Effect Of Soybean-whey Plastein On Capacity Of Binding Bile Acid

Cardiovascular disease(CVD)was a key cause of high morbidity and mortality in the world,and associated with level of blood lipoids.Binding bile acid in the intestinal tract could decrease the serum cholesterol level.It was reported that protein hydrolysate had the capacity of binding bile acids,which contributed to cholesterol lowering.Plastein reaction,one type of enzyme modify on protein,could enhance biological activities of parent hydrolysate.Soy protein and whey protein were nutritive plant protein and animal protein respectively.Peptides of them have important bioactivity.In this study,palstein reaction was used to combine the advantages of soybean protein and whey protein,and then modified the capacity of bile acid binding.Firstly,soybean protein and whey protein were hydrolysed and the hydrolysis condition was optimized.The condition of soybeea protein was concentration 4%,enzyme ratio 1.5 KU/g pro,pH 2.0,40?,5.0 h.The condition of whey protein was concentration 5%,enzyme ratio 1.0KU/g pro,pH 2.0,37 ?,5.0 h.The degree of hydrolysis was 11.63%and 7.,pepsin was used to modify plastein reaction.The decrease of free amino gro94 respectively.Secondlyups and the turbidity were selected as a standard to study the effect of condition on plastein formation.Results showed that plastein formed preferably at condition of hydrolysate concentraton40%(Soybean Protein:Whey Proteinl:1),enzyme ratio2.0KU/g pro,pH 5.0,37? for 3.0 hours.The decrease of free amino groups was 119.67?mol/g pro.The capacity of bile acid binding of the plastein was studied.Results showed that the palstein reaction enhanced the bile acid binding capacity of two hydrolysates.The amount of binding bile acid of sodium deoxycholate,sodium taurocholate and sodium cholate was 0.75?mol/100mgpro,2.0 ?mol/100mgpro,1.87 ?mol/100mgpro respectively,and was 19.3%,10.5%,15.5%of cholestyramine(positive control).The capacity of plastein product had no decreased significantly after digestion.The FIIR showed that the amide structure of the plastein product could be affected after binding.Finally,The physical and chemical properties of the palstein product were studied.Tricine-SDS-PAGE and Native-PAGE demonstrated that plastein had new aggregation.The portion separated by Native-PAGE was identified by NanoLC-ESI-MS/MS,the ingredient of two hydroysate ?-conglycinin,? lactoglobulin and GlyCAM 1)was found.Fluorescence spectra and intermolecular forces assay showed that hydrophobic force play a key role for plastein aggregation.Amino acid analysis showed that the content of hydrophobic amino acid and hydrophobic amino acid were higher than two hydrolysate.Thus,hydrophobic force was responsible for the aggregation of soybean protein hydrolysate and whey protein hydrolysate.The plastein reaction can enhance the bile acid binding capacity of protein hydrolysate.This study can help to develop functional food.