Enzymic Properties of an N‐Acetylglucosaminide 3‐α‐l‐Fucosyltransferase of a Wheat‐Germ Agglutinin‐Resistant Melanoma Clone

Abstract

A fucosyltransferase was solubilized by extraction with Triton CF-54 from a wheat-germ agglutinin-resistant variant of mouse B16 melanoma. Through affinity chromatography on GDPhexanolamine[P''-(6-amino-1-hexyl)-P2-(5''-guanosine)pyrophosphate]-Sepharose a 44-fold enrichment of its specific activity was obtained. Analysis of its specificity indicated that the enzyme is an N-acetylglucosaminide 3-.alpha.-L-fucosyltransferase, which is able to transfer fucose to oligosaccharides containing Gal(.beta.1-4)GlcNAc and Gal(.beta.1-4)Glc [N-acetyllactosamine and lactose, respectively] structures. The enzyme is activated by divalent cations and has a maximum of activity at pH 5. It is unable to transfer fucose to sialylated glycoproteins, 6-.alpha.-sialyllactose or 3-.alpha.-sialyllactose. As suggested by its precipitation in the presence of antibodies raised in rabbit against a soluble human milk N-acetylglucosaminide 3-.alpha.-L-fucosyltransferase, these 2 enzymes seem to be structurally related.