Berlin 2014 – wissenschaftliches Programm

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MO: Fachverband Molekülphysik

MO 24: Biomolecules 2

MO 24.6: Vortrag

Freitag, 21. März 2014, 15:15–15:30, BEBEL SR144

Binding motifs of a microsolvated neurotransmitter: IR spectroscopy of Ar-tagged protonated phenylethylamine and its water clusters — •Aude Bouchet, Markus Schütz, and Otto Dopfer — Institut für Optik und Atomare Physik, Technische Universität Berlin, Germany

The characterization of the three-dimensional structure of biologically relevant molecules, the role played by inter- and intramolecular interactions, especially with water which is the ubiquitous solvent in biological media, and their ability to form charged groups, are key issues to be addressed to deepen the understanding of recognition phenomena at the molecular level in biological environments. Biomolecules are generally not neutral in physiological medium, but protonated or zwitterionic. The conformation of these charged molecules and their solvation shell is thereby modified compared to neutral species. Here, vibrational spectroscopy, associated with quantum chemical calculations, has been applied on a protonated neurotransmitter, phenylethylamine (H⁺PEA), and its water clusters isolated in the gas phase. The results obtained on the Ar-tagged H⁺PEA show that a strong intramolecular NH⋯π interaction induces conformational locking of the monomer into a folded structure. Monohydrated H⁺PEA reveals that a very stable inclusion structure is experimentally generated, in which the water molecule is inserted between the positively charged amino group and the phenyl moiety of H⁺PEA. This ligand acts both as an hydrogen bond acceptor (NH⋯O) and hydrogen bond donor (OH⋯π). A second isomer, for which the water is H bonded to a ”surface” NH group is also found.