Isolation of angiotensin I converting enzyme inhibitory peptides from a fish by-products hydrolysate Tensideal®

Introduction Many ACE inhibitory peptides have been isolated from various protein hydrolysates such as casein, soybean or fish protein. The purpose of this work is to isolate ACE inhibitory peptides derived from an enzymatic hydrolysate of fish by-products named Tensideal®, which is actually produced industrially by IDMER. The measurement of ACE inhibitory activity was performed using a HPLC method consisting on measuring the levels of the substrate (FAPGG (N-(3-[2furylacryloyl)-Phe-Gly-Gly)) or the product formed (FAP) with and without inhibitor. By this method, the hydrolysate Tensideal® showed an IC50 of 65μg of peptides while the reference Captopril® showed an IC50 of 0.3ng. To isolate ACE inhibitory peptides from the hydrolysate, different chromatographic methods were successively applied to select step by step the most active fraction. Gel filtration has demonstrated that major peptides have molecular weight less than 1000 Da and some tests realised by C18 HPLC have showed that active peptides were very polar molecules. After gel filtration, SPE and LC-MS, we succeeded in identifying an active fraction with an interesting mass profile. The interpretation of the mass spectrum is actually in progress.