特异性蛋白酶酶解虾副产物制备ACE抑制肽

ACE抑制肽构效关系(QSAR)的研究认为小肽C末端氨基酸的疏水性和其ACE抑制活性之间呈正相关关系。针对性地选择胰凝乳蛋白酶和脯氨酸蛋白酶两步酶解虾副产物制备ACE抑制肽。在一定温度、pH和加酶量条件下,以蛋白质的水解度和ACE抑制率为指标,确定胰凝乳蛋白酶、脯氨酸蛋白酶的最佳酶解时间均为4h。两步酶解产物ACE抑制的IC50值为1.645mg protein/mL。经透析后,得到0~500u(组分1)和500~1000u(组分2)两个组分,组分1和组分2的IC50值分别降为0.333mg peptide/mL和1.320mg peptide/mL。质谱分析结果表明组分1中含有10个肽,分别由5~14个氨基酸组成;组分2中含有15个肽,分别由7~14个氨基酸组成。25个已知序列多肽中有22个多肽的羧基端是脯氨酸或芳香族氨基酸,与预期相符。 

Preparation of angiotensin I-converting enzyme inhibitory peptides derived from shrimp byproduct by specific enzyme hydrolysis method

Based on the quantitative structure- activity relationship and predictive models of angiotensin I-converting enzyme (ACE) inhibitory peptide, hydrophobic amino acid residues at C-terminal are positively correlated with ACE inhibitory activity. In order to get more proline and hydrophobic amino acid residues at C terminal, α-chymotrypsin and proline protease were chosen to hydrolyse the shrimp byproducts to produce ACE inhibitory peptides. The hydrolysis times were optimized according to the hydrolysis degree (HD) for α-chymotrypsin, and both HD and ACE-inhibitory activity for proline protease, the results showed that the optimal hydrolysis time for both enzyme were 4 hours. The half maximal inhibitory concentration (IC50) for ACE inhibition of hydrolysate was 1.645mg protein/mL. The hydrolysate was separated into fraction 1 (0⁵00u) and fraction 2 (500¹000u) by molecular weight cut-off (MWCO) membrane. The IC50value of fraction 1 and fraction 2 were 0.333mg peptide/mL and 1.320mg peptide/mL, respectively. The peptide mixtures were analyzed by time-of-flight mass spectrometry. Ten peptides, which were consisted of peptides with 5 to 14 amino acid residues, were identified in fraction 1. Fifteen peptides, which were consisted of peptides with 7 to 14 amino acid residues were identified in fraction 2. The C-terminal amino acids of 22 out of the 25 peptides were proline or aromatic amino acid, which was corresponding to QSAR results.