ABSTRACT Non‐covalent sulfur–aromatic () interactions play a crucial role in stabilizing the structure of proteins and have been associated with neurodegenerative diseases. We investigated the influence of the interaction on the electronic structure and fragmentation behavior of sequence‐isomer model peptides by means of ultraviolet photodissociation (UVPD) and near‐edge x‐ray absorption mass spectrometry (NEXAMS). The studies revealed distinct fragmentation behavior for one of the model peptide