title: DNA-binding antibiotics. X-ray structure of the distamycin A analog.
abstract: The crystal structure of the antibiotic distamycin A analog containing two pyrrol carboxamide fragments has been determined. The space group of the crystals is P21/b; the unit-cell dimensions are a = 11.169, b = 21.535, c = 7.863 A, alpha = beta = 90 degrees, gamma = 122.45 degrees, Z = 4. The structure is solved by direct methods, and refined with the full-matrix least-squares procedure. The data on the structure of the pyrrol carboxamide backbone allow the following conclusions to be made about the molecular structure of the distamycin type antibiotics: (i) the amide groups have normal trans-configuration with slightly shortened C-C and C-N bonds adjacent to the pyrrol rings, (ii) the N-methyl groups of the pyrrol rings and the oxygen atoms of the amide groups have the same orientation with respect to the backbone. In the distamycin A analog molecule the pyrrol rings and amide group between them are approximately coplanar.
mesh_terms: D055598:Chemical Phenomena; D002621:Chemistry; D004247:DNA; D004214:Distamycins; D008958:Models, Molecular; D008968:Molecular Conformation; D011758:Pyrroles; D014961:X-Ray Diffraction
chemical_list: D004214:Distamycins; D011758:Pyrroles; D004247:DNA