Study On Angiotensin-converting Enzyme Inhibitor Peptide Derived From Grass Carp Protein By Enzymatic Hydrolysis

In this paper, using the alkaline protease enzyme to hydrolysis the grass carp to make angiotensin converting enzyme (angiotension-I converting enzyme, EC3.4.15.1 called ACE) inhibition of blood pressure-lowering peptides.Respectively on the RP-HPLC (RP-HPLC) Determination of ACE inhibition rate and the spectrophotometer Determination of ACE inhibition of in vitro testing methods to compare research:(1) A high performance liquid chromatographic method to determine angiotensin converting enzyme inhibitor activity in vitro was established by using hippuryl-His-Leu tetrahydrate as the reaction substrate and hippuric acid as the reaction product. The detection limit Was 0.50mmol/L.The recoveries of hippuric acid ware average 90.3%,with a relative standard deviation (RSD)0f 2.20% (n=6) . It is a simple , precise and reliable as say method for developing antihypertension drugs.the spectrophotometer Determination of ACE inhibition of the experimental .The results showed that spectrophotometer Determination of ACE inhibition rate has good accuracy and reproducibility, and the experiment is easy to operate fast, can be used for the samples of ACE inhibition rate of detection. A reliable assay method of ACE inhibitory peptides with high accurance and repeatability was modified and established, and it can be used to determine the ACE inhibitory activities of all kinds of samples.(2) Taking ACE inhibitory activity as index, after screening of several commercial proteases, alcalase was used to hydrolyze grasscorp for production of ACE inhibitory peptides.Taking ACE inhibitory activity and the degree of hydrolysis as indexes, orthogonal rotational regression design was used to optimizethe hydrolysis conditions of grasscorp protein with alcalase. The optimal hydrolysis conditions of fish were: concentration of fish protein with 35%, PH8.5,temperature 50℃, ratio of alcalase to fish protein with E:S为2%, 180min. (3) Ultrafiltration was applied to isolated ACE inhibitory peptides.The optimal ultrafiltration condition for 6KDa membrance was at 25℃with pressure 0.1MP and time 15min. After ultrafiltration the ACE inhibitory activities of the permeates and potentates separately increased 11.41%.Salt was removed by ion exchange resin at a flow rate of 3.0ml/min with desalinization rate of approximate 78% and nitrogen recovery rate of 80%. No differences were observed on the ACE inhibitory activity of samples.(4) After the process of enzymatic hydrolysis and ultrafiltration and desalinization the grass carp antihypertensive peptide was determited the physical and chemical indicators and determination found hypotensive peptide has a good solubility which will not be impacted by the pH and its favorable Application in food. Fish hypotensive peptide molecular weight distribution narrower. Its molecular weight distribution in the range between 142 ~ 21281 Da, and are mainly concentrated in the 142 ~ 738 Da ,between the molecular weight in the 738 ~ 329 Da and 329 ~ 142 Da between the components in respectively 27.80% and 34.21 %.