Structural characterization of the N-linked oligosaccharides in bile salt-stimulated lipase originated from human breast milk

Abstract

The detailed structures of N-glycans derived from bile salt-stimulated lipase (BSSL) found in human milk were determined by combining exoglycosidase digestion with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. The N-glycan structures were conclusively determined in terms of complexity and degree of fucosylation. Ion-exchange chromatography with pulsed amperometric detection, together with mass-spectral analysis of the esterified N-glycans, indicated the presence of monosialylated structures. The molecular mass profile of esterified N-glycans present in BSSL further permitted the more detailed studies through collision-induced dissociation (CID) and sequential exoglycosidase cleavages. The N-glycan structures were elucidated to be complex/dibranched, fucosylated/complex/dibranched, monosialylated/complex/dibranched, and monosialylated/ fucosylated/dibranched entities.