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1

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

100%

Siodłak D., Rzeszotarska B., Broda M. A.

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vol. 51

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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.

2

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

100%

Macedowska A., Siodłak D., Rzeszotarska B.

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2006

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vol. 53

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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.

3

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

88%

Siodłak D., Rzeszotarska B., Broda M. A., Kozioł A. E., Kołodziejczyk E.

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vol. 51

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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.

4

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

88%

Siodłak D., Broda M. A., Rzeszotarska B., Kozioł A. E., Dybała I.

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2001

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vol. 48

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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.

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4 Acta Biochimica Polonica

1 2006

2 2004

1 2001

4 Rzeszotarska B.

4 Siodłak D.

3 Broda M. A.

2 Kozioł A. E.

1 Dybała I.

1 Kołodziejczyk E.

1 Macedowska A.

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

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

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

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