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. 2024 May 28;11(7):nwae183. doi: 10.1093/nsr/nwae183

Figure 4.

Figure 4.

AmproCode for Aβ detection from complex mixtures. (a) Transpeptidase SrtAβ-mediated Aβ modification for AmproCode. In a complex sample, SrtAβ recognizes the LMVGG sequence in the Aβ peptide and conjugates GGG-TAMRA to it. The product Aβ-TAMRA can be applied in the AmproCode workflow. (b) HPLC analysis of the sample mixture after labeling Aβ with TAMRA. The absorption spectra are chosen at 200 and 353 nm (TAMRA-specific absorption). (c) Mass spectrum of Aβ-TAMRA. The theoretical molecule weight (MW) is 4786 Da and the observed MW is 4787 Da. (d) Identification of Aβ peptide via AmproCode using the composition code of Cys, Lys, Met and Tyr. qPCR quantified composition code of Aβ is 0.00:1:0.34:0.33 (Cys:Lys/N-terminal:Met:Y) at 108 copies/μL (average of three independent replicates). After matching this composition code with the code library from the secretome, Aβ (protein entry: A4) can be identified in the top four candidates with the highest score.