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目的研究蛋清蛋白肽体外血管紧张素转化酶(ACE)抑制活性以及耐胃肠道消化稳定性。方法采用超滤分离蛋清蛋白酶解产物;利用高效液相色谱法测定蛋白酶水解物及其超滤各组分的体外ACE抑制活性。氨基酸自动分析仪测定ACE抑制活性较高组分(EWPH-Ⅲ)的氨基酸组成。体外模拟胃肠道消化试验测定EWPH-Ⅲ的消化稳定性。RP-HPLC法分析消化产物的组成变化。结果蛋清蛋白水解物的ACE抑制活性随着分子量的降低而增强(P<0.05),分子量小于3ku组分(EWPH-Ⅲ)的ACE抑制效果最好,其IC50值为0.049 mg/ml。EWPH-Ⅲ中疏水性氨基酸和必需氨基酸总量分别为49.51%和50.26%。经过胃肠道消化作用后,EWPH-Ⅲ的ACE抑制活性有所降低,消化产物的RP-HPLC分析结果显示EWPH-Ⅲ中多肽组分发生了明显的变化,胰酶消化产物中疏水性较强的多肽组分含量有所减少。结论蛋清蛋白肽具有较强的ACE抑制活性并且具有很高的营养价值,其ACE抑制活性随着阶段性的胃肠道消化而发生改变。
Objective To study the inhibitory activity of egg white protein (ACE) in vitro on angiotensin converting enzyme (ACE) and gastrointestinal tract digestion stability. Methods The protein hydrolyzate of egg white was separated by ultrafiltration. The inhibitory activity of ACE in vitro was determined by high performance liquid chromatography (HPLC). Amino acid analyzer was used to determine the amino acid composition of the ACE inhibitory activity component (EWPH-III). Digestive stability of EWPH-Ⅲ was determined by in vitro simulated gastrointestinal digestion test. RP-HPLC analysis of digestive product composition changes. Results The ACE inhibitory activity of egg white hydrolyzate was enhanced with the decrease of molecular weight (P <0.05). The ACE inhibitory activity of EWPH-Ⅲ with the molecular weight of less than 3ku was the best, with IC50 of 0.049 mg / ml. The total amounts of hydrophobic and essential amino acids in EWPH-Ⅲ were 49.51% and 50.26%, respectively. The ACE inhibitory activity of EWPH-Ⅲ decreased after digestion in the gastrointestinal tract. The results of RP-HPLC analysis of digestion products showed that the polypeptide components of EWPH-Ⅲ changed significantly, and the hydrophobicity of tryptic digest was stronger The content of polypeptide components decreased. Conclusion Egg albumin peptide has strong ACE inhibitory activity and high nutritional value, and its ACE inhibitory activity changes with the gradual gastrointestinal digestion.