Crystallization and Preliminary X-ray Diffraction Analysis of the Complex of Human Placental 17β-Hydroxysteroid Dehydrogenase with NADP

Single crystals of human placental 17β-hydroxysteroid dehydrogenase, an enzyme that plays an important role in the interconversion of estrogens, were obtained as the NADP + complex. These are the first crystals suitable for complete X-ray structure analysis ever reported for a steroid-converting enzyme from a human source. The crystals were grown by vapor diffusion at pH 7·5 with polyethyleneglycol (4000) as the precipitating agent. They have a monoclinic space group C2 and unit cell parameters are a = 123·03 Å, b = 45·03 Å, c = 61·29 Å, and β = 99·1°. A complete set of diffraction data to 2·9 Å has been collected on native crystals.