Abstract: Bioactive peptides were prepared from sheep casein by neutral protease hydrolysis. The effect of hydrolysis time on the degree of hydrolysis and angiotensin converting enzyme (ACE) inhibitory activity of hydrolsates was investigated. The peptides were analyzed and identified by liquid chromatography-mass spectrometry (LC-MS) to select the ones with potential ACE inhibitory activity. The results showed that the highest degree of hydrolysis of 9.65% as well as a percentage of ACE inhibition of 84.55% was attained after 300 min, and the concentration of the peptide YYQQRP required for 50% ACE inhibition was 5–10 μmol/L. The sequence analysis of the peptides was performed by ultra-high pressure liquid chromatography-time of flight mass spectrometry (UPLC-TOF-MS). YYQQRP was identified as a new peptide with potential ACE inhibitory activity by comparison with the protein database. It was hypothesized that the structure of YYQQRP might be similar to that of the substrate and could reduce the catalytic activity of ACE by binding to the active site of ACE.

Key words: sheep milk, casein, angiotensin converting enzyme inhibitory peptide, enzyme kinetic analysis, liquid chromatography-mass spectrometry

摘要： 以绵羊乳酪蛋白为原料，采用中性蛋白酶水解制备生物活性肽，研究酶解时间对酶解产物水解度和血管紧张素转换酶（angiotensin converting enzyme，ACE）抑制率的影响，利用液相色谱-质谱联用技术对水解产物进行分析和鉴定，筛选具有潜在ACE抑制作用的生物活性肽。结果表明：酶解时间达到300 min时，水解度最高值达9.65%，ACE抑制率为84.55%；当ACE抑制率达到50%时，所需肽段YYQQRP浓度为5～10 μmol/L；利用超高效液相色谱飞行时间质谱仪对酶解后的多肽进行序列分析，

关键词: 绵羊乳, 酪蛋白, 血管紧张素转换酶抑制肽, 酶动力学分析, 液相色谱-质谱联用技术