Wei C H, Koh C
J Biol Chem. 1978 Mar 25;253(6):2061-6.
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.
从蓖麻种子中提取的一种毒性凝集素——蓖麻毒素D，已被纯化并结晶成适合高分辨率晶体结构研究的形式。这种蛋白质与之前发现的一种蓖麻毒素（也存在于同一批种子中）不同，后者是迄今为止唯一一种已报道有初步X射线研究结果的蓖麻毒素。蓖麻毒素D从水溶液中结晶形成空间群为P2(1)2(1)2(1)的正交晶胞，a = 79.0 Å，b = 114.7 Å，c = 72.8 Å。不对称单元包含一个平均分子量为62,400的分子。该晶体对X射线相当稳定，含水量约为54%（体积）。它似乎由两种密切相关的蛋白质组成，主要的一种对应蓖麻毒素D，另一种可能对应蓖麻毒素D的脱酰胺产物。这两种蛋白质分子大小和氨基酸组成几乎相同，但电荷不同。
