A highly selective fluorescent ESIPT probe for the dual specificity phosphatase MKP-6

A highly selective fluorescent probe for a protein tyrosine phosphatase (PTP) was designed by a simple phosphorylation of the 2-(2'-hydroxyphenyl) benzothiazole (HBT) chromophore: upon selective enzymatic hydrolysis, an excited-state intramolecular proton transfer (ESIPT) occurs, resulting in a large Stokes shift.