虾头在一定的条件下发生自溶作用,其所含蛋白质以肽和氨基酸等形式释放出来,有些肽产物具有ACE抑制活性.实验采用8000、5000和3000 u的超滤膜分级分离虾头自溶产物,活性检测结果表明,ACE抑制肽主要分布在3000 u超滤组分中；3000 u超滤组分进一步经Sephadex G-25葡聚糖凝胶层析、SP Sephadex C-25离子交换层析及Sephadex G-15葡聚糖凝胶层析纯化,ACE抑制活性提高将近8倍(IC50 =0.19 mg/mL)；Sephadex G-15葡聚糖凝胶层析收集的高活性成分再经两次RP-HPLC纯化,分离纯化得到两条ACE抑制肽,质谱分析推测其氨基酸序列为Tyr-Pro和Leu-Pro/Ile-Pro,分子量分别为279和229 u.%Shrimp head is susceptible to autolysis under certain conditions,the protein in it is degraded into soluble protein,peptides and amino acids,and some peptides are active peptides which can inhibit the ACE enzyme activity. At present,many ACE inhibitory peptides derived from food protein have been developed. In the present study, two ACE inhibitory peptides ( Tyr-Pro and Leu-Pro/He-Pro) were highly purified from the shrimp head ( Litopenaeus vannamei) autolysate by extra fine membrane and a series of column chromatographies. In the first autolysis solution of shrimp head was consecutively extracted through extra fine membrane with molecular weight cut-offs (MWCO) at 8,5,3 ku, respectively. The active results shown that filtrate through MWCO at 3 000 u had the highest ACE inhibitory activity. The crude filtrate through MWCO at 3 ku was purified by Sephadex G-25 gel chromatography, SP Sephadex C-25 anion-exchange chromatography as well as Sephadex G-15 gel chromatography,respectively. After that,the ACE inhibitory activity of purified filtrate almost increased by 8 times(IC50 =0. 19 mg/mL)that of crude filtrate. The high active collected fraction from Sephadex G-15 gel chromatography was carried out by RP-HPLC ( High Performance Liquid Chromatography) twice for the further purification and two kinds of dipeptide were obtained, and the identification of dipeptide by mass spectra showed that they were Tyr-Pro and Leu-Pro/Ile-Pro,and the molecular weight was 279 u and 229 u,respectively.
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