Inhibitory effects of glycopolymers having globotriose and/or lactose on cytotoxicity of Shiga toxin 1

Glycopolymers having globotriose and/or lactose were synthesized and evaluated for the inhibitory effects on cytotoxicity of Shiga toxins (Stxs; Stx1 and Stx2). Results showed that glycopolymers having globotriose units exhibited inhibitory effect on cytotoxicity of Stx1 while glycopolymers having small amount of acrylamide exhibited inhibitory effect on cytotoxicity of Stx2. Surprisingly, the glycopolymer having lactose showed inhibitory effect on cytotoxicity of Stx1. The binding of the glycopolymers to Stx1 was also investigated by using BIAcore system. The results showed that the glycopolymer having lactose, which is not known as ligand of Stxs, binds to Stx1. Therefore, Stx1 also recognized the internal residues (Galβ(1–4)Glcβ) of Gb3 (Galα(1–4)Galβ(1–4)Glcβ-ceramide) by composing a cluster. This result suggests that the cluster of the carbohydrates, which have very weak binding affinity for the receptor, can interact with the receptor.