Posttranslational modifications (PTM) of proteins are generally not addressable with current peptide and protein arrays on the market. PTMs often affect protein-protein interactions and disease-associated autoantibodies are excellent examples of this. Aberrant PTM modifications such as citrullination in rheumatoid arthritis lead to induction of autoantibodies directed specifically to the PTM-peptide epitope.
GlycoZym has identified a large number of proprietary O-PTM peptide epitopes recognized by cancer-associated autoantibodies. These autoantibodies do not recognize unmodified peptides or peptides modified the way normal cells do. Most commercially available protein arrays display proteins without PTMs or with PTMs different from what is found in human diseases.
For example, E.coli produced recombinant proteins fail to present most types of PTMs, while insect cells produce recombinant proteins with different PTMs than man. To overcome this GlycoZym is building PTM-peptide libraries designed to capture disease-associated PTM variants. Therefore GlycoZym’s O-PTM glycopeptide library displays peptides with known cancer-associated O-glycoforms.