Fishing out Methionine-Containing Proteins from Complex Biological Systems Based on a Non-Enzymatic Biochemical...

Nowadays, it still remains a great challenge to develop a simple, fast, and low-toxic method for identification and separation of proteins from complex biological systems. Herein, a nanocomposite (Fe₃O₄@Au-Se-peptide) was designed and synthesized to fish out methionine-containing proteins based on a non-enzymatic biochemical reaction, which couples amino groups of lysine with the S-methyl group of methionine in the presence of HOBr. Peptides which contain four lysine residues (Lys-Lys-Lys-Lys-{Se-Cys}) linked to the Fe₃O₄@Au nanocomposites were used to capture methionine residues efficiently via a S═N cross-linking. The methionine-containing protein was obtained by magnetic separation and released from the Fe₃O₄@Au-Se-peptide nanocomposites with the influence of H₂Se. The HRMS and SDS-PAGE results confirmed the methionine-containing protein could be successfully fished out from a mixture solution. This work provides a useful strategy for recognition and separation of a category of proteins from complex biological systems.