Purification and characterization of β-secretase inhibitory peptide from sea hare (Aplysia kurodai) by enzymatic hydrolysis

Abstract

Abstract Amyloid plaque, also called senile plaque, the product of aggregation of β-amyloid peptides (Aβ), is observed in brains of the patients with Alzheimer’s disease (AD) and is one of the key factors in etiology of the disease. In this study, hydrolysates obtained from the sea hare (Aplysia kurodai) were investigated for β-secretase inhibitory peptide. The sea hare’s muscle protein was hydrolyzed using six enzymes in a batch reactor. Trypsin hydrolysate had highest β-secretase inhibitory activity compared to the other hydrolysates. β-secretase inhibitory peptide was separated using Sephadex G-25 column chromatography and high-performance liquid chromatography on a C18 column. β-secretase inhibitory peptide was identified as eight amino acid residues of Val-Ala-Ala-Leu-Met-Leu-Phe-Asn by N-terminal amino acid sequence analysis. IC50 value of purified β-secretase inhibitory peptide was 74.25 μM, and Lineweaver−Burk plots suggested that the peptide purified from sea hare muscle protein acts as a competitive inhibitor against β-secretase. Results of this study suggest that peptides derived from sea hare muscle may be beneficial as anti-dementia compounds in functional foods or as pharmaceuticals.

Keywords

• β-secretase inhibitory activity
• Sea hare muscle
• Peptide
• Purification
• Alzheimer’s disease