Separation and Purification of Angiotensin I Converting Enzyme Inhibitory Peptide in Peptic Hydrolyzate of Oyster.

Abstract

Oyster protein was hydrolyzed with eleven kinds of proteases for food industry and the taste of the hydrolyzed extracts were scored by sensory tests. The hydrolyzate treated with denazyme AP was the most preferable extract, and the hydrolyzate (PA-1) was tested for inhibitory activity against angiotensin I converting enzyme (ACE). The IC50-value of PA-1 was 0.55 mg-protein/ml. The PA-1 was applied on a column packed with ODS resin and washed with water in order to remove salts and the water-soluble fraction. The active fraction was eluted with a stepwise gradient of ethanol. The most active fraction (A-3) was eluted with 25% ethanol and showed the IC50-value of 0.085 mg-protein/ml. A peptide that inhibited ACE was isolated from A-3 by use of different modes of chromatography involving SP-Sephadex C-25 and Toyopearl HW-40 followed by three steps of high-performance liquid chromatography. The amino acid sequence and the IC50-value of the isolated peptide was Leu-Phe and 126 muM, respectively