An N-acetylglucosamine oligomer binding agglutinin (lectin) from ripe Cyphomandra betacea Sendt. fruits.

A new agglutinin (lectin), called CBL3, was purified from the juice of ripe Cyphomandra betacea Sendt. fruits until electrophoretically pure to homogeneity. The lectin is a homodimer of M(r)=50800 with subunits of 26200 bound by disulfide linkages with a pI of 4.9. The agglutinating capacity of the lectin is only inhibited by oligomers of N-acetylglucosamine in the following order of potency: tetrasaccharide>trisaccharide>disaccharide. CBL3 is not inhibited by N-acetylglucosamine, the same as all known lectins of the Solanaceae family. The human blood group recognition is non-specific. The lectin is a glycoprotein with 13.6% (w/w) of carbohydrates. The agglutinating activity is not affected by EDTA nor by cations. Mitogenic activity was not detected. Heat and pH stability, amino acid composition, N-terminal amino acid sequence and immunological properties show substantial differences to the reported lectins isolated from the Solanaceae family.