Purification and characterisation of angiotensin I converting enzyme (ACE) inhibitory peptides derived from enzymatic hydrolysate of ovotransferrin

Three novel peptides, IQW, IRW and LKP, were predicted in our previous study in the thermolysin–pepsin ovotransferrin hydrolysate. The aims of the present study were to purify the peptides, and determine if the predicted peptides purified from the hydrolysate would have the same activity as the synthetic ones. We also determined the stability of the peptides under simulated gastrointestinal condition. IQW, IRW and LKP were then successfully purified from crude ovotransferrin hydrolysate through multi-step chromatographic purification comprising of cation exchange chromatography followed by three-step reverse-phase high performance liquid chromatography (RP-HPLC), and their sequences were analysed by UPLC-MS/MS. Our results showed that their activities were comparable to the synthetic ones. Simulated gastrointestinal incubation showed that IRW was degraded into a dipeptide of IR and a free amino acid of W by pancreatin, LKP was degraded into a dipeptide of KP and a free amino acid of L by mucosal peptidase, while IQW was stable against the digestive enzymes.