title: Structural investigations on a linear isolated depsipeptide: the importance of dispersion interactions.
abstract: In this paper we present the first investigations on an isolated linear depsipetide CyCO-Gly-Lac-NH-PhOMe (cyclohexylcarbonyl-glycine-lactate-2-anisidine abbreviated as MOC) in a molecular beam experiment. Depsipeptides are a special subclass of peptides which contain at least one ester bond replacing a peptide bond. This leads to a different folding behavior and a different biological activity compared to a "normal" peptide. In order to analyze the folding of an isolated depsipeptide on a molecular level a variety of combined IR/UV methods including IR/IR/UV experiments are applied to MOC. Three different isomers are identified in combination with DFT calculations using the hybrid functional B3LYP-D3 with a TZVP basis set. The most stable structure shows a tweezer-like arrangement between the aromatic chromophore and the aliphatic cyclohexyl ring. A characteristic feature of this structure is that it is stabilized by dispersion interactions resulting from CH/π interactions. If dispersion is not taken into account this structural arrangement is no longer a minimum on the potential energy surface indicating the importance of dispersion interactions.
authors.affiliation: TU Kaiserslautern, Fachbereich Chemie & Research Center Optimas, Erwin-Schroedinger-Straße 52, D-67663 Kaiserslautern, Germany. gerhards@chemie.uni-kl.de.
authors.forename: A
authors.initials: A
authors.lastname: Stamm
authors.affiliation: TU Kaiserslautern, Fachbereich Chemie & Research Center Optimas, Erwin-Schroedinger-Straße 52, D-67663 Kaiserslautern, Germany. gerhards@chemie.uni-kl.de.
authors.forename: D
authors.initials: D
authors.lastname: Bernhard
authors.affiliation: TU Kaiserslautern, Fachbereich Chemie & Research Center Optimas, Erwin-Schroedinger-Straße 52, D-67663 Kaiserslautern, Germany. gerhards@chemie.uni-kl.de.
authors.forename: M
authors.initials: M
authors.lastname: Gerhards