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21.
Effects of chemical, physical, and technological processes on the nature of food allergens 总被引:1,自引:0,他引:1
A review is presented of studies of different processing techniques and their effect on the allergenicity and antigenicity of certain allergenic foods. An overview of investigated technologies is given with regard to their impact on the protein structure and their potential application in the production of hypoallergenic foods. The use of physical processes (such as heating, high pressure, microparticulation, ultrafiltration, and irradiation), chemical processes (such as proteolysis, fermentation, and refining by extraction), and biotechnological approaches, as well as the effects of these processes on individual allergenic foods, are included. Additionally, the implications of food processing for food allergen analysis with respect to food safety assessment and industrial quality control are briefly discussed. 相似文献
22.
Oleinikova A Smolin N Brovchenko I Geiger A Winter R 《The journal of physical chemistry. B》2005,109(5):1988-1998
The formation of spanning hydrogen-bonded water networks on protein surfaces by a percolation transition is closely connected with the onset of their biological activity. To analyze the structure of the hydration water at this important threshold, we performed the first computer simulation study of the percolation transition of water in a model protein powder and on the surface of a single protein molecule. The formation of an infinite water network in the protein powder occurs as a 2D percolation transition at a critical hydration level, which is close to the values observed experimentally. The formation of a spanning 2D water network on a single rigid protein molecule can be described by adapting the cluster analysis of conventional percolation studies to the characterization of the connectivity of the hydration water on the surface of finite objects. Strong fluctuations of the surface water network are observed close to the percolation threshold. Our simulations also furnish a microscopic picture for understanding the specific values of the experimentally observed hydration levels, where different steps of increasing mobility in the hydrated powder are observed. 相似文献
23.
Roland Gemperlein 《Mikrochimica acta》1988,94(1-6):353-356
A continuously scanning Michelson interferometer was developed to modulate an intensive light source spectrally. The interferogram is used as a stimulus to investigate spectral sensitivities in insects and man. The FIS-method is fast and precise and shows many advantages which are partly based on the advantages of Fourier spectroscopy. The existing applications are summarized. 相似文献
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25.
Hetero- or homocoupling of protected 1,4-cis-diethynylated 1,5-anhydroglucitols leads to two isomeric cyclotrimers and to four isomeric cyclotetramers. The C3-symmetric cyciotrimer 31 , the C4-symmetric cyclotetramer 35 , and the D2-symmetric cyclotetramer 6 have been prepared before. We have now synthesized the C1-symmetric cyciotrimer 13 , and the C1- and the C2-symmetric cyclotetramers 22 and 27 , respectively. The cyclotrimer 13 was prepared by intramolecular, oxidative homocoupling and, alternatively, by a one-pot trimerization/cyclization of the monomer 36 (Schemes 1 and 5, resp.). Oxidative homocoupling was used for the cyclization of the tetramers 19 and 25 , leading to 22 and 27. The tetramer 19 was made by sequential Cadiot-Chod-kiewicz coupling (Scheme 2)and the tetramer 25 by a combination of a Cadiot-Chodkiewicz reaction and an intermolecular, oxidalive homocoupling (Scheme 3). The acetates 34 and 38 , corresponding to 35 and 27 , respectively, were also made by a one-pot dimerization/cyclization of the dimer 37 (Scheme 5). Intramolecular oxidative heterocoupling is also feasible and results in an alternative, more convenient synthesis of the acetylated cyclotrimer 30 and the acetylated cyclotetramer 34 (corresponding to 31 and 35 , resp.; Scheme 4). The solid-state conformation of the C4-symmetric cyclotetramer 34 corresponds well to the one predicted by force-field calculations. We compared the water-solubilities of the cyclotrimers 13 and 31 and the tetramers 6, 22, 27 , and 35 , their calculated conformations (MM3*), and the D -adenosine binding properties of the cyclotetramers 6, 27 , and 35 . 相似文献
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28.
3-Aminopyrazole was utilized as a starting material for the preparation of certain pyrazolo-[1,5-a]-1,3,5-triazines. 4-Chloro-2-methylthiopyrazolo[1,5-a]-1,3,5-triazine was prepared and used for studies of nucleophilic displacement reactions, and it has been found that both the chloro and methylthio groups may be displaced by nucleophiles. By modifications of these procedures we have prepared the adenine, hypoxanthine, and xanthine analogs of the pyrazolo-[1,5-a]-1,3,5-triazine ring system. Electrophilic substitution occurs in the 8-position of this ring system. The methyl group was introduced into the 4-position by a novel ring opening and ring closing of the 1,3,5-triazine ring. 相似文献
29.
Erich Metzger Roland Aeschimann Martin Egli Gaby Suter Ren Dohner Daniel Ammann Max Dobler Wilhelm Simon 《Helvetica chimica acta》1986,69(8):1821-1828
Lipophilic neutral carriers were synthesized which show Li+/Na+ selectivities of up to ca. 80 in highly lipophilic liquid membranes. The sensor membranes exhibit improved response times and increased lifetimes as compared to systems described earlier. They allow reliable measurements of Li+ in blood serum within the clinical concentration range. A 1:1 Li+/ionophore complex of one representative (N,N,N′,N′-tetracyclohexyl-5,5-dimethyl-3,7-dioxaazelaamide) has been prepared, and its structure was elucidated by X-ray analysis. 相似文献
30.
A facile synthesis of 2-formyl-1,8-naphthalenediol is reported. Its potential as a general precursor for the preparation of unsymmetrical multidentate chelating ligand systems based on 1,8-naphthalenediol is demonstrated by the synthesis of the dinucleating ligand L(4-)(H(4)L=N,N'-bis(2-(1,8-naphthalenediol)methylidene)propylenediamine). Reaction of H(4) L with copper acetate results in the formation of the unsymmetrical dinuclear Cu(II) complex [LCu(2)](3), which has been structurally characterized by single-crystal X-ray diffraction. One Cu(II) ion is coordinated by a N(2)O(2) compartment of L(4-) and the other Cu(II) ion is coordinated by an O(4) compartment of L(4-) while they are bridged by two aryloxide functions of L(4-). A dimerization of two molecules of 3 to a tetranuclear entity 3(2) occurs through formation of weak apical Cu--O interactions. Analysis of the temperature dependent magnetic susceptibility measurements (2--290 K) established a strong intradimer exchange coupling J(12)=-371 cm(-1). This strong superexchange interaction fits nicely in a magneto-structural correlation which has been established for dinuclear bis(phenoxide)-bridged Cu(II) complexes demonstrating the electronic equivalence of the aryloxides of a phenol and 1,8-naphthalenediol. 相似文献