ACCEPTOR SPECIFICITY OF GDP-FUC-GAL-BETA-1-]4GLCNAC-R ALPHA-3-FUCOSYL-TRANSFERASE-VI (FUCT-VI) EXPRESSED IN INSECT CELLS AS SOLUBLE, SECRETED ENZYME

As an extension of a previous study (de Vries et nl,, 1995, J, Biol. C hern., 270, 8712-8722) the acceptor specificity of recombinant FucT VI , expressed in insect cells as soluble enzyme, and purified from the g rowth medium by affinity chromatography, was analyzed toward a broad p anel of oligosaccharide and glycoprotein substrates. It was found that FucT VI effectively utilizes any type-2-chain based structure (Gal be ta 1-->4GlcNAc-R), Neutral as well as sialylated structures are fucosy lated with high efficiency, To identify polar groups on accepters that function in enzyme binding, deoxygenated substrate analogs were teste d as accepters, FucT VI had an absolute requirement for a hydroxyl at C-6 of galactose in addition to the accepting hydroxyl at C-3, Thus, F ucT VI, although different from FucT III, TV, and V in acceptor proper ties, seems to bind the acceptor in a similar way.