Crystalline ricin D, a toxic anti-tumor lectin from seeds of Ricinus communis.
A toxic lectin, ricin D, present in the seeds of Ricinus communis has been purified and crystallized in a form suitable for high resolution crystallographic structure studies. This protein is different from a previously found form of ricin (also present in the same seeds), the only ricin for which a preliminary x-ray investigation has been reported so far. Ricin D crystallizes from an aqueous solution in an orthorhombic unit cell of symmetry P2(1)2(1)2(1) and a = 79.0, b = 114.7, and c = 72.8 A. The asymmetric unit contains one molecule with an average molecular weight of 62,400. The crystal is fairly stable to x-radiation and has a water content of approximately 54% by volume. It appears to comprise two closely related species of proteins, the major species corresponding to recin D and the other presumably corresponding to a deamidation product of ricin D. The two species have nearly identical molecular size and amino acid compositions, but different charges.
D000596:Amino Acids / Q000032:analysis; D000970:Antineoplastic Agents; D037121:Plant Lectins; D010947:Plants, Toxic; D011487:Protein Conformation; D012276:Ricin / Q000302:isolation & purification; D012278:Ricinus / Q000032:analysis*; D012639:Seeds / Q000032:analysis; D014961:X-Ray Diffraction
D000596:Amino Acids; D000970:Antineoplastic Agents; D037121:Plant Lectins; D012276:Ricin