Search results for "theoretical conformational analysis"
showing 2 items of 2 documents
Experimental and theoretical NMR and IR studies of the side‐chain orientation effects on the backbone conformation of dehydrophenylalanine residue
2011
Conformation of N‐acetyl‐(E)‐dehydrophenylalanine N′, N′‐dimethylamide (Ac‐(E)‐ΔPhe‐NMe2) in solution, a member of (E)‐α, β‐dehydroamino acids, was studied by NMR and infrared spectroscopy and the results were compared with those obtained for (Z) isomer. To support the spectroscopic interpretation, the ϕ, ψ potential energy surfaces were calculated at the MP2/6‐31 + G(d,p) level of theory in chloroform solution modeled by the self‐consistent reaction field‐polarizable continuum model method. All minima were fully optimized by the MP2 method and their relative stabilities were analyzed in terms of π‐conjugation, internal H‐bonds and dipole interactions between carbonyl groups. The obtained N…
β-turn tendency in N-methylated peptides with dehydrophenylalanine residue: DFT study.
2010
The tendency to adopt β-turn conformation by model dipeptides with α,β-dehydrophenylalanine (ΔPhe) residue in the gas phase and in solution is investigated by theoretical methods. We pay special attention to a dependence of conformational properties on the side-chain configuration of dehydro residue and the influence of N-methylation on β-turn stability. An extensive computational study of the conformational preferences of Z and E isomers of dipeptides Ac-Gly-(E/Z)-ΔPhe-NHMe (1a / 1b) and Ac-Gly-(E/Z)-ΔPhe-NMe(2) (2a/2b) by B3LYP/6-311++G(d,p) and MP2/6-311++G(d,p) methods is reported. It is shown that, in agreement with experimental data, Ac-Gly-(Z)-ΔPhe-NHMe has a great tendency to adopt …