Crystallization and preliminary X-ray diffraction studies of C-1027-AG, the apoprotein of the macromolecular antitumor antibiotic C-1027 from Streptomyces globisporus

C-1027-AG, the apoprotein of the macromolecular antitumor antibiotic C- 1027, isolated from Streptomyces globisporus, was crystallized by the vapor-diffusion procedure using 2-methyl-2,4-pentanediol as a precipitant. The crystals belong to the orthorhombic system, space group P2₁2₁2₁, with unit-cell dimensions a = 55.1, b = 61.3 and c = 79.1 Å. Assuming that the asymmetric unit contains two or three molecules, the V_m value is calculated as 3.2 or 2.1 Å³ Da^-1, respectively. A total of 7630 independent reflections was obtained up to 2.5 Å resolution with synchrotron radiation, the merging R factor being 0.077 for 24 713 measurements.