Fig. 1. Design principle and sequence of the FRET-based probe, A-1. (a) FRET responses of A-1 in the absence and presence of Zn(ii) with and without inhibitors. (b) Amino acid sequence of A-1. A-1 is composed of Trp (blue box) at the C-terminus as a FRET donor and 1-naphthylethylenediamine conjugated to the side chain of the Asp (orange box) at the N-terminus as a FRET acceptor. Proposed amino acid residues for metal binding and a portion of the self-recognition site are indicated in green and red, respectively.
