Purification, crystallization and preliminary X-ray diffraction results of human 17β-hydroxysteroid dehydrogenase type 5

17β-Hydroxysteroid dehydrogenases (17β-HSDs) catalyze the last step in the biosynthesis of all androgens and estrogens, thus playing a pivotal role in sex-hormone metabolism. Human 17β-HSD type 5 (17β-HSD5) catalyzes hydride transfer at the 17β-hydroxy position, but possesses high sequence homology to 3α-hydroxysteroid dehydrogenases (3α-HSD). Two crystal forms of 17β-HSD5 in an enzyme–testosterone–NADP ternary complex have been obtained under different crystallization conditions. A form I crystal obtained at pH 8.5 diffracted to 1.32 Å. It belonged to space group P2₁, with unit-cell parameters a = 47.41, b = 77.16, c = 48.67 Å, β = 116.32°. Form II crystals obtained at pH 6.5 diffracted to 2.0 Å and belonged to space group P6₃, with unit-cell parameters a = b = 110.58, c = 56.89 Å.