Preparation And Purification Of ACE Inhibitory Peptide By Enzymolysis From Vinegar-egg And Its Active Preserve

Vinegar egg is as a traditional diet and healthy food,mainly made from eggs and vinegar,is popular for its simple fabrication technique,high nutritional value,immunity-reinforcing effectsin folk.Active peptide in vinegar egg has the ability of inhibiting angiotensin converting enzyme activity and preventing hypertensive disease.Basis on the traditional fabrication technique of vinegar egg,ACE inhibitory peptide was prepared by enzyme hydrolysis and the process parameters was optimized in this research.ACE inhibitory peptide in vinegar egg was separated and purified by ultrafiltration and gel chromatography due to obtain a highly active ACE inhibitory peptide.And then ACE inhibitory peptides was bound with lecithinsdue to protect their activities,and the binding state between peptides and lecithins have been studied by infrared absorption spectrum and XRD.The main conclusions are as follows:1.Optimization of enzymatic preparation of ACE inhibitory peptideThrough the ortheogonal optimization experiment,the degree of hydrolysis and IC₅₀was as optimizing index,and the optimal enzymatichydrolysis condition including enzyme temperature,enzyme amount and enzyme time were 50?,1%,3h,respectively.And under the optimal condition the vinegar egg juice was hydrolyzed and the results showed that the degree of hydrolysis and IC₅₀were 31.53?±1.02?%and 29.48?±0.71??g/mL.2.Separation and purification of ACE inhibitory peptide in vinegar eggUltrafiltration was used to separate the vinegar egg juice,and the results showed that enzymatic hydrolysate with molecular weight less than 1 KDa had a higher inhibitory activity.And then ACE inhibitory peptide within this molecular weight range was purified by gel chromatography to obtain the component including high ACE activity.3.Analysis of lecithin-peptide complex by infrared absorption spectrum and XRDThe results of infrared absorption spectrum showed that there was an interaction between active peptide and lecithin.Moreover,XRD results indicated that carboxyl and amino of active peptide occurred in combination with lecithin in the form of coordination bond,resulting in active peptide in the amorphous or molecular state form exist after being absorbed by lecithin.4.Stability of lecithin-peptide complexEffects of pH,temperature and various metal ions on the stability of lecithin-peptide complex have been investigated,and the results showed that the complex had a better stability in the pH 3¹1,temperature less than 40?and Ca²⁺?K⁺?Mg²⁺situations.Furthermore,the inhibiting activity on ACE of active peptide and lecithin-peptide complex has been compared in vitro,and the results showed that the degradation of active peptide after compound treatment could be well prevented from the gastrointestinal enzymes.