Food peptidomics: large scale analysis of small bioactive peptides--a pilot study.

Unlabelled: Food peptidomics deals in part with the identification and quantification of nutritionally relevant peptides which are called bioactive peptides. This category of peptides comprises large, medium to small peptides. However, small peptides (2-6 amino acids) represent by far the largest category. Such molecules sit at the interface of both the world of proteomics and small molecule. The purpose of this study was to evaluate the feasibility of developing an LC-MSMS based method to measure such small peptides at a large scale that is representative of the hundreds of known small bioactive peptides. In order to do that we selected a very complex and homogeneous peptide set in terms of chemical and physical properties. This peptide set comprised only di, tri- and tetrapeptides made out of the three branched chain amino acids (valine, leucine and isoleucine). Results showed that at least 60% of these 117 peptides can be uniquely identified although many are isobaric and co-eluting. Moreover, identical results were obtained when spiked into a complex matrix, i.e. hydrolyzed whey protein. In conclusion, these results support the feasibility of a large scale approach and open the door to further development for all potential small bioactive peptides known so far.

Biological Significance: Bioactive peptides are a key category of molecules for functional food application. Most known bioactive peptides are small (less than 5 amino acids) and hence represent a challenge in terms of analysis when using current proteomics techniques. Therefore development of the food peptidomics field through high throughput large scale assays for these molecules is mandatory in the future to better conduct research in this field.