CRYSTALLIZATION AND PRELIMINARY-X-RAY DIFFRACTION STUDIES ON A RECOMBINANT ISOPENICILLIN N-SYNTHASE FROM CEPHALOSPORIUM-ACREMONIUM

Recombinant isopenicillin N synthase from Cephalosporium acremonium wa s expressed in Escherichia coli and the protein nas purified. After ne arly 5000 crystallization trials, the apo enzyme mas crystallized by t he hanging drop vapour diffusion technique, using polyethylene glycol and lithium sulphate as precipitants. Two crystal forms have been obta ined with either octahedral or elongated prismatic habits. The larger octahedral crystals (0.1 mm over-all dimensions) belong to space group I4 with unit cell dimensions of a = b = 124.7 Angstrom, c 156.9 Angst rom, and diffract X-rays to about 3.5 K resolution at synchrotrons. Th e crystallographic asymmetric unit contains a dimer.