Qian Zhong-Ji, Je Jae-Young, Kim Se-Kwon
Department of Chemistry, Pukyong National University, Busan 608-737, Korea.
J Agric Food Chem. 2007 Oct 17;55(21):8398-403. doi: 10.1021/jf0710635. Epub 2007 Sep 26.
Angiotensin I converting enzyme (ACE) inhibitory peptide was isolated from tuna dark muscle hydrolysate prepared by alcalase, neutrase, pepsin, papain, alpha-chymotrypsin, and trypsin, respectively. Among hydrolysates, the pepsin-derived hydrolysate exhibited the highest ACE I inhibitory activity versus those of other enzyme hydrolysates. The structure of the peptide was identified to be Trp-Pro-Glu-Ala-Ala-Glu-Leu-Met-Met-Glu-Val-Asp-Pro (molecular weight 1581 Da) by time of flight mass spectrometry/mass spectrometry analysis, and the IC 50 value of the peptide was 21.6 microM. The Lineweaver-Burk plots revealed that the peptide acts as a noncompetitive inhibitor, and the inhibitor constant ( K i) was calculated as 26.6 microM using the secondary plots. The peptide had an antihypertensive effect according to the time-course measurement after oral administration to spontaneously hypertensive rats. Maximal reduction was detected 3 h after oral administration at a dose of 10 mg/kg of body weight. These results suggest that the peptide derived from tuna dark muscle would be a beneficial ingredient for functional food or pharmaceuticals against hypertension and its related diseases.
从分别用碱性蛋白酶、中性蛋白酶、胃蛋白酶、木瓜蛋白酶、α-糜蛋白酶和胰蛋白酶制备的金枪鱼黑肉水解物中分离出血管紧张素I转换酶（ACE）抑制肽。在这些水解物中，胃蛋白酶水解物相对于其他酶水解物表现出最高的ACE I抑制活性。通过飞行时间质谱/质谱分析确定该肽的结构为Trp-Pro-Glu-Ala-Ala-Glu-Leu-Met-Met-Glu-Val-Asp-Pro（分子量1581 Da），该肽的IC50值为21.6 μM。Lineweaver-Burk图显示该肽作为非竞争性抑制剂起作用，使用二级图计算抑制剂常数（Ki）为26.6 μM。对自发性高血压大鼠口服给药后的时间进程测量表明该肽具有降压作用。在口服剂量为10 mg/kg体重后3小时检测到最大降压效果。这些结果表明，来自金枪鱼黑肉的肽可能是功能性食品或抗高血压及其相关疾病药物的有益成分。
