Fig. 3. Structure-based “step by step” rational design of β-gal fluorescent probes. (a) Structures of KSL01–KSL04 with EWGs on the 3′-position. (b) Structures of KSL05–KSL12 with EWGs on the 5′-position. “+” means that the probe could be hydrolysed by the corresponding β-gal; “−” means that the probe could not be hydrolysed by the corresponding β-gal; “±” means KSL07 responded slowly to E. coli β-gal. (c) Excitation wavelength (λex) and maximum emission wavelength (λem) of KSL01–KSL12.
