“Domain Directional Optimization” strategy for the development of UGT1A1-activated fluorescent probe and the application in living systems

Activity-based fluorescent probes have emerged as the powerful tool for directly monitoring enzyme activity in living systems. Whereas, constructing high isoform-specific fluorescent probes for a target isoenzyme with multiple subtypes is still facing challenge. UGT1A1, as an isoform of UGTs, is a clear target for neonatal jaundice, irinotecan-induced toxicity, and fatal Crigler-Najjar syndrome type I. Herein, a “Domain Directional Optimization” strategy was proposed based on the systematic computational chemistry and synchronously experimental verification. Finally, an isoform-specific “switch-on” fluorescent probe (BUHE) was developed for UGT1A1 based on the boron-dipyrromethene (BODIPY) skeleton. BUHE exhibited the high selectivity and sensitivity toward UGT1A1 and the catalytic progress followed typical Michaelis-Menten kinetic. Moreover, BUHE had a good biocompatibility and chemical stability which was successfully applied to the activity evaluation and in situ imaging of UGT1A1 in complicated bio-systems including living cells, tissue slices and whole organs. In summary, the “Domain Directional Optimization” strategy could serve as a powerful method for developing the isoform-specific fluorescent probe.