Human microsomal prostaglandin E synthase-1 (mPGES-1) is a membrane associated protein that catalyzes the conversion of prostaglandin $H_2$ ($PGH_2$) into prostaglandin $E_2$ ($PGE_2$). In this study, the expression of human mPGES-1 in E. coli was significantly enhanced by modifying the utility of specific codons and the recombinant mPGES-1 was efficiently purified to homogeneity. The $K_m$ and $V_{max}$ of the purified enzyme were determined and the trimeric state characterized by chemical cross-linking with glutaraldehyde. The purified mPGES-1 was used for the screening of a chemical library of bioactive or drug compounds to identify novel inhibitors, and oxacillin and dyphylline were identified as moderately inhibiting mPGES-1 with $I_{C50}$ values of 100 and 200 ${mu}M$, respectively. As these compounds competitively inhibited the catalysis of $PGH_2$, their binding sites appeared to be located near the $PGH_2$ binding pocket.