Absorption Mechanism Across Intestinal Of Whey Polypeptides Using Caco-2 Cell Model

Whey protein is generated in the production of cheese and casein.It is a kind of high nutritional value of protein that not only easy to be digested and absorbed,but also has high metabolic efficiency and biological value.Whey peptides have high biological activities and easy to be transported,absorbed and utilized by human body.However,not all of peptides can be absorbed by the intestine.So,researching the structure characteristic of whey peptides which can be intact absorbed into intestine can lay the foundation of downstream application of whey peptides.The Caco-2 cell model was established to explore the characteristic and sequence of amino acids that can be absorbed by small intestine in a complete form and study the influence of peptidase inhibitors on transport of whey peptides.First,whey protein was hydrolyzed by the alkaline protease,trypsin,and chymotrypsin at optimum temperature and pH value.Enzymatic hydrolyzates were ultrafiltrated by ultrafiltration membrane at 10000 Da and isolated by Sephadex G-10.Whey protein peptides with different molecular weight were produced.Secondly,the Caco-2 cell model was evaluated by morphology feature,transepithelial electrical resistance and the transmittance of fluorescein sodium.The results showed that Caco-2 cell monolayer can be used as a model of small intestinal epithelium with good integrity and cell polarity.Caco-2 cell can be used to study the intestinal absorption mechanism.Thirdly,Caco-2 cell model was used to explore the amino acids sequence characteristic of peptide which can be absorbed by small intestine in a complete form.The results showed that dipeptide(AH,EV,LK,VY,SF,TF,YL,LL,LF),tripeptide(LVG,ALK,FDK,GLF,AEK,KLD,VEE),tetrapeptide(AVFK,ALPM,KDLK)and pentapeptide(HTSGY)can be absorbed in a complete form.The neutral peptide had the highest transportation amount among the same length group.However,with the increasing of chain length,the impact of net charge was reduced.At the same time,the peptides which can be absorbed by intestine had high hydrophobic value.Last,a-lactalbumin,?-lactoglobulin and whey polypeptides produced by chymotrypsin were examined to measure the peptidase activity through the Caco-2 cell model.Result of experiment showed that peptidase had obvious enzymatic hydrolysis activity and bacitracin as a kind of protease inhibitor can effectively inhibit the enzymatic hydrolysis of peptidase.