Exploration of Bovine Milk Proteome in Colostral and Mature Whey Using an Ion-Exchange Approach

In addition to milk's nutritional role, it contains immunoglobulins (antibodies) and immunoregulatory proteins that are active in the digestive tract of newborns. However, knowledge of the repertoire of milk proteins remains meager. In this work, we report an ion-exchange-based protein fractionation method that allows in-depth exploration of the whey proteome in bovine milk; 293 unique gene products were identified, of which 176 were newly identified in whey. This work also demonstrated qualitatively for the first time the consistency, albeit differing in protein levels, in milk proteome between colostrum and mature milk (3 mo. post calving). Semiquantitative analysis showed a number of up-regulated proteins in colostrum that may provide extra natural defenses for the neonate. Increased understanding of the composition and functions of bovine milk proteins and their potential health benefits may, in the future, play an important role in nutritional and biomedical applications as properly processed cow's milk proteins could potentially confer the same bioactivity as their human counterparts.