格拉姆柱花草(Stylosanthes gracilis H.B.K.cv.Graham)凝集素的纯化与性质研究

为了探讨凝集素在豆科植物与根瘤菌的识别过程中的作用，用ＤＥＡＥ－３２离子交换层析和ＳｅｐｈａｄｅｘＧ－１５０凝胶过滤分离、纯化格拉姆柱花草种子凝集素（ＳＧＬ），其分子量约为４５ｋＤ，由两个相同的亚基组成，等电点约ｐＨ５．８，它是一种糖蛋白，含糖量约为２．６％．ＳＧＬ的热稳定性强．ＳＧＬ的血凝活性能被甘露糖所抑制．ＳＧＬ对红细胞的凝集作用可能具有种属专一性；ＳＧＬ具有强的促有丝分裂作用；荧光标记实验显示：９株能与格拉姆柱花草植株结瘤的菌株有７株能与ＳＧＬ结合，６株不能与之结瘤的菌株，只有１株能与ＳＧＬ结合，这表明不同根瘤菌菌株对ＳＧＬ的结合能力，和它们在格拉姆柱花草上结瘤能力之间可能具有一定的生物学相关性．

Purification and Characterization of Lectin from Stylosanthes gracilis seed

The possible role of lectin on the recognition between legume and rhizobium was discussed.The Stylosanthes gracilis lectin(SGL) has been extracted with ammonium sulfate and purified by chromatography on DEAE 32 column and gel filtration on Sephadex G 150 SGL exhibits one single band of molecular weight about 24 kD on SDS PAGE,while SGL's molecular weight is 45 kD estimated by gel filtration.It indicates that the lectin molecular contains two identical subunits.The pI of SGL is about 5 8 by isoelectric focusing.SGL is a glycoprotein and has sugar content of 2 6% SGL can agglutinate with the rabbit erythrocytes strongly,but it cannot agglutinate with human erythrocytes(A,B,AB or O type).D manose is just the sugar which can combine with SGL specifically and inhibit agglutination.SGL is an strong mitogen.The transformation ratio of human peripheral blood lymphocytes is 71 7% and the cell division ratio is 12 1%.SGL is labeled with fluorescein isothiocyanate(FITC) by the method of dialyze,and the product FITC SGL is used to treat 15 rhizobium strains.The result shows that FITC SGL can combine specifically with 7 of the 9 strains that nodulated Stylosanthes gracilis and only 1 of the 6 strains that unnodulated Stylosanthes gracilis .It means that there is a positive biological correlation between lectin binding capacity and nodulating ability.