Glycome characterization of immunoglobulin G from buffalo (Bubalus bubalis) colostrum

Immunoglobulin G (IgG) is a major glycoprotein in ruminant colostrum. First day buffalo colostrum protein was purified on Sephadex G-100 and its mass was determined by MALDI-TOF as 147.848 KDa. The PMF data of protein subunits revealed its homology to IgG, which was supported by the identification of peptide sequences LLIYGATSR and VYNEYLPAPIVR corresponding to light and heavy chains of IgG by CID MS/MS analysis. The N-glycan microheterogeneity was established based on chemoselective glycoblotting technique with the identification of high mannose, neutral complex/hybrid and sialylated complex/hybrid glycans. A complete structural assignment of 54 N-linked oligosaccharides were identified and the ratio of sialyl oligosaccharides was found to be higher compared to neutral saccharides. The fucosylation observed in more than 20 oligosaccharides, high mannose and trisialyl oligosaccharides were present in diminutive amount. The high non-fucosyl and sialyl oligosaccharides in buffalo colostrum IgG provide ample scope for its utilization in targeted therapies to elicit effective ADCC and anti-inflammatory responses.