Conformational preferences of β-sheet structures in cyclopropane-containing γ-peptidesElectronic supplementary information (ESI) available: The geometric parameters and strengths of inter-strand H-bonds in β-sheets of oligo-γ-peptides, and the deformation energies of each strand due to β-sheet formation. See DOI: 10.1039/c5nj00545k
The conformational preferences of β-sheets in oligo-γ-peptides composed of 2-(aminomethyl)cyclopropanecarboxylic acid (γAmc 3 ) with a cyclopropane constraint on the C α -C β bond were studied using density functional theory (DFT) methods in the gas phase and in solution (chloroform and water). Para...
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Main Authors | , , |
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Format | Journal Article |
Language | English |
Published |
02.06.2015
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Online Access | Get full text |
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Summary: | The conformational preferences of β-sheets in oligo-γ-peptides composed of 2-(aminomethyl)cyclopropanecarboxylic acid (γAmc
3
) with a cyclopropane constraint on the C
α
-C
β
bond were studied using density functional theory (DFT) methods in the gas phase and in solution (chloroform and water). Parallel β-sheets were preferred over the corresponding antiparallel β-sheets in the gas phase. The propensity to form parallel β-sheets increased as the length of the peptide sequence was increased. Parallel β-sheets had larger inter-strand N-H O H-bond energies, whereas antiparallel β-sheets had slightly favored C-H O energies and smaller deformation energies. Thus, the greater stability of parallel β-sheets can be ascribed to the formation of stronger N-H O H-bonds. Antiparallel β-sheets exhibited more favored solvation free energies than did the corresponding parallel β-sheets. Although parallel β-sheets were more stable than antiparallel β-sheets in chloroform, parallel and antiparallel β-sheets exhibited nearly similar stabilities for the tetrapeptide and hexapeptide in water. The greater importance of desolvation in parallel β-sheets compared with antiparallel β-sheets may be partially attributable to the formation of stronger inter-strand N-H O H-bonds in parallel β-sheets. DFT calculations supported the formation of parallel β-sheets for the tetrapeptide and hexapeptide in chloroform, consistent with experimental data for γAmc
3
-containing peptides that form parallel β-sheets in CDCl
3
. The conformational preferences of β-sheets determined here will provide useful information for understanding the conformational preferences of other oligo-γ-peptides with specific functions.
Oligo-γ-peptides based on 2-(aminomethyl)cyclopropanecarboxylic acid (γAmc
3
) with a cyclopropane constraint on the C
α
-C
β
bond preferentially formed parallel β-sheets rather than antiparallel β-sheets due to the stronger N-H O H-bonds in the parallel conformation. |
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Bibliography: | Electronic supplementary information (ESI) available: The geometric parameters and strengths of inter-strand H-bonds in β-sheets of oligo-γ-peptides, and the deformation energies of each strand due to β-sheet formation. See DOI 10.1039/c5nj00545k |
ISSN: | 1144-0546 1369-9261 |
DOI: | 10.1039/c5nj00545k |