First-principle computational study on the full conformational space of L-threonine diamide, the energetic stability of Cis and trans isomers

Michelle A. Sahai, Szilard N. Fejer, Bela Viskolcz, Emil F. Pai, Imre G. Csizmadia

Research output: Contribution to journalArticle

13 Citations (Scopus)

Abstract

First-principle computations were carried out on the conformational space of trans and cis peptide bond isomers of HCO-Thr-NH2. Using the concept of multidimensional conformational analysis (MDCA), geometry optimizations were performed at the B3LYP/6-31G(d) level of theory, and single-point energies as well as thermodynamic functions were calculated at the G3MP2B3 level of theory for the corresponding optimized structures. Two backbone Ramachandran-type potential energy surfaces (PESs) were computed, one each for the cis and trans isomers, keeping the side chain at the fully extended orientation (χ1 = χ2 = anti). Similarly, two side chain PESs for the cis and trans isomers were generated for the (φ = Ψ = anti) orientation corresponding to approximately the βL backbone conformation. Besides correlating the relative Gibbs free energy of the various stable conformations with the number of stabilizing hydrogen bonds, the process of trans → cis isomerization is discussed in terms of intrinsic stabilities as measured by the computed thermodynamic functions.

Original languageEnglish
Pages (from-to)11527-11536
Number of pages10
JournalJournal of Physical Chemistry A
Volume110
Issue number40
DOIs
Publication statusPublished - Oct 12 2006

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry

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