Stability of Oyster Zinc-binding Peptides and Their Mechanism of Absorption and Transport Across Caco-2 cell Monolayers
[Objective]To investigate the stability of oyster(Crassostrea hongkongensis)zinc-binding peptides(ZnPE)in thermal and acidic or alkaline environments and the mechanism of absorption and transport across the Caco-2 cell monolayers model,and the conclusions may provide theoretical basis for the development of zinc supplements.[Methods]Using oyster zinc-chelating peptides(Zn-PE)and ZnSO4 as control,the stability of ZnPE was evaluated by the solubility indexes of total Zn and Zn ions at 40,50,60,70 and 80℃,and at pH values of 2,4,6,8,and 10;a Caco-2 cell monolayer model was established to study the absorption rate,bioavailability,and transport pathway of ZnPE across Caco-2 cell monolayer model.The sequence changes of ZnPE across Caco-2 cell monolayers were investigated by liquid chromatography-mass spectrometry(LC-MS/MS).[Results]Under different temperatures,there was no significant difference in the solubility rates of total zinc and zinc ions in ZnPE and Zn-PE(P>0.05),and both of them could maintain a high stability.In acidic environment(pH=2),the solubility rate of total zinc in both ZnPE and Zn-PE was above 90%,while there was a slight release of zinc ions with the solubility rate of 22.30%and 33.45%,respectively,and the stability of both of them was reduced but the stability of ZnPE was significantly higher than that of Zn-PE(P<0.05).While in alkaline environment(pH=8),both ZnPE and Zn-PE remained stable.The ZnPE could completely and stably pass through Caco-2 cells monolayers model,and its zinc absorption was 74.37%and bioavailability was 76.40%,which were significantly higher than that of Zn-PE and ZnSO4(P<0.05).The zinc in the ZnPE was transported across the Caco-2 cell monolayers model mainly in the form of peptides through cell bypass by means of transcytosis.Eight zinc-binding peptides were identified after transport,five of which were consistent with those before transport,suggesting that ZnPE can maintain high stability in absorption and transport.[Conclusion]ZnPE can maintain high stability in thermal and acrid/alkaline environments and during transport across the Caco-2 cell monolayers model.
oysterzinc-binding peptidesstabilityCaco-2 cellsabsorption and transport
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