Disorder in Milk Proteins: Formation, Structure, Function, Isolation and Applications of Casein Phosphopeptides

This article is a continuation of a series of reviews on the presence and the role of intrinsic disorder in milk proteins in the journal of Current Protein and Peptide Science. The focus of this article is on casein phosphopeptides, which are liberated during digestion of the milk protein casein. Structurally these phosphopeptides have multiphosphorylated regions making them highly charged. The high degree of charge coupled with relatively low instances of hydrophobic amino acids makes them intrinsically disordered. These peptides have anticariogenic, antimicrobial, immunomodulatory, and cytomodulatory properties. Recent work using in vivo and in vitro models suggests that in addition to transporting calcium, these peptides can also enhance its bioaccessibility. The mechanism of this enhancement has yet to be determined. We review the current state of their structure, function, and isolation of these peptides.