Computational study of conformational preferences of thioamide-containing azaglycine peptides.
The effect of thioamide substitution on the conformational stability of an azaglycine-containing peptide, For-AzaGly-NH2 (1), was investigated for the sake of finding possible applications by using ab initio and DFT methods. As model compounds, For-[psiCSNH]-AzaGly-NH2 (2), For-AzaGly-[psiCSNH]-NH2 (3), and For-[psiCSNH]-AzaGly-[psiCSNH]-NH2 (4) were used. Two-dimensional phi-psi potential energy surfaces (PESs) for 2-4 were calculated at the B3LYP/6-31G*//HF/6-31G* level in gas (epsilon = 1.0) and in water (epsilon = 78.4) by applying the isodensity polarizable continuum model (IPCM) method. On the basis of these PESs, the minimum energy conformations for 2-4 were characterized at the B3LYP level with 6-31G*, 6-311G**, and 6-31+G** basis sets. The remarkable structural effect of thioamide substitution for 2-4 is that beta-strand structure is observed as a global or local minimum. The minima of 2-4 are also compared with those for glycine and thioamide-containing glycine peptides. Our theoretical results demonstrate that compounds 2-4 would be used to design controllable secondary structures.
Lee
Ho-Jin
HJ
Department of Chemistry, Korea University, 1 Anam dong, Seoul, 136-701, Korea.
Kim
Jong Hyun
JH
Jung
Hee Jung
HJ
Kim
Kun-Young
KY
Kim
Eun-Jung
EJ
Choi
Young-Sang
YS
Yoon
Chang-Ju
CJ
D005998:Glycine / Q000031:analogs & derivatives* / Q000737:chemistry*; D006860:Hydrogen Bonding; D008958:Models, Molecular; D008968:Molecular Conformation; D010455:Peptides / Q000737:chemistry*; D011487:Protein Conformation; D013816:Thermodynamics; D013854:Thioamides / Q000737:chemistry*
D010455:Peptides; D013854:Thioamides; D005998:Glycine