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. Author manuscript; available in PMC: 2018 Aug 30.
Published in final edited form as: J Am Chem Soc. 2017 Aug 16;139(34):11670–11673. doi: 10.1021/jacs.7b05125

Figure 3.

Figure 3

Chemoselective protein labeling using 5HTP-directed azo-coupling reaction. (A) Incubating 10 μM sfGFP-151-5HTP with 40 μM 4CDz at room temperature for 30 min results in complete protein labeling (expected mass 27784 Da). (B) The wild-type protein does not undergo modification upon the same treatment. (C) Structures of the fluorescent diazonium compound 7, and the biotin-triazabutadiene conjugate 8, synthesized for protein labeling through CRACR. (D) Selective fluorescence-labeling of sfGFP-151-5HTP by 7, shown by fluorescence imaging following SDS-PAGE. (E) Selective biotinylation of sfGFP-151-5HTP using photolyzed 8, revealed by Western blot (using a streptavidin-HRP probe) following SDS-PAGE.