Temat: Ab initio calculations - Katalog OPAC zbiorów

Skocz do pozycji: 1.

Tytuł:: Association of model peptides and dehydropeptides: N-acetyl-l-butyrine and (Z)-dehydrobutyrine N',N'-dimethylamides
Autorzy:: Broda, Małgorzata
Rzeszotarska, Barbara
Powiązania:: https://bibliotekanauki.pl/articles/1041295.pdf
Data publikacji:: 2006
Wydawca:: Polskie Towarzystwo Biochemiczne
Tematy:: ab initio/DFT calculations
hydrogen bonds
dimer
IR spectra
α,β-dehydroamino acids
Opis:: These comparative studies on the aggregation behaviour of Ac-(Z)-ΔAbu-NMe2 and Ac-L-Abu-NMe2 in carbon tetrachloride were performed by the analysis of their FTIR spectra and by theoretical calculations. The percentage of the monomeric form (α) decreased as concentration increased and this occurred to a higher degree for the (Z)-ΔAbu derivative than for its saturated analogue. The dimerization constant KD, calculated on the basis of the intensity of the monomer and associate bands in the νs(N-H) vibration region, is by three orders of magnitude larger for Ac-(Z)-ΔAbu-NMe2 than for Ac-L-Abu-NMe2. The obtained dimer geometries of the dehydro- compound were calculated by the B3LYP/6-31+G** method.
Źródło:: Acta Biochimica Polonica; 2006, 53, 1; 221-226
0001-527X
Pojawia się w:: Acta Biochimica Polonica
Dostawca treści:: Biblioteka Nauki

Artykuł

Skocz do pozycji: 2.

Tytuł:: Conformational properties of N-acetyl-L-alanine N',N'-dimethylamide.
Autorzy:: Siodłak, Dawid
Rzeszotarska, Barbara
Broda, Małgorzata
Powiązania:: https://bibliotekanauki.pl/articles/1043329.pdf
Data publikacji:: 2004
Wydawca:: Polskie Towarzystwo Biochemiczne
Tematy:: ab initio/DFT calculations
N-alkylpeptides
β-turns
alanine derivative
N',N'-dimethylamides
peptide design
Opis:: Ab initio/DFT analysis of the conformational properties of free Ac-Ala-NMe2 (N-acetyl-L-alanine-N',N'-dimethylamide) in terms of the N-H···O, N-H···N, C-H···O hydrogen bonds and Cδ+ = Oδ- dipole attractions was performed. The Ala residue combined with the C-terminal tertiary amide prefers an extended conformation and that characteristic of the (i + 1)th position of the βVIb turn. These can be easily remodelled into a structure compatible with the (i + 1)th position of the βII/βVIa turn. The residue has also the potential to adopt the conformation accommodated at both central positions of the βIII/βIII' turn or the (i + 1)th position of the βI/β'I turn.
Źródło:: Acta Biochimica Polonica; 2004, 51, 1; 137-143
0001-527X
Pojawia się w:: Acta Biochimica Polonica
Dostawca treści:: Biblioteka Nauki

Artykuł

Skocz do pozycji: 3.

Tytuł:: Conformational properties of N-acetyl-N-methyl-α,β-dehydroalanine N-methylamide
Autorzy:: Macedowska, Agnieszka
Siodłak, Dawid
Rzeszotarska, Barbara
Powiązania:: https://bibliotekanauki.pl/articles/1041296.pdf
Data publikacji:: 2006
Wydawca:: Polskie Towarzystwo Biochemiczne
Tematy:: ab initio/DFT calculations
N-alkylpeptides
cis-trans isomerisation
α,β-dehydroamino acids
peptide design
Opis:: The conformational properties of Ac-Δ(Me)Ala-NHMe (N-acetyl-N-methyl-α,β-dehydroalanine N'-methylamide), as the simplest model of N-methyl-α,β-dehydroamino acids, was examined with theoretical methods and in comparison with Ac-ΔAla-NHMe and Ac-ΔAla-NMe2. The N-terminal amide of the Δ(Me)Ala residue easily adopts the configuration cis and the torsion angles φ, ψ are highly flexible. The Δ(Me)Ala residue is a conformational flexibilizer as compared to the parent ΔAla, which is a conformational stiffener. This seems to be the reason why Δ(Me)Ala is found in small natural cyclic peptides, where it ensures the conformational flexibility necessary for biological action.
Źródło:: Acta Biochimica Polonica; 2006, 53, 1; 227-232
0001-527X
Pojawia się w:: Acta Biochimica Polonica
Dostawca treści:: Biblioteka Nauki

Artykuł

Skocz do pozycji: 4.

Tytuł:: Conformational investigation of α,β-dehydropeptides. XIII. Conformational properties of N-acetyl-α,β-dehydrovaline N',N'-dimethylamide.
Autorzy:: Siodłak, Dawid
Rzeszotarska, Barbara
Broda, Małgorzata
Kozioł, Anna
Kołodziejczyk, Edyta
Powiązania:: https://bibliotekanauki.pl/articles/1043332.pdf
Data publikacji:: 2004
Wydawca:: Polskie Towarzystwo Biochemiczne
Tematy:: ab initio/DFT calculations
N',N'-dimethylamides
X-ray crystallography
α,β-dehydroamino acids
peptide design
valine derivative
Opis:: The crystal structure of Ac-ΔVal-NMe2 (ΔVal = α,β-dehydrovaline) was determined by X-ray crystallography. The found angles φ = -60° and ψ = 125° correspond exactly to the respective values of the (i + 1)th residue in idealised β-turn II/VIa. Ab initio/DFT studies revealed that the molecule adopts the angle ψ restricted only to about |130°| and very readily attains the angle φ = about -50°. This is in line with its solid-state conformation. Taken together, these data suggest that the ΔVal residue combined with a C-terminal tertiary amide is a good candidate at the (i + 1)th position in a type II/VIa β-turn.
Źródło:: Acta Biochimica Polonica; 2004, 51, 1; 145-152
0001-527X
Pojawia się w:: Acta Biochimica Polonica
Dostawca treści:: Biblioteka Nauki

Artykuł

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