title: Predicting the important enzymes in human breast milk digestion.
abstract: Human milk is known to contain several proteases, but little is known about whether these enzymes are active, which proteins they cleave, and their relative contribution to milk protein digestion in vivo. This study analyzed the mass spectrometry-identified protein fragments found in pooled human milk by comparing their cleavage sites with the enzyme specificity patterns of an array of enzymes. The results indicate that several enzymes are actively taking part in the digestion of human milk proteins within the mammary gland, including plasmin and/or trypsin, elastase, cathepsin D, pepsin, chymotrypsin, a glutamyl endopeptidase-like enzyme, and proline endopeptidase. Two proteins were most affected by enzyme hydrolysis: β-casein and polymeric immunoglobulin receptor. In contrast, other highly abundant milk proteins such as α-lactalbumin and lactoferrin appear to have undergone no proteolytic cleavage. A peptide sequence containing a known antimicrobial peptide is released in breast milk by elastase and cathepsin D.
authors.affiliation: Conway Institute of Biomolecular and Biomedical Research, School of Medicine and Medical Sciences and ‡Complex and Adaptive Systems Laboratory, University College Dublin , Dublin, Republic of Ireland.
authors.forename: Nora
authors.initials: N
authors.lastname: Khaldi
authors.forename: Vaishnavi
authors.initials: V
authors.lastname: Vijayakumar
authors.forename: David C
authors.initials: DC
authors.lastname: Dallas
authors.forename: Andrés
authors.initials: A
authors.lastname: Guerrero
authors.forename: Saumya
authors.initials: S
authors.lastname: Wickramasinghe
authors.forename: Jennifer T
authors.initials: JT
authors.lastname: Smilowitz
authors.forename: Juan F
authors.initials: JF
authors.lastname: Medrano
authors.forename: Carlito B
authors.initials: CB
authors.lastname: Lebrilla
authors.forename: Denis C
authors.initials: DC
authors.lastname: Shields
authors.forename: J Bruce
authors.initials: JB
authors.lastname: German
mesh_terms: D004063:Digestion; D004798:Enzymes / Q000378:metabolism*; D020869:Gene Expression Profiling; D006801:Humans; D013058:Mass Spectrometry; D008895:Milk, Human / Q000378:metabolism*
chemical_list: D004798:Enzymes