title: Reproducibility and transferability of topological data: experimental charge density study of two modifications of L-alanyl-L-tyrosyl-L-alanine.
abstract: Two crystalline modifications of the tripeptide L-Ala-L-Tyr-L-Ala, which have different solvent molecules in the crystal structure (water and ethanol for modifications 1 and 2), were the subject of experimental charge density studies based on high resolution X-ray data collected at ultra-low temperatures of 9 K (1) and 20 K (2), respectively. The molecular structures and the intermolecular interactions were found to be rather similar in the two crystal lattices, so that this study allowed the reproducibility of the charge density of a given molecule in different (but widely comparable) crystalline environments to be examined. With respect to bond topological and atomic properties, the agreement between the two modifications of the title tripeptide was in the same range as found from the comparison with the previously reported results of tri-L-alanine. It follows that the reproducibility and transferability of quantitative topological data are comparable and that within the accuracy of experimental charge density work the replacement of the central amino acid residue L-Ala by L-Tyr has no significant influence, neither on bond nor on the atomic properties of the oligopeptide main chain. Intermolecular interactions in the form of hydrogen bonds were characterized quantitatively and qualitatively by topological criteria and by mapping the charge density distribution on the Hirshfeld surface.
authors.affiliation: Department of Crystallography and Crystal Chemistry, University of Łódź, Pomorska 149/153, 90 236, Łódź, Poland.
authors.forename: Lilianna
authors.initials: L
authors.lastname: Checińska
authors.forename: Stefan
authors.initials: S
authors.lastname: Mebs
authors.forename: Christian B
authors.initials: CB
authors.lastname: Hübschle
authors.forename: Diana
authors.initials: D
authors.lastname: Förster
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Morgenroth
authors.forename: Peter
authors.initials: P
authors.lastname: Luger
mesh_terms: D000409:Alanine; D018360:Crystallography, X-Ray; D006860:Hydrogen Bonding; D008958:Models, Molecular; D008968:Molecular Conformation; D009842:Oligopeptides / Q000138:chemical synthesis* / Q000737:chemistry*; D055672:Static Electricity; D014443:Tyrosine
chemical_list: D009842:Oligopeptides; D014443:Tyrosine; D000409:Alanine