Quantitative structure–activity relationship based screening of bioactive peptides identified in ripened cheese

Abstract

The peptide profile of a ripened cheese (Basque Idiazabal D.O.) was analysed using an orthogonal HPLC separation, strong cation exchange chromatography followed by reverse-phase liquid chromatography, in combination with matrix assisted laser desorption/ionization time-of-flight mass spectrometry. The spectra obtained were searched against several in house databases for peptide fragment fingerprint identification. 231 Peptides from milk proteins and from microbial enzymes fragments were identified. The potential angiotensin-converting enzyme- (ACE-) inhibitory activity of the identified peptides was predicted with a quantitative structure–activity relationship model developed previously for peptides with a length larger than 5 residues. Ten peptides were synthesised and tested for their in vitro ACE-inhibitory activity, among them six novel peptides presented a high activity in vitro with IC50 values of between 4 and 32 μm. The proposed methodology can be used for screening for bioactive peptides in complex matrices, such as ripened cheese.