Figure 4.

MALDI-TOF profile of N-glycans from transmembrane mucins isolated from human corneal epithelial cells. The N-linked glycans were released enzymatically by PNGase F, permethylated, and profiled by MALDI-TOF mass spectrometry. Magnified portions at m/z = 1500–2500, 2500–3500, and 3500–5500 are shown. Putative structures are assigned based on compositional information and known biosynthetic pathways. Most of the N-glycans on corneal mucins have compositions consistent with bi-, tri-, and tetra-antennary complex glycans, carrying N-acetyllactosamine residues and high mannose structures. All molecular ions detected are present in the form of [M + Na]⁺.