Rapid Purification and Identification of Osteopontin from Human Milk by HPLC Coupled to FT-ICR-MS

Milk as a key element for infant nutrition represents the only source of feeding for newborns and infants, breast-feeding milk normally contains several bioactive proteins or peptides useful for the development of the immune system that protects infants from diseases. Osteopontin(OPN) plays a distinct role during the processes of lactation. Some studies on OPN isolated and purified from the human milk via HPLC on SCX and C(4) columns adopted biological mass spectrometry. After digesting the purified OPN sample with trypsin, the typical correlative polypeptide fragments GDSVVYGLR and QNLLAPQTLPSK are identified by FT-ICR-MS. The rapid identification of OPN is assumed to be reasonably well behaving in a standard bottom-up experiment. It shows that nano-spray HPLC combined with FT-ICR-MS and Mascot search can be used as a high efficient method for the identification of purified OPN and its polypeptide fragments. Further study will provide more academic theories of their different modifications and the bioactivity as well.