Investigation of structure-activity relationship of ACE inhibitory peptides derived from food proteins

"Milk proteins are a rich source of bioactive peptides with a range of apparent biological activities, eg: antihypertensive, antioxidant and antimicrobial. These peptides could therefore lead to the development of important functional foods however, their commercialization is hindered by restrictive regulations partly due to a lack of substantial evidence to prove the health claims. Research in the production of antihypertensive activity demonstrates that several milk/whey derived peptides possess high in-vitro ACE inhibitory activity however, in some cases poor correlation between the in-vitro ACE inhibitory activity and the in-vivo antihypertensive activity has been observed. This can be partly due to digestion which renders less active peptide sequences and/or due to their low bioavailability. Also antihypertensive activity may be exerted by mechanisms other than ACE inhibition.In our group we have focused on the production of Angiotensin Converting Enzyme (ACE) inhibitory peptides by either enzymatic1-4 or fermentation hydrolysis. We have identified some novel peptide sequences with high ACE inhibitory activity by a combination of chemical characterization (LC/MS; MS/MS) and QSAR data (Welderufael et al 2012). In addition, in collaboration with bioinformatics experts in the School of Biological Sciences we have started developing molecular docking based methodology to predict interactions between particular peptide sequences and the ACE. This will enable us to assess the ACE inhibition potency of these peptide sequences without the need to go through cumbersome purification processes and could help to assess their antihypertensive activity in-vivo. Therefore the research developed here will constitute a fundamental study that will facilitate the investigation of the in-vivo activity of the most promising candidates to prove their efficacy in-vivo.The aim of the present proposal is to further elucidate the structure-activity relationship of peptide sequences present in whey/milk protein hydrolysates with high ACE inhibitory activity.
The specific objectives are:
• Production of a hydrolysate from whey following the enzymatic integrative process developed in the group
• In-vitro gastrointestinal digestion
• Determine ACE inhibitory activity in-vitro
• Determine peptide sequences by mass spectrometry techniques
• Use QSAR data and BIOPEP software to assess ACE inhibitory activity of major peptide sequences
• Use bioinformatic techniques to predict strength of ACE inhibition of most promising candidates and identify potential antihypertensive peptides
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