title: Ramachandran Plot for Alanine Dipeptide as Determined from Raman Optical Activity.
abstract: Accessible values of the φ and ψ torsional angles determining peptide main chain conformation are traditionally displayed in the form of Ramachandran plots. The number of experimental methods making it possible to determine such conformational distribution is limited. In the present study, Raman optical activity (ROA) spectra of Ac-Ala-NHMe were measured and fit by theoretical curves. This revealed the most favored conformers and a large part of the potential energy surface (PES) of this model dipeptide. Such experimental PES compares well to quantum chemical computations, whereas molecular dynamics (MD) modeling reproduces it less faithfully. The surface shape is consistent with the temperature dependence of the spectra, as observed experimentally and predicted by MD. Despite errors associated with spectral modeling and the measurement, the results are likely to facilitate future applications of ROA spectroscopy.
authors.affiliation: Institute of Organic Chemistry and Biochemistry, Academy of Sciences , Flemingovo náměstí 2, 16610 Prague, Czech Republic.|Department of Analytical Chemistry, Institute of Chemical Technology , Technická 5, 16628 Prague, Czech Republic.
authors.forename: Václav
authors.initials: V
authors.lastname: Parchaňský
authors.affiliation: Department of Optics, Palacký University Olomouc , 17. listopadu 12, 77146 Olomouc, Czech Republic.
authors.forename: Josef
authors.initials: J
authors.lastname: Kapitán
authors.affiliation: Institute of Organic Chemistry and Biochemistry, Academy of Sciences , Flemingovo náměstí 2, 16610 Prague, Czech Republic.
authors.forename: Jakub
authors.initials: J
authors.lastname: Kaminský
authors.affiliation: Institute of Organic Chemistry and Biochemistry, Academy of Sciences , Flemingovo náměstí 2, 16610 Prague, Czech Republic.
authors.forename: Jaroslav
authors.initials: J
authors.lastname: Šebestík
authors.affiliation: Institute of Organic Chemistry and Biochemistry, Academy of Sciences , Flemingovo náměstí 2, 16610 Prague, Czech Republic.
authors.forename: Petr
authors.initials: P
authors.lastname: Bouř
keywords: Ramachandran plot; Raman optical activity; alanine dipeptide; density functional theory; molecular dynamics; peptide folding