Separation and Purification of Angiotensin I Converting Enzyme Inhibitory Peptides from Heated SardineMeat by Treatment with Alkaline Protease

Abstract

Angiotensin I converting enzyme (ACE) inhibitory peptides were prepared from alkaline protease hydrolyzate of heated sardine muscle by applying on a column packed with AMBERLITE XAD-2 resin. The fractions eluted with water and stepwise gradient of ethanol were tested for inhibitory activity against ACE. The most active fraction (AF-1) was obtained by eluting with water and showed the 50% inhibition against ACE at 0.148mg protein/ml. Sensory evaluation revealed that the water soluble fraction (AF-1) had no bitter taste, while fish flavor was perceived as well as that of treatment with ODS resin. Two peptides were isolated from AF-1 by four steps of high-performance liquid chromatography. The amino acid sequences of two peptides identified by Edman degradation were Thr-Tyr and Gly-Trp, and their IC50 values for ACE were 288μM and 86μM, respectively. The yield of two peptides per 20g of sardine muscle were 40.0μg and 74.5μg, respectively, and these were found to be hydrophilic and high polar peptides.