Specificity analysis of the C-type lectin from rattlesnake venom, and its selectivity towards Gal- or GalNAc-terminated glycoproteins

The rattlesnake ( Crotalus atrox ) venom lectin is a readily-prepared decameric C-type lectin, specific for Gal and GalNAc. Glycan microarray analysis showed it reacted with a wide range of glycans, chiefly recognizing sets of compounds with Galβ1-4GlcNAc (LacNAc), α-Gal or α-GalNAc non-reducing termini. Its array profile was therefore distinctly different from those of four previously studied mammalian C-type lectins with the same Gal/GalNAc monosaccharide specificity, and it was more broadly reactive than several Gal- or GalNAc-specific plant lectins commonly used for glycan blotting. Though a general reactivity towards glycoproteins might be expected from the avidity conferred by its high valence, it showed a marked preference for glycoproteins with multiple glycans, terminated by Gal or GalNAc. Thus its ten closely-spaced sites each with a K D for GalNAc of ~2 mM appeared to make RSVL more selective than the four more widely-spaced sites of soybean agglutinin, with a ten-fold better K D for GalNAc.