Inhibitory Activity of Angiotensin 1-Converting Enzyme of Phosphopeptides Obtained from Proteolytic Hydrolyzates of Oyster, Crassostrea gigas

Abstract

In the previous papers^(1.2), we investigated the effects of ACE inhibitory activities of phosphopeptides of P-1 and C-2 which were obtained from edible oyster by proteolytic hydrolyzation. In this investigation, the ACE inhibitory phosphopeptides of T-1 was further purified by ultrafiltration and Sephadex G-15 column chromatography. ACE inhibitory activity was fractionated into three major phosphopeptides fractions of T-1-1,T-1-2 and T-1-3 in the pepsin hydrolyzates of the T-1 by gel filtration rechromatography on Sephadex G-15. The inhibition of ACE of the three kinds of phosphopeptides fractions (T-1-1,T-1-2 and T-1-3) was analyzed in vitro. The IC_<50> values of T-1-1,T-1-2 and T-1-3 of phosphopeptides for ACE were 0.159,0.095 and 0.140 mg protein/ml, respectively. The T-1-2 fraction had the most potent inyhibitory activity and showed 0.095 mg protein/ml inhibition against ACE at IC_<50> value. It has been demonstrated that the T-1-1,T-1-2 and T-1-3 contained about 33.3%, 3.01% and 27.12% as phosphonate-phosphorus of total phosphorus. The amino acid compositions of the phosphopeptides fractions (T-1-1,T-1-2 and T-1-3) were characterized by relatively high percentage for Tyr, Ser, Arg, Ala, Asp and Phe. When the ACE inhibitory phosphopeptides were analyzed by thin layer chromatography, some ninhydrine-positive spots were observed. These results suggest that the phosphopeptides are a mixture of several phosphopeptides.