Isolation of a Bifidogenic Peptide from the Pepsin Hydrolysate of Bovine Lactoferrin

Abstract

ABSTRACTLactoferrin is an iron-binding glycoprotein found in the milk of most mammals for which various biological functions have been reported, such as antimicrobial activity and bifidogenic activity. In this study, we compared the bifidogenic activity of bovine lactoferrin (bLF) and pepsin hydrolysate of bLF (bLFH), isolated bifidogenic peptide from bLFH, and investigated the bifidogenic spectra of bLF, bLFH, and its active peptide against 42 bifidobacterial strains comprising nine species. AgainstBifidobacterium breveATCC 15700T, minimal effective concentrations of bLF and bLFH were 300 and 10 μg/ml. AgainstBifidobacterium longumsubsp.infantisATCC 15697T, the minimal effective concentration of bLFH was 30 μg/ml, and bLF did not show bifidogenic activity within 300 μg/ml. As an active peptide, a heterodimer of A1-W16and L43-A48linked by a disulfide bond was isolated. Previously, this peptide was identified as having antibacterial activity. An amino acid mixture with the same composition as this peptide showed no bifidogenic activity. The strains of each species whose growth was highly promoted (>150%) by this peptide at 3.75 μM were as follows:B. breve(7 out of 7 strains [7/7]),B. longumsubsp.infantis(5/5),Bifidobacterium bifidum(2/5),B. longumsubsp.longum(1/3),Bifidobacterium adolescentis(3/6),Bifidobacterium catenulatum(1/4),Bifidobacterium pseudocatenulatum(0/4),Bifidobacterium dentium(0/5), andBifidobacterium angulatum(0/3). Growth of none of the strains was highly promoted by bLF at 3.75 μM. We demonstrated that bLFH showed stronger bifidogenic activity than natural bLF, especially against infant-representative species,B. breveandB. longumsubsp.infantis; furthermore, we isolated its active peptide. This is the first report about a bifidogenic peptide derived from bLF.