FUNCTIONAL PURIFICATION AND CHARACTERIZATION OF A GDP-FUCOSE - BETA-N-ACETYLGLUCOSAMINE (FUC TO ASN LINKED GLCNAC) ALPHA-1,3-FUCOSYL-TRANSFERASE FROM MUNG BEANS

An alpha 1,3-fucosyltransferase was purified 3000-fold from mung bean seedlings by chromatography on DE 52 cellulose and Affigel Blue, by ch romatofocusing, gelfiltration and affinity chromatography resulting in an apparently homogenous protein of about 65 kDa on SDS-PAGE. The enz yme transferred fucose from GDP-fucose to the Asn-linked N-acetylgluco saminyl residue of an N-glycan, forming an alpha 1,3-linkage. The enzy me acted upon N-glycopeptides and related oligosaccharides with the gl ycan structure GlcNAc(2)Man(3) GlcNAc(2). Fucose in alpha 1,6-linkage to the asparagine-linked GlcNAc had no effect on the activity. No tran sfer to N-glycans was observed when the terminal GlcNAc residues were either absent or substituted with galactose. N-acetyllactosamine, lact o-N-biose and N-acetylchito-oligosaccharides did not function as accep tors for the alpha 1,3-fucosyltransferase. The transferase exhibited m aximal activity at pH 7.0 and a strict requirement for Mn2+ or Zn2+ io ns. The enzyme's activity was moderately increased in the presence of Triton X-100. It was not affected by N-ethylmaleimide.