Conformers of gaseous threonine

Tamas Szidarovszky, G. Czakó, A. Császár

Research output: Contribution to journalArticle

32 Citations (Scopus)

Abstract

Following an extensive search on the potential energy surfaces (PES) of the natural amino acid L-threonine (Thr) and its allotropic form L-allo-threonine (aThr), 56 and 61 conformers of Thr and aThr, respectively, have been located with the help of density functional theory (DFT). Accurate structures, relative energies, rotational as well as quartic and sextic centrifugal distortion constants, dipole moments, 14N nuclear quadrupole coupling constants, anharmonic vibrational frequencies and double-harmonic infrared intensities have been determined from ab initio electronic structure calculations for the five most stable Thr and aThr conformers. The global minimum, Thr-I, has a cyclic triple H-bond motif with strong OH N, C=O HO, and a weaker NH OH H-bond, where the latter two involves the side chain OH, and an energetically unfavourable trans-COOH arrangement. The best relative energies of the conformers, accurate within 1 kJ mol-1, have been determined through the first-principles composite focal-point analysis (FPA) approach. There are four and three conformers of Thr and aThr, respectively, within a relative energy of 5 kJ mol-1. Similarly to other amino acids investigated, lower levels of electronic structure theory, especially the Hartree-Fock level, are unable to determine the correct relative energies of the conformers. The rotational, the quartic and sextic centrifugal distortion, and the 14N nuclear quadrupole coupling constants as well as the anharmonic vibrational fundamentals and double-harmonic infrared intensities, all determined using DFT, should aid identification and characterization of the conformers of threonine and allo-threonine by rotational and vibrational spectroscopies, respectively.

Original languageEnglish
Pages (from-to)761-775
Number of pages15
JournalMolecular Physics
Volume107
Issue number8-12
DOIs
Publication statusPublished - Jan 2009

Fingerprint

Threonine
amino acids
quadrupoles
density functional theory
electronic structure
harmonics
energy
dipole moments
potential energy
Electronic structure
Density functional theory
composite materials
Infrared radiation
L Forms
Amino Acids
spectroscopy
Vibrational spectroscopy
Potential energy surfaces
Dipole moment
Vibrational spectra

Keywords

  • Ab initio calculations
  • Amino acids
  • Conformational analysis
  • Focal-point analysis
  • Neutral L-allo-threonine
  • Neutral L-threonine
  • Structure elucidation

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Condensed Matter Physics
  • Biophysics
  • Molecular Biology

Cite this

Conformers of gaseous threonine. / Szidarovszky, Tamas; Czakó, G.; Császár, A.

In: Molecular Physics, Vol. 107, No. 8-12, 01.2009, p. 761-775.

Research output: Contribution to journalArticle

Szidarovszky, Tamas ; Czakó, G. ; Császár, A. / Conformers of gaseous threonine. In: Molecular Physics. 2009 ; Vol. 107, No. 8-12. pp. 761-775.
@article{b4adaf93abf742858e604e07b7e8d321,
title = "Conformers of gaseous threonine",
abstract = "Following an extensive search on the potential energy surfaces (PES) of the natural amino acid L-threonine (Thr) and its allotropic form L-allo-threonine (aThr), 56 and 61 conformers of Thr and aThr, respectively, have been located with the help of density functional theory (DFT). Accurate structures, relative energies, rotational as well as quartic and sextic centrifugal distortion constants, dipole moments, 14N nuclear quadrupole coupling constants, anharmonic vibrational frequencies and double-harmonic infrared intensities have been determined from ab initio electronic structure calculations for the five most stable Thr and aThr conformers. The global minimum, Thr-I, has a cyclic triple H-bond motif with strong OH N, C=O HO, and a weaker NH OH H-bond, where the latter two involves the side chain OH, and an energetically unfavourable trans-COOH arrangement. The best relative energies of the conformers, accurate within 1 kJ mol-1, have been determined through the first-principles composite focal-point analysis (FPA) approach. There are four and three conformers of Thr and aThr, respectively, within a relative energy of 5 kJ mol-1. Similarly to other amino acids investigated, lower levels of electronic structure theory, especially the Hartree-Fock level, are unable to determine the correct relative energies of the conformers. The rotational, the quartic and sextic centrifugal distortion, and the 14N nuclear quadrupole coupling constants as well as the anharmonic vibrational fundamentals and double-harmonic infrared intensities, all determined using DFT, should aid identification and characterization of the conformers of threonine and allo-threonine by rotational and vibrational spectroscopies, respectively.",
keywords = "Ab initio calculations, Amino acids, Conformational analysis, Focal-point analysis, Neutral L-allo-threonine, Neutral L-threonine, Structure elucidation",
author = "Tamas Szidarovszky and G. Czak{\'o} and A. Cs{\'a}sz{\'a}r",
year = "2009",
month = "1",
doi = "10.1080/00268970802616350",
language = "English",
volume = "107",
pages = "761--775",
journal = "Molecular Physics",
issn = "0026-8976",
publisher = "Taylor and Francis Ltd.",
number = "8-12",

}

TY - JOUR

T1 - Conformers of gaseous threonine

AU - Szidarovszky, Tamas

AU - Czakó, G.

AU - Császár, A.

PY - 2009/1

Y1 - 2009/1

N2 - Following an extensive search on the potential energy surfaces (PES) of the natural amino acid L-threonine (Thr) and its allotropic form L-allo-threonine (aThr), 56 and 61 conformers of Thr and aThr, respectively, have been located with the help of density functional theory (DFT). Accurate structures, relative energies, rotational as well as quartic and sextic centrifugal distortion constants, dipole moments, 14N nuclear quadrupole coupling constants, anharmonic vibrational frequencies and double-harmonic infrared intensities have been determined from ab initio electronic structure calculations for the five most stable Thr and aThr conformers. The global minimum, Thr-I, has a cyclic triple H-bond motif with strong OH N, C=O HO, and a weaker NH OH H-bond, where the latter two involves the side chain OH, and an energetically unfavourable trans-COOH arrangement. The best relative energies of the conformers, accurate within 1 kJ mol-1, have been determined through the first-principles composite focal-point analysis (FPA) approach. There are four and three conformers of Thr and aThr, respectively, within a relative energy of 5 kJ mol-1. Similarly to other amino acids investigated, lower levels of electronic structure theory, especially the Hartree-Fock level, are unable to determine the correct relative energies of the conformers. The rotational, the quartic and sextic centrifugal distortion, and the 14N nuclear quadrupole coupling constants as well as the anharmonic vibrational fundamentals and double-harmonic infrared intensities, all determined using DFT, should aid identification and characterization of the conformers of threonine and allo-threonine by rotational and vibrational spectroscopies, respectively.

AB - Following an extensive search on the potential energy surfaces (PES) of the natural amino acid L-threonine (Thr) and its allotropic form L-allo-threonine (aThr), 56 and 61 conformers of Thr and aThr, respectively, have been located with the help of density functional theory (DFT). Accurate structures, relative energies, rotational as well as quartic and sextic centrifugal distortion constants, dipole moments, 14N nuclear quadrupole coupling constants, anharmonic vibrational frequencies and double-harmonic infrared intensities have been determined from ab initio electronic structure calculations for the five most stable Thr and aThr conformers. The global minimum, Thr-I, has a cyclic triple H-bond motif with strong OH N, C=O HO, and a weaker NH OH H-bond, where the latter two involves the side chain OH, and an energetically unfavourable trans-COOH arrangement. The best relative energies of the conformers, accurate within 1 kJ mol-1, have been determined through the first-principles composite focal-point analysis (FPA) approach. There are four and three conformers of Thr and aThr, respectively, within a relative energy of 5 kJ mol-1. Similarly to other amino acids investigated, lower levels of electronic structure theory, especially the Hartree-Fock level, are unable to determine the correct relative energies of the conformers. The rotational, the quartic and sextic centrifugal distortion, and the 14N nuclear quadrupole coupling constants as well as the anharmonic vibrational fundamentals and double-harmonic infrared intensities, all determined using DFT, should aid identification and characterization of the conformers of threonine and allo-threonine by rotational and vibrational spectroscopies, respectively.

KW - Ab initio calculations

KW - Amino acids

KW - Conformational analysis

KW - Focal-point analysis

KW - Neutral L-allo-threonine

KW - Neutral L-threonine

KW - Structure elucidation

UR - http://www.scopus.com/inward/record.url?scp=68249141550&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=68249141550&partnerID=8YFLogxK

U2 - 10.1080/00268970802616350

DO - 10.1080/00268970802616350

M3 - Article

AN - SCOPUS:68249141550

VL - 107

SP - 761

EP - 775

JO - Molecular Physics

JF - Molecular Physics

SN - 0026-8976

IS - 8-12

ER -