Formation of Neutral Peptide Aggregates Studied by Mass Selective IR Action Spectroscopy

The spontaneous aggregation of proteins and peptides is widely studied due to its relation to neurodegenerative diseases. To understand the underlying principles of peptide aggregation, elucidation of structure and structural changes upon their formation is key. This level of detail can be obtained by studying the peptide self-assembly in the gas phase. Structural characterization of aggregates is mainly done on charged species, as adding charges is an intrinsic part of the technique to bring molecules into the gas phase. Studying neutral peptide aggregates will complement the existing picture. These studies are restricted to dimers due to experimental limitations. Here, we present advances in laser desorption molecular beam spectroscopy to form neutral peptide aggregates in the gas phase consisting of up to fourteen monomeric peptides. The combination with IR-UV spectroscopy allowed us to select each aggregate by size and subsequently characterize its structure.