title: A general way to assay protein by coupling peptide with signal reporter via supermolecule formation.
abstract: Protein-binding peptide is recently recognized as an effective artificial affinity reagent for protein assays. However, its application is hampered by the limited choices of available signal readout methods. Herein, we report a general electrochemical signal readout method for protein-binding peptides exploiting the host-guest chemistry of cucurbituril. Via the formation of supermolecules among cucurbituril, electrochemical reporter, and the peptide, a protein-binding peptide can be noncovalently coupled with the electrochemical reporter. To assay the target protein, the protein-binding peptides are first self-assembled in the sensing layer, and after the capturing of the target protein, a portion of the peptides become protein-bound. The protein-free peptides are then coupled with the electrochemical reporter to yield a signal readout inversely proportional to the amount of the captured target proteins. Since the only requirement of supermolecule formation is the incorporation of aromatic amino acids in the peptide sequence, this strategy is universally applicable to many protein-binding peptides. The generality and target specificity of the proposed method are successfully demonstrated in the assays of two kinds of target proteins: tumor necrosis factor-α and amyloid β 1-42 soluble oligomer, respectively. The feasibility of our method is also tested in the monitoring of tumor necrosis factor-α secretion activity of HL-60 cells. These results indicate that our method can have great use in protein detection in the future.
authors.affiliation: Department of Biochemistry and State Key Laboratory of Pharmaceutical Biotechnology, Nanjing University, Nanjing 210093, PR China.
authors.forename: Hao
authors.initials: H
authors.lastname: Li
authors.forename: Haona
authors.initials: H
authors.lastname: Xie
authors.forename: Ya
authors.initials: Y
authors.lastname: Cao
authors.forename: Xiaorong
authors.initials: X
authors.lastname: Ding
authors.forename: Yongmei
authors.initials: Y
authors.lastname: Yin
authors.forename: Genxi
authors.initials: G
authors.lastname: Li
mesh_terms: D016229:Amyloid beta-Peptides / Q000032:analysis*; D004566:Electrodes; D006046:Gold / Q000737:chemistry; D018922:HL-60 Cells; D006801:Humans; D046911:Macromolecular Substances / Q000138:chemical synthesis / Q000737:chemistry; D010446:Peptide Fragments / Q000032:analysis*; D010455:Peptides / Q000032:analysis*; D013499:Surface Properties; D014409:Tumor Necrosis Factor-alpha / Q000032:analysis*
chemical_list: D016229:Amyloid beta-Peptides; D046911:Macromolecular Substances; D010446:Peptide Fragments; D010455:Peptides; D014409:Tumor Necrosis Factor-alpha; C075222:amyloid beta-protein (1-42); D006046:Gold