A New Lectin from Meadow Saffron (Colchicum automnale).

A lectin has been isolated from tubers of the meadow saffron (Colchicum autumnale). It is an octameric protein (M(r) 100,000) composed of 4A- and 4B-subunits of M(r) 15,000 and 10,000, respectively. It is a glycoprotein with 4.4% carbohydrate, the main sugars are (N-acetyl-) glucosamine, mannose, fucose, and xylose. Although the Colchicum autumnale agglutinin (CAA) agglutinates human red blood cells, it has a much higher activity with rabbit erythrocytes. With respect to its carbohydrate-binding specificity CAA behaves rather unusually as it is inhibited by lactose, galactose, N-acetylgalactosamine and related sugars when assayed with human red blood cells but not in assays with rabbit erythrocytes.