A NEW CRYSTAL FORM OF PHOTOLYASE (PHOTOREACTIVATING ENZYME) FROM THE CYANOBACTERIUM ANACYSTIS-NIDULANS

A new trigonal crystal form of photolyase from the cyanobacterium Anac ystis nidulans has been obtained by the addition of ethylenediaminetet raacetate to the crystallization condition previously used for the tet ragonal crystals. In contrast with the tetragonal form that is grown a s assemblies of small single crystals, isolated large single crystals were obtained for the present trigonal form, thus providing a regular supply of crystals for X-ray diffraction work. The new form of crystal belongs to the space group P3(1)21 or P3(2)21 with unit cell dimensio ns of a = b = 146 Angstrom and c = 134 Angstrom. Assuming that the asy mmetric unit contains two or three molecules, the V-m value is calcula ted as 3.9 or 2.6 Angstrom(3)/Da, respectively. The present crystals d iffract X-ray beyond 3.0 Angstrom resolution with synchrotron radiatio n and were stable toward X-ray exposure. (C) 1995 Academic Press, Inc.