CRYSTAL-STRUCTURE OF THE PEANUT LECTIN - T-ANTIGEN COMPLEX - CARBOHYDRATE SPECIFICITY GENERATED BY WATER BRIDGES

Peanut lectin binds with high specificity to the tumour-associated dis accharide Gal beta 1-3GalNAc, generally known as T-antigen, The crysta l structure of the complex of the lectin with the disaccharide has bee n determined at 2.5 Angstrom resolution. Comparison of the structure w ith that of the corresponding complex with lactose reveals that the sp ecificity of the lectin for T-antigen is generated primarily by two sp ecific water-mediated interactions, probably the first instance where water-bridges have been demonstrated to be responsible for generating specificity in protein-carbohydrate interactions. The elucidation of t he structure of peanut lectin-T-antigen complex also provides a framew ork for exploring peanut lectin-based prognosis and diagnosis of certa in types of carcinoma.