College of Food Science, Jiangnan University, Wuxi 214122, People's Republic of China.
Food Chem. 2013 Nov 1;141(1):153-9. doi: 10.1016/j.foodchem.2013.02.087. Epub 2013 Mar 7.
In this study, rapeseed protein isolate (RPI) was digested with various proteases to produce rapeseed protein hydrolysates (RPHs), which were then separated into different peptide fractions (<1, 1-3, 3-5, and 5-10kDa) by membrane ultrafiltration. Membrane fractionation showed that peptides with sizes <3 kDa had significantly (p<0.05) reduced surface hydrophobicity when compared to the RPHs and peptide fractions with sizes >3 kDa. In contrast, the <3 kDa peptides showed significantly (p<0.05) higher oxygen radical scavenging ability when compared to the >3 kDa peptides and RPHs. In vitro inhibition of angiotensin I-converting enzyme (ACE) was significantly (p<0.05) higher for the Thermolysin, Proteinase K and Alcalase RPHs when compared to the pepsin+pancreatin (PP) and Flavourzyme RPHs. The Alcalase RPH had significantly (p<0.05) higher renin inhibition among the RPHs, while with the exception of Thermolysin, the 5-10 kDa peptide fraction had the least renin-inhibitory ability when compared to the <5 kDa peptide fractions. Oral administration (100mg/kg body weight) of the RPHs and RPI to spontaneously hypertensive rats (SHR) showed the Alcalase RPH to be the most effective in blood pressure (BP) reduction (∼24 mm Hg) while Proteinase K RPH was the least effective (∼5 mm Hg) after 8h. However, the PP RPH had the most prolonged effect with BP reduction of ∼20 mm Hg after 24h of oral administration. We conclude that the strong BP-lowering ability of Alcalase and PP RPHs could be due to high resistance of the peptides to structural degradation coupled with high absorption rate within the gastrointestinal tract.
在这项研究中，采用不同的蛋白酶将菜籽蛋白分离物（RPI）进行酶解，生成菜籽蛋白水解物（RPH），然后通过膜超滤将其分离成不同的肽段（<1、1-3、3-5 和 5-10 kDa）。膜分级表明，与 RPH 和>3 kDa 的肽段相比，<3 kDa 的肽段的表面疏水性显著降低（p<0.05）。相比之下，<3 kDa 的肽段的氧自由基清除能力显著高于>3 kDa 的肽段和 RPH（p<0.05）。与胃蛋白酶+胰蛋白酶（PP）和风味蛋白酶 RPH 相比，胰蛋白酶、蛋白酶 K 和碱性蛋白酶 RPH 对血管紧张素 I 转换酶（ACE）的体外抑制作用显著更高（p<0.05）。在 RPH 中，Alcalase RPH 对肾素的抑制作用显著更高（p<0.05），而除了胰蛋白酶外，与<5 kDa 的肽段相比，5-10 kDa 的肽段具有最低的肾素抑制能力。RPH 和 RPI 经口给予自发性高血压大鼠（SHR）（100mg/kg 体重）后，Alcalase RPH 降低血压的效果最为显著（约 24mmHg），而蛋白酶 K RPH 的效果最不显著（约 5mmHg），8h 后。然而，PP RPH 的降压作用持续时间最长，口服 24h 后，BP 降低约 20mmHg。我们得出结论，Alcalase 和 PP RPH 的强降压能力可能是由于肽的结构降解具有高抗性，与胃肠道内的高吸收率相结合。
