Expression and purification of active human 17ß-Hydroxysteroid dehydrogenase type 1 from Escherichia coli.

ABSTRACT

Breast cancer cell growth is often dependent on the presence of steroidal hormones. The 17ß-hydroxysteroid dehydrogenase type 1 isoform (17ßHSD1) catalyzes NADPH-dependent conversion of estrone to estradiol, a more potent estrogen, and represents potential drug target for breast cancer treatment.  To provide active enzyme for inhibitor screening, 17ßHSD1 is usually expressed in insect or mammalian cells, or isolated from human placenta. In the present study we describe a simple protocol for expression and purification of active human 17ßHSD1 from BL21(DE3) Escherichia coli cells. Soluble human 17ßHSD1 was expressed using a pET28a(+)-based plasmid, which encodes a hexahistidine tag fused to the N-terminus of the protein, and purified by nickel affinity chromatography. The enzyme activity of purified 17ßHSD1 was verified by three methods: thin-layer chromatography, an alkali assay and a spectroscopic assay. These non-radioactive enzyme assays require only standard laboratory equipment, and can be used for screening compounds that modulate 17ßHSD1 activity.