Investigations on isolated peptides by combined IR/UV spectroscopy in a molecular beam – structure, aggregation, solvation and molecular recognition

The well-known correlation between structure and functionality has motivated generations of scientists to intensively investigate the structural behaviour of peptide and protein systems, e.g. their folding, their aggregation reactions or the process of molecular recognition. A variety of environmental effects on peptide structures occur among them the influence of solvent molecules or aggregation partners; a further decisive factor is the amino acid sequence. Thus a bottom-up approach comprises the investigation of isolated peptide systems, increasing in size, as well as a successive introduction of potential aggregation partners. For this purpose mass and isomer selective combined IR/UV investigations in a molecular expansion represent ideal experiments to analyse intrinsic structural properties of peptides and aggregates. Against this background the presented review article illustrates general aspects of peptide structure, spectroscopic methods and experimental set-ups in the first part. This overview is followed by a summary of the current results in this field of research including a more detailed discussion of our work but also selected findings of other groups.