A few of the fragments detected in AAV6 and AAV9 were the result of truncation of the C-terminus of (Ac)VP3. The largest of these fragments is due to the cleavage of the DP peptide at D590 and D657 in AAV6 and AAV9, respectively, through hydrolysis of the aspartic acid, which can occur in acidic conditions . It is possible that these fragments are related to the analysis conditions used as the BGE used during sample preparation and analysis has a pH around 2.4. The smaller (Ac)VP3 fragments in AAV9 are not caused by the hydrolysis of the aspartic acid but might be the result of further degradation at that end once the hydrolysis occurred.