Crystallization and preliminary X-ray studies of snake gourd lectin: homology with type II ribosome-inactivating proteins

The lectin from the seeds of snake gourd (Trichosanthes anguina) has been c rystallized in two forms using the hanging-drop method. Both the forms are hexagonal, with the asymmetric unit containing one subunit consisting of tw o polypeptide chains linked through disulfide bridges. Intensity data from one of the forms were collected at room temperature as well as at low tempe rature to 3 Angstrom resolution. Molecular-replacement studies indicate tha t the lectin is homologous to type II ribosome-inactivating proteins. Parti al refinement confirms this conclusion.