Macroporous resin purification of grass carp fish (Ctenopharyngodon idella) scale peptides with in vitro angiotensin-I converting enzyme (ACE) inhibitory ability

The adsorption dynamics and thermodynamics of grass carp fish scale peptides (FSPs) onto non-polar macroporous resins (MARs), DA201-C, have been investigated. The adsorption of FSPs was affected by time, pH and peptide concentration. The adsorption process followed the Langmuir adsorption isotherm, and was endothermic (ΔH < 43 kJ/mol). The predominant force in adsorption of FSPs onto DA201-C was hydrophobic. Depending on this force, the dynamic adsorption and gradient desorption results showed that DA201-C resins were good at desalting and enriching peptides with higher contents of hydrophobic amino acids, and these peptides had higher ACE inhibitory capabilities in vitro. The lowest concentration at which the eluted fraction possessed half of its original ACE activity (IC50) was 0.13 mg/ml. The results indicated that fish scale peptides produced showed good ACE-inhibitory effect in vitro and fish scales are a good source of peptides with in vitro ACE inhibitory activity.