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Wyszukujesz frazę "amides" wg kryterium: Temat


Wyświetlanie 1-3 z 3
Tytuł:
Preferential solvation of amides by methanol - a comparison of molecular dynamics calculations with the experimental data
Autorzy:
Zielkiewicz, J.
Powiązania:
https://bibliotekanauki.pl/articles/1965827.pdf
Data publikacji:
2001
Wydawca:
Politechnika Gdańska
Tematy:
amides
alcohols
preferential solvation
Kirkwood-Buff integrals
molecular dynamics simulations
Opis:
Using the Kirkwood-Buff theory of solutions, the preferential solvation of the N-methylacet-amide (NMA), N-methylformamide, (NMF), and N,N-dimethylformamide, (DMF), molecule has been investigated in the binary {amide+methanol} mixtures at 313.15 K. Moreover, for the {amide+methanol} mixtures, where amide = NMF, DMF, and NMA, the molecular dynamics calculations at xamide=0.518 were performed. From the obtained molecule-molecule radial distribution functions, (rdf), and atom-atom rdf, it was possible to estimate the local mole fractions around the amide molecule, the orientation effects of molecules within the solvation shell, and a possibility of the formation of complexes. The general picture obtained from analysis of the molecular dynamics results is consistent with the deductions derived from thermodynamic data.
Źródło:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2001, 5, 3; 317-329
1428-6394
Pojawia się w:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Molecular models in chemistry education at university and upper secondary school - structure of amides
Modele molekularne w nauczaniu chemii w szkole średniej i wyższej - struktura amidów
Autorzy:
Kolář, Karel
Doležal, Rafael
Karásková, Natálie
Maltsevskaya, Nadezhda V.
Křížková, Šárka
Powiązania:
https://bibliotekanauki.pl/articles/106668.pdf
Data publikacji:
2019
Wydawca:
Towarzystwo Chemii i Inżynierii Ekologicznej
Tematy:
acidity
amides
basicity
electrostatic potential
molecular models
kwasowość
amidy
zasadowość
potencjał elektrostatyczny
modele molekularne
Opis:
Molecular models derived from results of quantum-chemical calculations present an important category of didactic instruments in chemistry education in upper secondary school and, particularly, at university. These models can be used especially as tools for supporting the students’ understanding by visual learning, which can adequately address complexity of many chemical topics, incorporate appropriate didactic principles, as well as utilize the benefits brought up by the actual information technology. The proposed molecular models are non-trivial examples of didactic application of computational chemistry techniques in illustration of electron interactions in amidic group, namely the interaction of the free electron pair on the nitrogen atom with the carbonyl group and also the interaction of atoms in the amide group with other surrounding atoms in the molecule. By these molecular models it is possible to explain acid-base properties of amides applying knowledge of electron density distribution in the molecules and the resulting electrostatic potential. Presentation of the structure and properties of the amides within education is important also for the reason that amidic functions are involved in many important natural substances (e.g. proteins, peptides, nucleic acids or alkaloids), synthetic macromolecular substances (e.g. Silon) or pharmaceutical preparations (e.g. paracetamol). Molecular models then serve to support better understanding of the structure of these substances and, in relation to it, their properties.
Źródło:
Chemistry-Didactics-Ecology-Metrology; 2019, 24, 1-2; 45-51
2084-4506
Pojawia się w:
Chemistry-Didactics-Ecology-Metrology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Cyclic enkephalin-deltorphin hybrids containing a carbonyl bridge: structure and opioid activity
Autorzy:
Ciszewska, Małgorzata
Ruszczyńska, Katarzyna
Oleszczuk, Marta
Chung, Nga
Witkowska, Ewa
Schiller, Peter
Wójcik, Jacek
Izdebski, Jan
Powiązania:
https://bibliotekanauki.pl/articles/1039922.pdf
Data publikacji:
2011
Wydawca:
Polskie Towarzystwo Biochemiczne
Tematy:
cyclic opioid peptides
conformation
NMR
N-(ureidoethyl)amides
side-chain to side-chain cyclization
structure-activity relationship
Opis:
Six hybrid N-ureidoethylamides of octapeptides in which an N-terminal cyclic structure related to enkephalin was elongated by a C-terminal fragment of deltorphin were synthesized on MBHA resin. The synthetic procedure involved deprotection of Boc groups with HCl/dioxane and cleavage of the peptide resin with 45 % TFA in DCM. d-Lys and d-Orn were incorporated in position 2, and Lys, Orn, Dab, or Dap in position 5. The side chains of the dibasic amino function were protected with the Fmoc group. This protection was removed by treatment with 55 % piperidine in DMF, and cyclization was achieved by treatment with bis-(4-nitrophenyl)carbonate. Using various combinations of dibasic amino acids, peptides containing a 17-, 18-, 19- or 20-membered ring structure were obtained. The peptides were tested in the guinea-pig ileum (GPI) and mouse vas deferens (MVD) assays. Diverse opioid activities were observed, depending on the size of the ring. Extension of the enkephalin sequence at the C-terminus by a deltorphin fragment resulted in a change of receptor selectivity in favor of the δ receptor. The conformational propensities of selected peptides were determined using the EDMC method in conjunction with data derived from NMR experiments carried out in water. This approach allowed proper examination of the dynamical behavior of these small peptides. The results were compared with those obtained earlier with corresponding N-(ureidoethyl)pentapeptide amides.
Źródło:
Acta Biochimica Polonica; 2011, 58, 2; 225-230
0001-527X
Pojawia się w:
Acta Biochimica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-3 z 3

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