Naturally Occurring Peptides in Human Milk: Identification and Evidence for Antibacterial Action

Abstract

For over 200 million years, milk has co‐evolved with mammalian infants to be nourishing and immunoprotective. Scientists are now realizing that milk is not simply a mixture of basic nutritional building blocks, but rather a dynamic, active and personal source of nourishment to the human infant. Fragments of milk proteins released during infant digestion have an array of biological functions within the gut and systemically including opioid‐like activity, immune system modulation and antimicrobial action. These peptides are typically inactive within the sequence of the parent protein and only become active when released by proteolysis.This study aimed to identify the extent of milk protein degradation within the breast and identify released peptides with potential bioactivity. Pooled, mature term breast milk was analyzed for presence of protein fragments by nano‐LC Chip Quadrupole Time‐of‐Flight Tandem Mass Spectrometry (Chip‐Q‐TOF). Of the 508 unique milk peptides identified, most (62%) were derived from ß‐casein. Sixty‐two peptides had significant sequence overlap with known bioactive peptides with antimicrobial or immunomodulatory functions. These 500 unique peptides represent a five‐fold increase in the number of naturally occurring peptides identified in the entire history of milk research.Grant Funding Source: USDA