Binding of synthetic sulfated ligands by human splenic galectin 1, a β-galactoside-binding lectin

The carbohydrate-binding site of galectin 1, a vertebrate beta-galactoside-binding lectin, has a pronounced specificity for the beta Gal(1 --> 3)- and beta Gal(1 --> 4)GlcNAc sequences. The binding inhibition study reported herein was carried out to determine whether sulfation of saccharides would influence their binding by galectin 1. The presence of 6'-OSO3- on LacNAc greatly reduces the inhibitory potency relative to LacNAc. 3'-OSO3-LacNAc, 3'-OSO3-Gal beta(1 --> 3)GlcNAc beta 1-OBzl and 3-OSO3-Gal beta 1-OMe are more potent inhibitors than the non-sulfated parent compounds. Surprisingly, 2'-OSO3-LacNAc showed over 40 fold less inhibitory potency relative to LacNAc. Ovarian carcinoma A121 cells were shown to synthesize sulfated macromolecules that bind to galectin 1. Modulation in vivo of saccharide sulfation may lead to modulation of galectin 1 interaction with glycoconjugates; hence, sulfation could play a role in modulating lectin functions.