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 precipi tant. The crystals belong to the orthorhombic system, space group P2(1 )2(1)2(1), with unit-cell dimensions a=55.1, b=61.3 and c=79.1 angstro m. Assuming that the asymmetric unit contains two or three molecules, the V(m) value is calculated as 3.2 or 2.1 angstrom3 Da-1, respectivel y. A total of 7630 independent reflections was obtained up to 2.5 angs trom resolution with synchrotron radiation, the merging R factor being 0.077 for 24713 measurements.