Characterization of iron-binding phosphopeptide released by gastrointestinal digestion of egg white. (January 2015)

• Record Type: Journal Article
• Authors: Palika, Ravindranadh; Mashurabad, Purna Chandra; Nair, Madhavan K.; Reddy, G. Bhanuprakash; Pullakhandam, Raghu
• Is Part Of: Food research international. Volume 67(2015)
• Page Start: 308
• Page End: 314
• Publication Date: 2015-01
• Subjects: Bioavailability -- Caco-2 cells -- De novo sequencing -- Iron-binding peptides -- In vitro digestion; Ferric chloride (PubChem CID: 23673676) -- Ferrozine (PubChem CID: 34127) -- α-Cyano-4-hydroxycinnamic acid (PubChem CID: 5328791) -- 2-(N-Morpholino) ethanesulfonic acid sodium salt (PubChem CID: 78165) -- Acetonitrile (PubChem CID: 6342) -- Ascorbic acid (PubChem CID: 54670067); Food -- Analysis -- Periodicals; Food industry and trade -- Periodicals; Food industry and trade -- Canada -- Periodicals; Food Technology -- Periodicals; Food -- Periodicals; Food-Processing Industry -- Periodicals; Aliments -- Industrie et commerce -- Périodiques; Aliments -- Industrie et commerce -- Canada -- Périodiques; Aliments -- Recherche -- Périodiques; Food industry and trade; Canada; Periodicals; Electronic journals; 664.005
• DOI: 10.1016/j.foodres.2014.11.049
• Languages: English
• ISSNs: 0963-9969

Abstract

Abstract: Binding and solubilization of ferric iron by food peptides, released during digestion, facilitate intestinal iron absorption. In the present study, we investigated the release of iron-binding peptides during in vitro gastrointestinal digestion of chicken ( Gallus gallus ) egg white. The iron-binding activity of the egg white protein increased upon gastrointestinal digestion. The iron-binding fraction of egg white digesta was purified by gel filtration chromatography followed by reverse phase HPLC. Subsequently, this fraction was identified as an internal fragment of ovalbumin (DKLPGFGDS (PO 4 ) IEAQ, 61–73 residues, GenBankAAB59956.1 ) by MALDI-MS/MS followed by de novo sequencing. The synthetic peptide corresponding to the identified iron-binding peptide sequence bound and increased the 59 Fe-iron uptake. Further, the synthetic peptide also stimulated the iron-induced ferritin synthesis in intestinal Caco-2 cells. While, dephosphorylation of synthetic peptide completely inhibited the iron-binding activity, methyl-esterification of its carboxyl groups partially inhibited the activity. These results suggest that food derived peptides modulate intestinal iron absorption and that the isolated iron-binding egg peptide could be a potential nutraceutical for improving iron absorption. Highlights: Peptides released during digestion of food proteins thought to increase the iron absorption In vitro digestion of egg proteins led to the release of iron binding peptide. The iron binding peptide was purified and characterized using sequential chromatography followed by MALDI-MS/MS. The iron-binding phosphopeptide is identified as the internal fragment of ovalbumin. The synthetic phosphopeptide increased the solubility and absorption of iron in Caco-2 cells.