Synthesis and characterization of a novel glycopolymer with protective activity toward human anti-α-Gal antibodies

An efficient and rapid synthesis of the derivative of the biocompatible polymer poly(styrene co-maleic acid) with Linear B disaccharide (Galili antigen) was achieved. The oligosaccharide portion was obtained by a transglycosylation reaction catalyzed by coffee bean alpha-D-galactosidase using p-nitrophenyl-alpha-D-galactopyranoside both as donor and as acceptor. The reaction was carried out in aqueous buffer without any organic cosolvent. The molar yield (30%) and the regioselectivity (82%) were significantly improved with respect to the data so far reported in the literature. The selective reduction of the p-nitrophenyl group afforded the p-aminophenyl derivative of Linear B disaccharide. Linkage of this derivative via an amidic bond to the poly(styrene co-maleic acid) was obtained by using N'-(3-dimethylaminopropyl)-N-ethylcarbodiimide hydrochloride and N-hydroxysuccinimide. The products were chemically characterized by ionspray mass spectrometry, infrared, C-13- and H-1-nuclear magnetic resonance. The glycopolymer specifically reacts with human serum containing antibodies and with a mixture of partially purified human IgG and IgM anti-Linear B. It efficiently protects pig kidney PK15 cells from cytotoxic effects of human serum.