Hydrolysis and purification of ACE inhibitory peptides from the marine microalga Isochrysis galbana

Response surface methodology (RSM) was employed to optimize enzymatic hydrolysis conditions for the production of angiotensin I-converting enzyme (ACE) inhibitory peptides from the marine microalga Isochrysis galbana. A hydrolysis temperature of 55.64 A degrees C, a substrate concentration of 5.46 g (100 mL)(-1), and a trypsin enzyme/substrate ratio (E/S) of 6.27 % were found to be optimal for obtaining the highest ACE inhibitory activity of 47.62 %. The protein hydrolysates were then separated using Sephadex G-25 column chromatography and an AKTA purifier (Inertsil ODS-3 C18, 10 x 250 mm). Using tandem mass spectrometry, the active form of the purified peptide with the most potent ACE inhibitory activity was identified as Tyr-Met-Gly-Leu-Asp-Leu-Lys, with an IC50 of 36.1 mu M. This study improves our understanding of the ACE inhibitory properties of I. galbana protein hydrolysate and may be useful in further identification of ACE inhibitory peptides in other marine algae.