A novel enzymatic assay for the identification of 4-hydroxyphenylpyruvate dioxygenase modulators

4-hydroxyphenylpyruvate dioxygenase (HPPD) is a key enzyme involved in the pathogenesis of tyrosinemia III and cancer. Herein, we describe a spectroscopy-based assay to detect HPPD dioxygenase activity in the presence or absence of small-molecule modulators. We describe steps for transformation, expression, and purification of HPPD and preparation of the assay plate. We detail initiation and completion of the enzymatic reaction followed by detection of remaining substrate in the form of enol-HPP/borate complex. This assay is applicable for high-throughput screening. For complete details on the use and execution of this protocol, please refer to Parkins et al.¹.