富硒螺旋藻蛋白水解多肽的制备及其对ACE活性的抑制作用

从富硒螺旋藻(SeSP)中提取含硒总蛋白(SeSP-TP),建立蛋白酶水解制备含硒多肽(SeSP-PP)的最佳条件,体外检测SeSP-PP对血管紧张素转化酶(ACE)活性的抑制作用,采用ICP法快速测定藻粉及总蛋白中的硒含量。结果发现,5种常见蛋白酶对SeSP-TP的水解度趋势为:胃蛋白酶-胰蛋白酶-胰凝乳蛋白酶联合酶>碱性蛋白酶>木瓜蛋白酶>胰凝乳蛋白酶>胰蛋白酶>胃蛋白酶。利用胃蛋白酶-胰蛋白酶-胰凝乳蛋白酶联合酶水解,可显著提高蛋白水解度,达到87.94%,且联合水解的多肽对ACE抑制效率最高(89.47%)。碱性蛋白酶水解得到的多肽对ACE的抑制率也较高。当荧光检测出的含硒多肽高于50μg/mL时,对NO的合成有明显的促进效应,而含硒蛋白效果不明显。水溶性和非水溶性组分中测定的硒含量之和占总硒的95.47%,可能在提取制备SeSP-TP过程中,部分含硒蛋白质和含硒小分子会在沉淀、复溶和透析等步骤中丢失。

Preparation of Polypeptides by Hydrolysis of Selenium-enriched Spirulina Protein and their Inhibitory Activity for Angiotensin-converting Enzyme

The water soluble total protein (TP) of selenium-enriched Spirulina platensis (SeSP), named as SeSP-TP, was extracted by phosphate buffer and then hydrolyzed by 5 different proteases to produce SeSP peptides (SeSP-Ps). The angiotensin-converting enzyme (ACE) inhibitory activity of SeSP-Ps was measured in vitro and ICP method was used to rapidly determinate of selenium in algae powder and total protein content. The results showed that treatments with different proteases caused different degree of hydrolysis (DH) of SeSP-TP, and the combination digestion by pepsin, trypsin and chimotrypsin led to the highest DH value. The SeSP-Ps obtained via hydrolysis by the combination digestion of pepsin, trypsin and chimotrypsin showed the highest ACE-inhibitory activity (89.47%). The ACE inhibition efficiency of polypeptides prepared by alkaline protease is higher. Fluorescence detection showed that, when the content of selenium peptides was above 50 mu g/mL, the synthesis of NO was obviously promoted. However, selenium protein showed little effect on the reaction.Selenium contents in both water-soluble and water-insoluble components accounted for 95.47% of total selenium, probably due to that in extraction and preparation of SeSP-TP, some selenium protein and small molecules containing selenium missed in precipitation, dissolution and dialysis steps.