Study On Preparation And Property Of Biological Active Peptides Derived From Whey Protein With Capacity Of Decreasing The Level Of Cholesterol In Serum

The present study was designed to prepare biological active peptides derived from whey protein with the capacity of decreasing the level of cholesterol in serum.The degree of hydrolysis(DH) was chosen as index to optimize the condition parameter of five whey protein hydrolysis mode with trypsin and A.S1398 neutral protein enzyme.For screening right mode and condition parameter of hydrolysis producing the target biological active peptides, detecting the activity of HMG-CoA reductase in vitro was taken as the criterion. The target biological active peptides was separated and the range of its molecular weight was determined also.Mice feeding experiment was arranged for estimating the practical value of the biological active peptides separated.1. In order to determine the right mode and condition parameter of hydrolysis for producing the biological active peptides derived from whey protein we wanted,Center combination experimental design, orthogonal experiments design and singl factor experiments design were used,then the effect of hydrolysate in different phases of every hydrolysis mode on HMG-CoA reductase activity were measured.The result indicated that the hydrolysate in(8+1)hours phase of the mode of which the adding sequence is A.S1398 neutral protein enzyme following trypsin represents comparatively high restraining ability to HMG-CoA reductase activity,the percentage of HMG-CoA reductase activity inhibited is 13.01% with concentration of the hydrolysate 50mg/ml.2. For separating the target biological active peptides from the mixture ,the CM-Sephadex C50 possessing the Iron-Exchange and Size-Exclusion property was designated as chromatography material.The appropriate eluting condition parameter were determined with the pH(6.0～8.0) linearity grads eluting mode and three phosphate buffer ion density(10mmol/L,30mmol/L,50mmol/L). The result showed that the hydrolysate could be successfully detached four independent ingredient by CM-Sephadex C50 with pH(6.0～8.0) linearity grads eluting mode and 30mmol/L phosphate buffer ion density,and the percentage of HMG-CoA reductase activity inhibited by the fourth constitutes could reachs 17.25% with concentration 50mg/ml.The molecular weight range of target biological active peptides was identified by SDS-PAGE with 3% stacking gels and 17.5% running gels,the result exhibited that the molecular weight range of target biological active peptides between 2000 and 12000.3. To estimate the practical virtue of the biological active peptides separated,forty male Kunming mice having no distinct difference(p>0.05) in body weight were divided into four groups.In addition to the basic daily feed,each group were treated according the schedule:A group were fed with clean water, B group whey protein solution, C group the first and second constitutes divided, D group the third and fourth constitutes divided,and the concentration of free nitrogen in the feeding liquid of groupB,C and D were same.The result proved that,in comparison with other material fed, the target biological active peptides could powerfully decline the level of TC in serum(p<0.05),decrease the concentration of plasma TG and lessen the TC-LDL/HDL. Moreover, the target biological active peptides also exhibited the capacity of promoting growth and reducing fat deposition significantly(p<0.05).