To overcome the identification challenge of low-abundance lysine acetylation (Kac), a novel approach based on a molecularly imprinted polymer (MIP) was developed to improve the extraction capacity of Kac peptides in real samples. Green deep eutectic solvents (DESs) were introduced and used as one of the synergistic functional monomers with zinc acrylate (ZnA). Glycine-glycine-alanine-lysine(ac)-arginine (GGAKacR) was chosen as a template and N,N'-methylenbisacrylamide (MBAA) was used as a cross-linker. The obtained GGAKacR-MIP had excellent selectivity for the template with an imprinting factor (IF) of up to 21.4. The histone digest addition experiment demonstrated that GGAKacR-MIP could successfully extract GGAKacR from a complex sample. Finally, the application to the extraction of Kac peptides from mouse liver protein digestion was studied in detail. The number of Kac peptides and Kac proteins identified was 130 and 110, which were 3.71-fold and 3.93-fold higher than those of the untreated sample. In addition, the number of peptides and proteins identified after treatment increased from 5535 and 1092 to 17 149 and 4037 (3.10-fold and 3.70-fold, respectively). The results showed that the obtained MIP may provide an effective technical tool for the identification of Kac-modification and peptide fractionation, as well as a potential approach for simultaneously identifying post-translational-modified proteomic and proteomic information.
Keywords: deep eutectic solvents monomer; lysine acetylation; molecular imprinting technique; post-translational modifications; solid-phase extraction.