Purification and sequencing of some angiotensin I-converting enzyme inhibitory peptides from egg white hydrolysate

• Main Authors: Chi-ya Haung, 黃琪雅
• Other Authors: Tsun-Chung Tsai
• Format: Others
• Language: zh-TW
• Published: 2009
• Online Access: http://ndltd.ncl.edu.tw/handle/49805433112471698116

碩士 === 東海大學 === 食品科學系 === 98 === Hypertension is one of most common chronic diseases found in modern society. It is well known that ACE(Angiotensin I-converting enzyme) is one important regulatory factor leading to the hypertension and ACE inhibitor is common medicine used to reduce the high pressure. It has been reported that crude egg albumine could be easily hydrolyzed by thermolysin into small peptides and 0.2g hydrolysate/ kg body weight has been found effectively to reduce blood pressure in SHR experiment. In this study, IC50 for ACE of hydrolysate from egg albumin by thermolysin digestion for 4 hours was found to be 14.15 μg/mL. Ultafiltration was applied to fractionation the hydrolysate. ACE inhibitory activity was increased when average MW of fraction was decreased. IC50 of hydolysate fraction with low MW(molecule weight) (＜ 1KDa) was found to be 9.37 μg/mL. Semi-preparative RP-18 column was used in HPLC(High Performance Liquid Chromatography) to separate the low MW fraction into five portions according elution time. The portion with most effective ACE inhibitory activity was further purified repeatedly with analytic column. Amino acid sequence and IC50 of seven peptides were identified and measured: Trp-Ser (IC50=63.85 μM), Leu-Glu-Pro (IC50=39.79 μM, Ala-Phe (IC50=121.17 μM), Val-Phe-Lys-Glu (IC50=489.21 μM), Leu-Tyr (IC50=107.77 μM), Leu-Trp-Glu-Lys (IC50=52.72 μM), and Phe-Gly (IC50=407.76 μM).