FIGURE 3.

Identification of α-synuclein as an O-GlcNAcylated protein in the mouse brain by mass spectrometry. 10 mg wet hippocampal tissues were processed and digested by trypsin. Protein digests containing O-GlcNAc peptides were identified by the chemical/enzymatic photochemical cleavage method in which O-GlcNAc was tagged with the aminomethyltriazolacetylgalactosamine (AMT-GalNac). The labeled O-GlcNAc peptides were identified with the high-energy collisional dissociation (HCD) method. The letter “g” indicates the neutral loss of the entire AMT-GalNac-GlcNac moiety. This is a representative peptide identified as α-synuclein amino acid 58–77 with T75 O-GlcNAcylated.