Vasconcelos I M, Trentim A, Guimarães J A, Carlini C R
Department Biochemistry and Molecular Biology, Universidade Federal do Ceará, Fortaleza, Brazil.
Arch Biochem Biophys. 1994 Aug 1;312(2):357-66. doi: 10.1006/abbi.1994.1320.
Physicochemical characterization and biological properties of a new toxic protein isolated from soybeans (Glycine max) is reported. The purification procedure consisted basically of ammonium sulfate fractionation, ion exchange, and affinity chromatographies, the latter being used for the removal of the seed's lectin and of its trypsin inhibitor. The highly purified protein, designated soyatoxin, is a single chain acidic protein (pI 4.4-4.6) of 21 kDa, dependent on reduced thiol groups to maintain its solubility and biological activities. The toxin is a metalloprotein containing iron, calcium, zinc, and magnesium. Soyatoxin is highly toxic to mice (LD50 7-8 mg/kg mouse body wt upon intraperitoneal injection). It produces dyspnoea, tonic-clonic convulsions, and flaccid paralysis prior to death of intraperitoneally injected mice. Furthermore, soyatoxin is immunologically related to another toxic protein (canatoxin), isolated from Canavalia ensiformis seeds, which is distinct from soyatoxin in containing 18 x 10 kDa noncovalently bound subunits. Some biological properties including acute intraperitoneal toxicity, canatoxin-like immunoreactivity, hemagglutination, trypsin inhibitory activity, induction of platelet release reaction, and aggregation displayed by soyatoxin were studied and used to differentiate soyatoxin from soybean lectin and trypsin inhibitors.
报道了从大豆（Glycine max）中分离出的一种新型有毒蛋白质的物理化学特性和生物学特性。纯化过程主要包括硫酸铵分级分离、离子交换和亲和色谱，后者用于去除种子中的凝集素及其胰蛋白酶抑制剂。高度纯化的蛋白质，命名为大豆毒素，是一种21 kDa的单链酸性蛋白质（pI 4.4 - 4.6），依赖于还原型巯基来维持其溶解性和生物学活性。该毒素是一种含有铁、钙、锌和镁的金属蛋白。大豆毒素对小鼠具有高毒性（腹腔注射时，小鼠半数致死量为7 - 8 mg/kg体重）。它会使腹腔注射的小鼠在死亡前出现呼吸困难、强直性阵挛性惊厥和弛缓性麻痹。此外，大豆毒素与从刀豆（Canavalia ensiformis）种子中分离出的另一种有毒蛋白质（刀豆毒素）存在免疫相关性，刀豆毒素与大豆毒素的不同之处在于它含有18个10 kDa的非共价结合亚基。研究了大豆毒素表现出的一些生物学特性，包括急性腹腔毒性、刀豆毒素样免疫反应性、血凝、胰蛋白酶抑制活性、诱导血小板释放反应和聚集，并用于区分大豆毒素与大豆凝集素和胰蛋白酶抑制剂。
