Determination of some biological activities of protein hydrolysates enzymatically obtained from limpet (patella vulgata)

In this thesis study, it was aimed to extract and characterize total protein from a sea snail species called limpet (Patella vulgata) and to prepare protein hydrolysates. The physicochemical properties and digestibility of limpet protein concentrate, as well as angiotensin-converting enzyme (ACE) inhibition and antioxidant activities of hydrolysates obtained following in vitro gastrointestinal digestion (INFOGEST) were assessed. All digested hydrolysates examined outperformed limpet protein concentrate in terms of activity. A total of 7 and 6 peptides were identified in gastric digestion and gastrointestinal digestion hydrolysates, respectively, using a database search and de novo approach with data obtained by LC-MS/MS after gastrointestinal digestion. Most of the identified peptides were found to possess hydrophobic and aromatic amino acid sequences that may contribute to their antioxidant and ACE inhibitory activities. In this thesis, the production and characterization of different bioactive protein hydrolysates from limpet protein concentrate using commercial food-grade proteases such as Alcalase and Flavourzyme were also carried out. In addition to ACE inhibition and antioxidant activities of protein hydrolysates produced with these enzymes, the inhibition effect against dipeptidyl peptidase IV (DPP-IV) was also investigated. In general, hydrolysates generated with Alcalase from limpet protein concentrate showed higher in vitro activity compared to hydrolysates generated with Flavourzyme. The findings of this study showed that limpet protein concentrate has high nutritional quality with good digestibility for human consumption containing a series of encoded bioactive peptide sequences. The findings indicated that hydrolysates obtained following gastrointestinal digestion could serve as a potential source of antioxidative and ACE inhibitory peptides. Furthermore, these findings indicated that limpet protein hydrolysates produced with Alcalase could be a promising source of bioactive peptides for the development of novel antioxidants as well as ACE and DPP-IV inhibitors associated with Type-2 diabetes and hypertension diseases.