The β-turn preferential solution conformation of a tetrapeptide containing an azaamino acid residue

H. J. Lee, Kihang Choi, I. A. Ahn, S. Ro, Ho Gyeom Jang, Y. S. Choi, K. B. Lee

Research output: Contribution to journalArticle

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Abstract

The global minimum energy conformation of an azapeptide model, For-Ala-azaAla-NH2 was predicted by ab initio calculation of the 3-21G and 6-31G* levels. The backbone torsion angle (φ1, ψ1, φ2, ψ2) of an azapeptide model appeared to be the β-turn conformation with a dihedral angle (-61°, 131°, 79°, 15°). This indicates that azaamino acid induces the β-turn motif regardless of the change of chain length by the addition of an amino acid in azapeptide when compared with the minimum energy conformation of For-azaAla-NH2. We designed and synthesized a tetrapeptide containing azaamino acid, Boc-Ala-Phe-azaLeu-Ala-OMe (1) to verify whether this β-turn conformation is still conserved in solution. The solution conformation of this azapeptide model was determined by using IR, NMR and molecular modeling techniques. The conformational behavior of this azapeptide was compared with that of the tetrapeptide, Boc-Ala-Phe-Leu-Ala-OMe (2), which was not associated with azaamino acid. The IR evidence of intramolecular H-bonding, the characteristic nuclear Overhauser enhancement (NOE) patterns, the temperature coefficients of amide protons and small solvent accessibility for the azapeptide 1 reveal that it favors the β-turn structure, whereas the peptide 2 forms extended structure in CDCl3 solution. The average structure of azapeptide 1 from a restrained molecular dynamics simulation indicated that the dihedral angles [(φ2, ψ2), (φ3, ψ3)] of Phe-azaLeu fragment in a model peptide, Boc-Ala-Phe-azaLeu-Ala-OMe were [(-60 ± 8°, 125 ± 24°), (88 ± 21°, 1 ± 4°)], and this implies that the intercalation of an azaamino acid residue in tetrapeptide induces the βII-turn conformation, and the increase of chain length by the addition of an amino acid in azapeptide constituents would not disrupt the backbone dihedral angle of β-turn conformation.

Original languageEnglish
Pages (from-to)43-54
Number of pages12
JournalJournal of Molecular Structure
Volume569
Issue number1-3
DOIs
Publication statusPublished - 2001 Jul 19

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Conformations
dihedral angle
acids
Acids
Dihedral angle
peptides
amino acids
Amino Acids
Peptides
Chain length
Molecular Dynamics Simulation
Amides
intercalation
amides
torsion
Protons
fragments
molecular dynamics
Molecular modeling
nuclear magnetic resonance

Keywords

  • β-turn
  • Azapeptide
  • IR
  • Molecular dynamics
  • NMR

ASJC Scopus subject areas

  • Structural Biology
  • Organic Chemistry
  • Physical and Theoretical Chemistry
  • Spectroscopy
  • Atomic and Molecular Physics, and Optics

Cite this

The β-turn preferential solution conformation of a tetrapeptide containing an azaamino acid residue. / Lee, H. J.; Choi, Kihang; Ahn, I. A.; Ro, S.; Jang, Ho Gyeom; Choi, Y. S.; Lee, K. B.

In: Journal of Molecular Structure, Vol. 569, No. 1-3, 19.07.2001, p. 43-54.

Research output: Contribution to journalArticle

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abstract = "The global minimum energy conformation of an azapeptide model, For-Ala-azaAla-NH2 was predicted by ab initio calculation of the 3-21G and 6-31G* levels. The backbone torsion angle (φ1, ψ1, φ2, ψ2) of an azapeptide model appeared to be the β-turn conformation with a dihedral angle (-61°, 131°, 79°, 15°). This indicates that azaamino acid induces the β-turn motif regardless of the change of chain length by the addition of an amino acid in azapeptide when compared with the minimum energy conformation of For-azaAla-NH2. We designed and synthesized a tetrapeptide containing azaamino acid, Boc-Ala-Phe-azaLeu-Ala-OMe (1) to verify whether this β-turn conformation is still conserved in solution. The solution conformation of this azapeptide model was determined by using IR, NMR and molecular modeling techniques. The conformational behavior of this azapeptide was compared with that of the tetrapeptide, Boc-Ala-Phe-Leu-Ala-OMe (2), which was not associated with azaamino acid. The IR evidence of intramolecular H-bonding, the characteristic nuclear Overhauser enhancement (NOE) patterns, the temperature coefficients of amide protons and small solvent accessibility for the azapeptide 1 reveal that it favors the β-turn structure, whereas the peptide 2 forms extended structure in CDCl3 solution. The average structure of azapeptide 1 from a restrained molecular dynamics simulation indicated that the dihedral angles [(φ2, ψ2), (φ3, ψ3)] of Phe-azaLeu fragment in a model peptide, Boc-Ala-Phe-azaLeu-Ala-OMe were [(-60 ± 8°, 125 ± 24°), (88 ± 21°, 1 ± 4°)], and this implies that the intercalation of an azaamino acid residue in tetrapeptide induces the βII-turn conformation, and the increase of chain length by the addition of an amino acid in azapeptide constituents would not disrupt the backbone dihedral angle of β-turn conformation.",
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AU - Choi, Y. S.

AU - Lee, K. B.

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N2 - The global minimum energy conformation of an azapeptide model, For-Ala-azaAla-NH2 was predicted by ab initio calculation of the 3-21G and 6-31G* levels. The backbone torsion angle (φ1, ψ1, φ2, ψ2) of an azapeptide model appeared to be the β-turn conformation with a dihedral angle (-61°, 131°, 79°, 15°). This indicates that azaamino acid induces the β-turn motif regardless of the change of chain length by the addition of an amino acid in azapeptide when compared with the minimum energy conformation of For-azaAla-NH2. We designed and synthesized a tetrapeptide containing azaamino acid, Boc-Ala-Phe-azaLeu-Ala-OMe (1) to verify whether this β-turn conformation is still conserved in solution. The solution conformation of this azapeptide model was determined by using IR, NMR and molecular modeling techniques. The conformational behavior of this azapeptide was compared with that of the tetrapeptide, Boc-Ala-Phe-Leu-Ala-OMe (2), which was not associated with azaamino acid. The IR evidence of intramolecular H-bonding, the characteristic nuclear Overhauser enhancement (NOE) patterns, the temperature coefficients of amide protons and small solvent accessibility for the azapeptide 1 reveal that it favors the β-turn structure, whereas the peptide 2 forms extended structure in CDCl3 solution. The average structure of azapeptide 1 from a restrained molecular dynamics simulation indicated that the dihedral angles [(φ2, ψ2), (φ3, ψ3)] of Phe-azaLeu fragment in a model peptide, Boc-Ala-Phe-azaLeu-Ala-OMe were [(-60 ± 8°, 125 ± 24°), (88 ± 21°, 1 ± 4°)], and this implies that the intercalation of an azaamino acid residue in tetrapeptide induces the βII-turn conformation, and the increase of chain length by the addition of an amino acid in azapeptide constituents would not disrupt the backbone dihedral angle of β-turn conformation.

AB - The global minimum energy conformation of an azapeptide model, For-Ala-azaAla-NH2 was predicted by ab initio calculation of the 3-21G and 6-31G* levels. The backbone torsion angle (φ1, ψ1, φ2, ψ2) of an azapeptide model appeared to be the β-turn conformation with a dihedral angle (-61°, 131°, 79°, 15°). This indicates that azaamino acid induces the β-turn motif regardless of the change of chain length by the addition of an amino acid in azapeptide when compared with the minimum energy conformation of For-azaAla-NH2. We designed and synthesized a tetrapeptide containing azaamino acid, Boc-Ala-Phe-azaLeu-Ala-OMe (1) to verify whether this β-turn conformation is still conserved in solution. The solution conformation of this azapeptide model was determined by using IR, NMR and molecular modeling techniques. The conformational behavior of this azapeptide was compared with that of the tetrapeptide, Boc-Ala-Phe-Leu-Ala-OMe (2), which was not associated with azaamino acid. The IR evidence of intramolecular H-bonding, the characteristic nuclear Overhauser enhancement (NOE) patterns, the temperature coefficients of amide protons and small solvent accessibility for the azapeptide 1 reveal that it favors the β-turn structure, whereas the peptide 2 forms extended structure in CDCl3 solution. The average structure of azapeptide 1 from a restrained molecular dynamics simulation indicated that the dihedral angles [(φ2, ψ2), (φ3, ψ3)] of Phe-azaLeu fragment in a model peptide, Boc-Ala-Phe-azaLeu-Ala-OMe were [(-60 ± 8°, 125 ± 24°), (88 ± 21°, 1 ± 4°)], and this implies that the intercalation of an azaamino acid residue in tetrapeptide induces the βII-turn conformation, and the increase of chain length by the addition of an amino acid in azapeptide constituents would not disrupt the backbone dihedral angle of β-turn conformation.

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