Breast Milk Proteases

Abstract

The proteins contained in milk carry out a broad array of complicated biological functions. Some proteins in milk have one function in their intact form, whilst also containing a sequence of latent function that becomes active following splitting of the main peptide chain. This bioactivity may involve attacking harmful microbes in the gut as well as regulating the infant's immune response. Thus, they may confer an evolutionary advantage. Current evidence suggests that this unmasking of latent bioactivity actually begins even, whilst milk is still within the breast. A range of proteolytic enzymes (proteases) in milk act on proteins in the milk to produce these bioactive peptide sequences. Furthermore, these same enzymes retain their functionality in the infant's intestine, potentially performing a more important catalytic function than even the proteases secreted by the infant's developing gut. This may reflect the fact that newborn infants are somewhat inefficient in digesting milk unless assisted by the proteases present in milk. The bioactive sequences latent in certain milk protein precursors are released through a series of steps involving both milk-derived proteases and proteases secreted by the infant gut. One of the aims of research is to understand how this release of latent bioactivity orchestrated through protease activity contributes to an evolutionary advantage for the mother and child [1, 2]. © Springer Nature Switzerland AG 2023. All rights reserved.