Protein deamidaNon is a non-enzymaNc PTM that occurs in proteins via the removal of an amide group due to a conversion of asparagine or glutamine to an aspartate or glutamate residue . This reacNon takes place via a succinimide intermediate that then is hydrolysed into a mixture of aspartate and isoaspartate. This results in a mass ship of 0.98 Da acributed to mass difference between a NH2 and a OH group. DeamidaNon of biotherapeuNcs can result in negaNve consequences leading to protein stability and efficacy issues , hence deamidaNon is an important CQA to monitor within the QC environment.