Peptide models XX. Aromatic side-chain - Backbone interaction in phenylalanine-containing diamide model system. A systematic search for the identification of all the ab initio conformers of N-formyl-L-phenylalanine- amide

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Abstract

Phenylalanine is the simplest among the four natural amino acid residues that have aromatic side chains. The ab initio conformational analysis performed at the RHF/3-21G level on a phenylalanine-containing diamide model system (N-Formyl-L-Phe-NH2) revealed 19 different structures. Single-point energy calculations were performed using RHF/6-31+G* and DFT(B3LYP)/6- 311++G** levels for all conformers. The inverse (γ(L)) and the normal (γ(D)) gamma turn, the extended (β(L)), the left-handed helical (α(D) [φ ≃ +60°, Ψ ≃ +60°]), and the inverse polyproline II (e(D) [φ ≃ 60°, Ψ ≃ 180°]) backbone conformers each have three (g+, a, and g-) side-chain (χ1) rotamers. The δ(L) [φ ≃ 240°, Ψ ≃ 60°] and the δ(D) [φ ≃ 180°, Ψ ≃ -60°] type main-chain conformers have only two side-chain orientations, respectively. No minima have been found for the conformational building unit of the right-handed helical (α(L) [φ ≃ -60°, Ψ ≃ -60°]) and for the polyproline II (ε(L) [φ ≃ -60°, Ψ ≃ 180°]) structures. The present ab initio conformational analysis for For-L-Phe-NH2 is a unique example in which a systematic and complete conformational set was established for a diamide system with an aromatic side chain. Analytic vibrational frequency calculations were established for all stationary points found as minima on the potential energy surface. These data may be used in the future as reference conformers in more detailed vibrational and (or) chemical shielding calculations or during the structural analysis of peptides and proteins by X-ray or NMR techniques.

Original languageEnglish
Pages (from-to)1120-1130
Number of pages11
JournalCanadian Journal of Chemistry
Volume75
Issue number8
Publication statusPublished - Aug 1997

Fingerprint

Diamide
Phenylalanine
Amides
Peptides
Identification (control systems)
Potential energy surfaces
Vibrational spectra
Discrete Fourier transforms
Structural analysis
Shielding
Amino acids
Nuclear magnetic resonance
Proteins
Amino Acids
X rays
phenylalanine amide
polyproline

Keywords

  • Ab initio peptide conformers
  • All RHF/3-21G structures of For-L-Phe- NH
  • Backbone - side-chain interaction in phenylalanine-containing peptide models

ASJC Scopus subject areas

  • Chemistry(all)

Cite this

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title = "Peptide models XX. Aromatic side-chain - Backbone interaction in phenylalanine-containing diamide model system. A systematic search for the identification of all the ab initio conformers of N-formyl-L-phenylalanine- amide",
abstract = "Phenylalanine is the simplest among the four natural amino acid residues that have aromatic side chains. The ab initio conformational analysis performed at the RHF/3-21G level on a phenylalanine-containing diamide model system (N-Formyl-L-Phe-NH2) revealed 19 different structures. Single-point energy calculations were performed using RHF/6-31+G* and DFT(B3LYP)/6- 311++G** levels for all conformers. The inverse (γ(L)) and the normal (γ(D)) gamma turn, the extended (β(L)), the left-handed helical (α(D) [φ ≃ +60°, Ψ ≃ +60°]), and the inverse polyproline II (e(D) [φ ≃ 60°, Ψ ≃ 180°]) backbone conformers each have three (g+, a, and g-) side-chain (χ1) rotamers. The δ(L) [φ ≃ 240°, Ψ ≃ 60°] and the δ(D) [φ ≃ 180°, Ψ ≃ -60°] type main-chain conformers have only two side-chain orientations, respectively. No minima have been found for the conformational building unit of the right-handed helical (α(L) [φ ≃ -60°, Ψ ≃ -60°]) and for the polyproline II (ε(L) [φ ≃ -60°, Ψ ≃ 180°]) structures. The present ab initio conformational analysis for For-L-Phe-NH2 is a unique example in which a systematic and complete conformational set was established for a diamide system with an aromatic side chain. Analytic vibrational frequency calculations were established for all stationary points found as minima on the potential energy surface. These data may be used in the future as reference conformers in more detailed vibrational and (or) chemical shielding calculations or during the structural analysis of peptides and proteins by X-ray or NMR techniques.",
keywords = "Ab initio peptide conformers, All RHF/3-21G structures of For-L-Phe- NH, Backbone - side-chain interaction in phenylalanine-containing peptide models",
author = "A. Perczel and O. Farkas and A. Cs{\'a}sz{\'a}r and I. Csizmadia",
year = "1997",
month = "8",
language = "English",
volume = "75",
pages = "1120--1130",
journal = "Canadian Journal of Chemistry",
issn = "0008-4042",
publisher = "National Research Council of Canada",
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T1 - Peptide models XX. Aromatic side-chain - Backbone interaction in phenylalanine-containing diamide model system. A systematic search for the identification of all the ab initio conformers of N-formyl-L-phenylalanine- amide

AU - Perczel, A.

AU - Farkas, O.

AU - Császár, A.

AU - Csizmadia, I.

PY - 1997/8

Y1 - 1997/8

N2 - Phenylalanine is the simplest among the four natural amino acid residues that have aromatic side chains. The ab initio conformational analysis performed at the RHF/3-21G level on a phenylalanine-containing diamide model system (N-Formyl-L-Phe-NH2) revealed 19 different structures. Single-point energy calculations were performed using RHF/6-31+G* and DFT(B3LYP)/6- 311++G** levels for all conformers. The inverse (γ(L)) and the normal (γ(D)) gamma turn, the extended (β(L)), the left-handed helical (α(D) [φ ≃ +60°, Ψ ≃ +60°]), and the inverse polyproline II (e(D) [φ ≃ 60°, Ψ ≃ 180°]) backbone conformers each have three (g+, a, and g-) side-chain (χ1) rotamers. The δ(L) [φ ≃ 240°, Ψ ≃ 60°] and the δ(D) [φ ≃ 180°, Ψ ≃ -60°] type main-chain conformers have only two side-chain orientations, respectively. No minima have been found for the conformational building unit of the right-handed helical (α(L) [φ ≃ -60°, Ψ ≃ -60°]) and for the polyproline II (ε(L) [φ ≃ -60°, Ψ ≃ 180°]) structures. The present ab initio conformational analysis for For-L-Phe-NH2 is a unique example in which a systematic and complete conformational set was established for a diamide system with an aromatic side chain. Analytic vibrational frequency calculations were established for all stationary points found as minima on the potential energy surface. These data may be used in the future as reference conformers in more detailed vibrational and (or) chemical shielding calculations or during the structural analysis of peptides and proteins by X-ray or NMR techniques.

AB - Phenylalanine is the simplest among the four natural amino acid residues that have aromatic side chains. The ab initio conformational analysis performed at the RHF/3-21G level on a phenylalanine-containing diamide model system (N-Formyl-L-Phe-NH2) revealed 19 different structures. Single-point energy calculations were performed using RHF/6-31+G* and DFT(B3LYP)/6- 311++G** levels for all conformers. The inverse (γ(L)) and the normal (γ(D)) gamma turn, the extended (β(L)), the left-handed helical (α(D) [φ ≃ +60°, Ψ ≃ +60°]), and the inverse polyproline II (e(D) [φ ≃ 60°, Ψ ≃ 180°]) backbone conformers each have three (g+, a, and g-) side-chain (χ1) rotamers. The δ(L) [φ ≃ 240°, Ψ ≃ 60°] and the δ(D) [φ ≃ 180°, Ψ ≃ -60°] type main-chain conformers have only two side-chain orientations, respectively. No minima have been found for the conformational building unit of the right-handed helical (α(L) [φ ≃ -60°, Ψ ≃ -60°]) and for the polyproline II (ε(L) [φ ≃ -60°, Ψ ≃ 180°]) structures. The present ab initio conformational analysis for For-L-Phe-NH2 is a unique example in which a systematic and complete conformational set was established for a diamide system with an aromatic side chain. Analytic vibrational frequency calculations were established for all stationary points found as minima on the potential energy surface. These data may be used in the future as reference conformers in more detailed vibrational and (or) chemical shielding calculations or during the structural analysis of peptides and proteins by X-ray or NMR techniques.

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KW - All RHF/3-21G structures of For-L-Phe- NH

KW - Backbone - side-chain interaction in phenylalanine-containing peptide models

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