鲢鱼ACE抑制肽的生化特性及其降压功能

The biochemical characteristics and antihypertensive function of ACE inhibitory peptide from silver carp

利用高效液相色谱法、基质辅助激光解吸质谱法及氨基酸自动分析系统,测定分析了鲢鱼Hypophthalmichthys molitrix血管紧张素转换酶（ACE）抑制肽的相对分子质量分布及氨基酸的组成,并通过对自发性高血压大鼠（SHR）进行的降血压试验,检测了鲢鱼ACE抑制肽的降压活性,分析了其生化特性与降压功能的关系。结果表明：鲢鱼ACE抑制肽的相对分子质量在1.6×103以下,其中10肽以下短肽所占的比率约为49.66%,这些短肽对ACE抑制肽的降压效果有显著影响;每百克ACE抑制肽样品中含游离氨基酸的量为8.8 g,含水解氨基酸的量为59.6 g,同时含与ACE受体紧密结合、维持其高活性所必需的疏水性氨基酸的量为24.86 g;按照3.0 g/kg剂量给SHR喂饲ACE抑制肽样品后,其血压在2~6 h内平均降幅为2.394~3.724 kPa（18~28 mmHg）（а=0.05）,在喂饲6h时,其降压幅度达到最大值,为3.724 kPa（28 mmHg）。可见,从鲢鱼中提取高活性的ACE抑制肽作为治疗高血压症的药品原料,有望在未来的研究中得到进一步开发。

Angiotensin-converting enzyme（ACE） inhibitory peptide is one of the bioactive peptides which can reduce the blood pressure effectively,This activity is mainly due to the inhibiton of the angiotensin I-converting enzyme,which plays 2 important roles in the regulation of blood pressure.One is to convert inactive decapeptide angiotension into strong vasoconstrictor and saltretaining octapeptide,angtiotensin Ⅱ.The other is to inactivate vasodilator and natriuretic nonapeptide,bradykinin.Silver carp,a kind of freshwater fish,is abundant and inexpensive in China.Because of the coarse flesh and plenty of small prickle,silver carp is usually not used for direct cooking.Only small amount is used for process of fish gruel and pellet,the great part is used as coarse feed and bait material.At the same time,because of the backward processing and storage technology,large amount of silver carp goes rotten for not being timely treated,which results in resources waste and serious pollution.The project is using silver carp,as the raw material to make ACE inhibitory peptide.The relative molecular mass,amino acids composition and antihypertensive function of ACE inhibitory peptide are studied,and the relationship between its biochemical characteristics and antihypertensive function analysed.The results show that the molecular mass of ACE inhibitory peptide is below 1.6×103,the short peptides below decapeptide makes up 49.66% which have significant influence on the antihypertensive function.Furthermore,the free amino acids content in ACE inhibitory peptide is 8.8%,the total hydrolysate of amino acids is 59.6%,and the hydrophobic amino acids is 24.86%,which shows that the composition ratio of the amino acid is in balance with rich essential ones and the content of glutamic acid is the highest of 8.57%.At last,SHR fed with 3.0 g/kg weight ACE inhibitory peptide showed obvious antihypertensive function within 2 to 6 hours,the average reduced breadth was 2.394~3.724 kPa（18~28 mmHg）（а=0.05）.The ACE inhibitory peptide from silver carp protein could be used as functional food ingredients with potential therapeutic benefit in the prevention and treatment of hypertension.