The Peptide Profile And Proteomics Of Whey Protein

Whey protein is a by-product of cheese production which is a good source of a variety of active proteins and bioactive peptides and has a variety of biological functions.The processes of cheese production includes enzyme curd cheese,acid curd cheese,and fresh cheese.The composition of whey protein in cheese whey are quite different under different production process conditions.Based on the understanding of the basic composition and content of three whey protein samples from different processes(EC-WP,AC-WP and FC-WP),the peptide profile and proteomic of whey protein were studied by label-free techniques.The bioinformatics analysis was carried out on bioactive peptides and functional proteins.LC-MS/MS label-free semi-quantitative method was used for the relative quantification of whey proteins and peptides from different samples.A total of 163 peptides were identified,of which contained 104 same peptides in three samples and 59 specific peptides.The types of peptides in the enzyme brunch whey protein were the most,and acid curd whey protein had the most highest peptides.A total of 219 proteins were identified,of which contained the same 166 proteins and 53 specific proteins.Enzyme-curd cheese whey protein contained the largest number of proteins.Gene Ontology(GO)analysis results showed that 23.29% and 13.70% of whey proteins were mainly involved in transport and metabolism pocesses,respectively.Moreover,the results of KEGG revealed that the major differential proteins in the whey protein samples mainly involved in immune-related phagosomes,complement and coagulation cascades,fatty acid metabolic pathways,PPAR signaling pathways,and PI3K-AKT signaling pathways.The bioactive peptides and functional proteins in the samples were analyzed through bioinformatics analysis.14 bioactive peptides were identified using the BIOPEP database,which were mainly characterized by antibacterial,ACE inhibitory activity,mineral binding,opioid,anticancer and antioxidant activity.The primary structures and domains of zinc-alpha-2-glycoprotein and angiopoietin were predicted.The secondary structures of these two proteins include ?-helix,random coil and extended chain.Zinc-alpha-2-glycoprotein included two functional domains which were MHC I and Ig C_MHCI_alpha3.They were located in the 23-198,202-293 amino acids of Zinc-alpha-2-glycoprotein.The functional domains of angiogenin were located in the26-143,1-118 amino acids of angiogenin-1 and angiogenin-2,respectively.