29. 10. 2012 The University of Cape Town
Moore et al., (2012). Evolution of an HIV glycan–dependent broadly neutralizing antibody epitope through immune escape. Nature Medicine.
16. 05. 2013 The University of Cape Town
Go et la., (2013) Characterization of Host-Cell Line Specific Glycosylation Profiles of Early Transmitted/Founder HIV-1 gp120 Envelope Proteins
Glycosylation modulates
Difficulties of protein glycosylation analysis
ETD (electron transfer dissociation) - to complement CID (collision induced dissociation)
Ability to identify O-linked amino acids
Only CHO were phosphorylated. No HEK 293T cells were phosphorylated. Phosphorylation crucial for crossing the blood brain barrier.
O-linked CHO core1 type and HEK 293T had core 1, 2, 3 -type
Expression system crucial for pharmaco-activity, protein folding and post-translational modifications.
N-linked - NXT/S while O-linked - Threonine and Serine
Glycosylation Analysis
Determine glycan motif, extent of glycosylation
Typical Workflow
Glycopeptides are digested with a specific or nonspecific protease to generate a peptide/glycopeptide mixture that is subjected to separation or enrichment step prior to MS and tandem MS, Data analysis.
ETD combines the ability to fragment the peptide backbone while leaving the glycan modification intact. CID produces conventional glycosidic cleavages.
Deglycosylation - PNGase or EndoH
Parrish et al., (2013). Phenotypic properties of transmitted founder HIV-1