form of an isopropylidene derivative, is easily accessible and represents the first example of a heterocyclic Cα,α-disubstituted amino acid containing an 1,3-dioxane ring. The use of this intermediate facilitates protection of the sterically hindered amino and carboxyl groups and is advantageous for the coupling and deprotection steps. X-ray structure determination of Z-HmS(Ipr)-Ala-OMe revealed that the two crystallographically independent molecules present in the asymmetric unit adopt an S-shaped conformation. In the one molecule the achiral HmS(Ipr) residue has the torsion angle values (φ==61.4°,ψ=40.8°) in the left-handed helical region of the Ramachandran map, while in the second molecule the negative torsion angles (φ=-60.1°, ψ=-44.4°) are associated with the right-handed helix. © 1998 European Peptide Society and John Wiley & Sons, Ltd.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Publication Date: 2020-02-03
    Electronic ISSN: 2045-2322
    Topics: Natural Sciences in General
    Published by Springer Nature
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  • 3
    Publication Date: 2020-08-11
    Description: Widespread occurrence of ZnO nanoparticles in environment follows the growing number of applications either in technology or agriculture. The impact of five forms of nanoparticulate ZnO on copper, manganese and iron uptake by Pisum sativum L. cultivated in Hoagland solutions was investigated. Plants were collected after twelve days of zinc administration. Effect of bulk ZnO has also been studied. Initial zinc concentration was 100 mg L−1. Nanoparticles were characterized by the Transmission Electron Microscopy, Dynamic Light Scattering and Zeta potential measurements. Metal contents were analyzed using the Atomic Absorption Spectrometry with flame atomization for samples digested in a microwave closed system. Analysis of variance indicated that zinc species at either molecular or nanoscale levels altered Cu, Mn and Fe uptake and their further transport in pea plants. In particular, significant reduction of Mn and Fe combined with the Cu increase was observed. Additive interactions originated by nanoparticles affect the heavy metals uptake and indicate pollutants migration pathways in plants. Unfortunately, regulations for the plant cultivation were formulated when anthropogenic nanoparticles were not in common use. They underestimate complexity of metals interactions in either plant or habitat. Our results indicate that these additive interactions cannot be neglected and deserve further investigations.
    Electronic ISSN: 2045-2322
    Topics: Natural Sciences in General
    Published by Springer Nature
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  • 4
    Publication Date: 2021-10-11
    Description: Dandelion (Taraxacum officinale) yields active substances frequently used in herbal medicinal preparations. Its plantations are exposed to fungal plagues which pose a threat to herbal crops. The aim of this study was to evaluate the long time effects of a fungicide thiuram on dandelion growth and photosynthesis. Additionally, the manganese, iron, copper, zinc, cadmium, and lead uptake and transport were also investigated. Plants were cultivated under greenhouse conditions by the pot method in a universal flowering soil. The elements content in soil and plants were determined by the HR-CS FAAS spectrometer. Thiuram concentrations were established by the HPLC. Those analyses showed that almost 80% of thiuram decomposed within two weeks of its application. The photosynthesis indicators suggested, that plants were in good conditions and the fungicide supplementation facilitated plant growth. The latter could be prompted by thiuram acting as a sulfur rich chemical micro fertilizer. The hypothesis, that thiuram significantly affects heavy metals interactions in dandelion was proved by the one-way analysis of variance. Notable, metals uptake did not completely recover after fungicide decomposition for all investigated elements except iron We suggest to define this chemically induced, time-dependent heavy metals migrations in the soil–plant system as hysteresis of heavy metals uptake.
    Electronic ISSN: 2045-2322
    Topics: Natural Sciences in General
    Published by Springer Nature
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