Full-text resources of PSJD and other databases are now available in the new Library of Science.
Visit https://bibliotekanauki.pl
Preferences help
Polish version English version Language
enabled [disable] Abstract
Number of results

Results found: 8

Number of results on page
first rewind previous Page / 1 next fast forward last

Search results

help Sort By:

help Limit search:
first rewind previous Page / 1 next fast forward last
1
Content available remote

Association of model peptides and dehydropeptides: N-acetyl-l-butyrine and (Z)-dehydrobutyrine N',N'-dimethylamides

100%
Broda M. A., Rzeszotarska B.
|
2006
|
vol. 53
|
issue 1
221-226
EN
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.
2
Content available remote

Conformational properties of N-acetyl-L-alanine N',N'-dimethylamide.

81%
Siodłak D., Rzeszotarska B., Broda M. A.
|
|
vol. 51
|
issue 1
137-143
EN
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.
3
Content available remote

Acetylation of methyl 5-amino-1H-[1,2,4]triazole-3-carboxylate

81%
Dżygiel A., MAsiukiewicz E., Rzeszotarska B.
|
2001
|
vol. 48
|
issue 4
1169-1173
EN
Acetylation with acetic anhydride of methyl 5-amino-1H-[1,2,4]triazole-3-carboxylate, one of the hetareneamino acids, was studied using HPLC,1H NMR, FTIR and GC-MS. The compound has a significantly decreased susceptibility to acetylation compared to 5-amino-1H-[1,2,4]triazole itself. Two isomeric diacetylated products were found.
4
Content available remote

Conformational properties of N-acetyl-N-methyl-α,β-dehydroalanine N'-methylamide

81%
Macedowska A., Siodłak D., Rzeszotarska B.
|
2006
|
vol. 53
|
issue 1
227-232
EN
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.
5
Content available remote

Conformational investigation of α,β-dehydropeptides. XIII. Conformational properties of N-acetyl-α,β-dehydrovaline N',N'-dimethylamide.

71%
Siodłak D., Rzeszotarska B., Broda M. A., Kozioł A. E., Kołodziejczyk E.
|
|
vol. 51
|
issue 1
145-152
EN
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.
6
Content available remote

Conformational properties of N',N'-dimethylamides of N-acetyldehydroalanine and N-acetyl-(Z)-dehydropheny-alanine.

71%
Siodłak D., Broda M. A., Rzeszotarska B., Kozioł A. E., Dybała I.
|
2001
|
vol. 48
|
issue 4
1179-1183
EN
Conformational preferences of Ac-ΔAla-NMe2 and Ac-(Z)-ΔPhe-NMe2 were studied and compared with those of their monomethyl counterparts as well as with those of their saturated analogues. X-Ray data and energy calculations revealed a highly conservative conformation of the dehydro dimethylamides, which is located in a high-energy region of the Ramachandran map.
7
Content available remote

Sulfamide antifolates inhibiting thymidylate synthase: synthesis, enzyme inhibition and cytotoxicity.

61%
Pawełczak K., Makowski M., Kempny M., Dzik J. M., Gołos B., Rode W., Rzeszotarska B.
|
2002
|
vol. 49
|
issue 2
407-420
EN
Synthesis and biological evaluation are described of seven new analogues (3-9) of two potent thymidylate synthase inhibitors, 10-propargyl-5,8-dideazafolate (1) and its 2-methyl-2-deamino congener ICI 198583 (2). While the new compunds 3 and 4 were analogues of 1 and 2, respectively, containing a p-aminobenzenesulfonyl residue in place of the p-aminobenzoic acid residue, the remaining 5 new compounds were analogues of 4 with the L-glutamic acid residue replaced by glycine (5), L-valine (6), L-alanine (7), L-phenylglycine (8) or L-norvaline (9). The new analogues were tested as inhibitors of thymidylate synthases isolated from tumour (Ehrlich carcinoma), parasite (Hymenolepis diminuta) and normal tissue (regenerating rat liver) and found to be weaker inhibitors than the parent 10-propargyl-5,8-dideazafolic acid. Selected new analogues, tested as inhibitors of growth of mouse leukemia L 5178Y cells, were less potent than the parent 10-propargyl-5,8-dideazafolic acid. Substitution of the glutamyl residue in compound 4 with l-norvaline (9) resulted in only a 5-fold stronger thymidylate synthase inhibitor, but a 40-fold weaker cell growth inhibitor.
8
Content available remote

Synthesis and biological activity of Nα-[4-[N-[(3,4-dihydro-2-methyl-4-oxo-6-quinazolinyl)methyl]-N-propargylamino]phenyl-acetyl]-L-glutamic acid.

52%
Kusakiewicz-Dawid A., Bugaj M., Dzik J. M., Gołos B., Wińska P., Pawełczak K., Rzeszotarska B., Rode W.
|
2002
|
vol. 49
|
issue 1
197-202
EN
2-Deamino-2-methyl-N10-propargyl-5,8-dideazafolic acid (ICI 198583) is a potent inhibitor of thymidylate synthase. Its analogue, Nα-[4-[N-[(3,4-dihydro-2-methyl-4-oxo-6-quinazolinyl)methyl]-N-propargylamino]phenylacetyl]-L-glutamic acid, containing p-aminophenylacetic acid residue substituting p-aminobenzoic acid residue, was synthesized. The new analogue exhibited a moderately potent thymidylate synthase inhibition, of linear mixed type vs. the cofactor, N5,10 -methylenetetrahydrofolate. The Ki value of 0.34 μM, determined with a purified recombinant rat hepatoma enzyme, was about 30-fold higher than that reported for inhibition of thymidylate synthase from mouse leukemia L1210 cells by ICI 198583 (Hughes et al., 1990, J. Med. Chem. 33, 3060). Growth of mouse leukemia L5178Y cells was inhibited by the analogue (IC50 = 1.26 μM) 180-fold weaker than by ICI 198583 (IC50 = 6.9 μM).
first rewind previous Page / 1 next fast forward last
JavaScript is turned off in your web browser. Turn it on to take full advantage of this site, then refresh the page.