The amino acid sequence of toxin V from Anemonia sulcata

Preparations of the β-galactoside-binding lectin of bovine heart have been shown to stimulate $\text{in vitro}$ the sialylation of the oligosaccharide Ga1β1→4G1cNAc and asialo-α₁-acid glycoprotein by bovine colostrum β-D-galactoside α2→6 sialyltransferase. Kinetic data revealed that in the presence of lectin the K_m values for Ga1β1→4G1cNAc and CMP-NeuAc were reduced from 25.0 to 11.6 mM and from 0.42 to 0.19 mM respectively, but the K_m for asialo-α₁-acid glycoprotein and the V_max values for all three substrates were little affected. Stimulation by the lectin was partially inhibited by Fucα1→2Ga1β1→4G1cNAc. This, together with the effects of certain plant lectins, suggests that the stimulation of sialytransferase may be mediated through the carbohydrate-binding properties of the lectin.