XPS investigation on the structure of two dipeptides studied as models of self-assembling oligopeptides: comparison between experiments and theory

The adsorption on TiO₂ surface of two dipeptides AE (L-alanine-L-glutamic acid) and AK (L-alanine-L-lysine), that are 'building blocks' of the more complex self-complementary amphiphilic oligopeptides and are therefore a good model in the interpretation of the complex peptide spectra, has been investigated both theoretically and experimentally. The chemical structure and composition of thin films of both dipeptides on TiO₂ were investigated by XPS (X-ray photoelectron spectroscopy). Theoretical ab-initio calculations (ΔSCF) were also performed to simulate the spectra allowing a direct comparison between experiment and theory.