Psathyrella velutina Mushroom Lectin Exhibits High Affinity toward Sialoglycoproteins Possessing Terminal N-Acetylneuraminic Acid 2,3-Linked to Penultimate Galactose Residues of Trisialyl N-Glycans

A lectin from the fruiting body of the Psathyrella velutina mushroom (PVL) was found to bind specifically to N-acetylneuraminic acid, as well as to GlcNAc (Ueda, H., Kojima, K., Saitoh, T., and Ogawa, H. (1999) FEBS Lett. 448, 75–80). In this study, the glycan sequences that PVL recognizes with high affinity on sialoglycoproteins were revealed. Among sialic acid-specific lectins only PVL could reveal the sialylated N-acetyllactosamine structure of glycoproteins in blotting studies, based on the dual specificity. The affinity of PVL to fetuin was measured by surface plasmon resonance to be 10 M , which is an order of magnitude higher than those of Sambucus nigra agglutinin and Maackia amurensis mitogen, whereas affinity to asialofetuin was 0 and to asialoagalactofetuin was 10 M , suggesting that PVL exhibits remarkably high affinities toward glycoproteins possessing trisialoor GlcNAc-exposed glycans. Transferrin was separated into fractions that correspond to the sialylation states on an immobilized PVL column. Transferrin-possessing trisialoglycans containing 2,3-linked N-acetylneuraminic acid on the 1,4-linked GlcNAc branch bound to the PVL column and eluted with GlcNAc; those containing only 2,6-linked sialic acids were retarded, whereas other transferrin fractions passed through the column. These results indicate that PVL is a lectin with potential for separation and detection of sialoglycoproteins because of its dual specificity toward sialoglycans and GlcNAc exposed glycans.