Functional purification and characterization of a GDP-fucose: β-N-acetylglucosamine (Fuc to Asn linked GlcNAc) α1,3-fucosyltransferase from mung beans

Abstract

An α1,3-fucosyltransferase was purified 3000-fold from mung bean seedlings by chromatography on DE 52 cellulose and Affigel Blue, by chromatofocusing, gelfiltration and affinity chromatography resulting in an apparently homogenous protein of about 65 kDa on SDS-PAGE. The enzyme transferred fucose from GDP-fucose to the Asn-linkedN-acetylglucosaminyl residue of an N-glycan, forming an α1,3-linkage. The enzyme acted upon N-glycopeptides and related oligosaccharides with the glycan structure GlcNAc₂Man₃ GlcNAc₂. Fucose in α1,6-linkage to the asparagine-linked GlcNAc had no effect on the activity. No transfer to N-glycans was observed when the terminal GlcNAc residues were either absent or substituted with galactose.N-acetyllactosamine, lacto-N-biose andN-acetylchito-oligosaccharides did not function as acceptors for the α1,3-fucosyltransferase.

The transferase exhibited maximal activity at pH 7.0 and a strict requirement for Mn²⁺ or Zn²⁺ ions. The enzyme's activity was moderately increased in the presence of Triton X-100. It was not affected byN-ethylmaleimide.