An angiotensin-converting enzyme inhibitory (ACEI) peptide with a median inhibitory concentration (IC50) of 1.26 mg/mL was purified from whey proteins resulting from a fermentation using Lactobacillus plantarum QS670. The peptide was subsequently derived from an αS1-casein, κ-casein, β-lactoglobulin, or serum albumin fraction. Analysis via liquid chromatography tandem mass spectrometry indicated that it had an amino acid sequence of Gly-Ala (GA). The GA dipeptide was also synthesized using an Fmoc solid-phase method. The GA dipeptide exhibited an IC50 of 1.22 mg/mL and was shown to be stable across both temperature (20 to 60°C) and pH (2 to 12). Digestive enzymes including pepsin, trypsin, and chymotrypsin had negligible effects on activity. The whey exerted hypotensive effects when fed to spontaneously hypertensive rats (SHR), which exhibited a blood pressure drop of 2.33 kPa. A 4-wk gavage treatment resulted in greater decreases of 7.46 kPa. Results of this study indicate that milk fermented using Lb. plantarum QS306 has potential to be used as a functional food to help prevent or reduce hypertension-associated diseases.

中文翻译：

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从植物乳杆菌QS670发酵乳中分离的乳清蛋白中分离的血管紧张素转换酶抑制肽的纯化和鉴定。

从植物乳杆菌QS670发酵产生的乳清蛋白中纯化出具有1.26 mg / mL中位抑制浓度（IC50）的血管紧张素转化酶抑制（ACEI）肽。该肽随后衍生自αS1-酪蛋白，κ-酪蛋白，β-乳球蛋白或血清白蛋白级分。通过液相色谱串联质谱分析表明其具有Gly-Ala（GA）的氨基酸序列。还使用Fmoc固相方法合成了GA二肽。GA二肽的IC50为1.22 mg / mL，在温度（20至60°C）和pH（2至12）均显示稳定。消化酶包括胃蛋白酶，胰蛋白酶和胰凝乳蛋白酶对活性的影响可以忽略不计。当喂自发性高血压大鼠（SHR）时，乳清具有降压作用，血压下降了2.33 kPa。4周的管饲法处理导致7.46 kPa的更大降低。这项研究的结果表明，使用Lb发酵牛奶。车前草QS306有潜力用作功能性食品，以帮助预防或减少高血压相关疾病。