Characterization of SARS‐CoV main protease and identification of biologically active small molecule inhibitors using a continuous fluorescence‐based assay

Abstract
Severe acute respiratory syndrome associated coronavirus main protease (SARS‐CoV Mpro) has been proposed as a prime target for anti‐SARS drug development. We have cloned and overexpressed the SARS‐CoV Mpro in Escherichia coli, and purified the recombinant Mpro to homogeneity. The kinetic parameters of the recombinant SARS‐CoV Mpro were characterized by high performance liquid chromatography‐based assay and continuous fluorescence‐based assay. Two novel small molecule inhibitors of the SARS‐CoV Mpro were identified by high‐throughput screening using an internally quenched fluorogenic substrate. The identified inhibitors have K i values at low μM range with comparable anti‐SARS‐CoV activity in cell‐based assays.