Purification and characterization of a lectin from seeds and cotyledonary callus of Zizyphus mauritiana

A lectin from Zizyphus mauritiana lamk. has been purified from the 25-50% (NH4)(2)SO4 fraction of crude seed and cotyledonary leaf callus extracts. The lectins purified from the two sources had the same structure and properties. Upon specific adsorption on Sephadex G-100, the lectin (ZML) could be displaced with 0.1 M D-glucose. ZML yielded a single band corresponding to a M-r of 66 kDa both in the absence and presence of beta-mercaptoethanol on native-as well as in SDS-PAGE. It is thermostable but pH sensitive and agglutinates human erythrocytes only. Lectin activity could also be detected in the cotyledons, leaf, and stem, and in their cultures, as well as in in vitro regenerants. Cotyledons, cotyledonary leaf and its callus showed much higher lectin activity than seeds.