STSM by Alexander Kaiser, University of Innsbruck (AT) with Yoni Toker, Bar-Ilan University (IL)
On January 18, 2017 (24 days)

Homochiral and heterochiral clusters of amino acids: What makes the difference?

Amino acids build peptides and proteins which are major building blocks of cells. Most of them exist in two structural motifs namely L-chirality and D-chirality. In this collaboration which was initiated within the COST XLIC network, we studied clusters of a single or two different amino acids with a focus on the influence of chirality on the clustering behavior. Intrigued by the fact that homochiral samples can form particularly stable clusters, we studied their collision activated fragmentation and also started with combinations that have not yet been reported and that will give us more hints on the structure of theses hydrogen-bonded clusters.

A homochiral mass-selected Serine octamer cluster has been activated by collisions with argon. With increasing collision energy, the clusters sequentially lose single Serine molecules. The mass distributions do not point to a particularly stable substructure such as a dimer or trimer unit. With further increase of the collision energy, the Serine monomer starts to fragment by loss of water or formic acid. Furthermore, spectra for mixed Serine-Valine and mixed Proline-AA clusters have been obtained for several amino acids (AA) and different chirality.

We plan to write a publication on our results and to extend our studies within a new collaborative research project.

Figure: Fragmentation of the mass selected protonated serine octamer

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