A novel plant α4-fucosyltransferase (Vaccinium myrtillus L.) synthesises the Lewisa adhesion determinant

We have partially characterised an alpha4-fucosyltransferase (alpha4-FucT) from Vaccinium myrtillus, which catalysed the biosynthesis of the Lewis(a) adhesion determinant, The enzyme was stable up to 50 degreesC, The optimum pH was 7.01 both in the presence and in the absence of Mn2+. The enzyme was inhibited by Mn2+ and Co2+, and stowed resistance towards inhibition with N-ethylmaleimide. It transferred fucose to N-acetylglucosamine in the type I Gal beta 3GlcNAc motif from oligosaccharides linked to a hydrophobic tail and glycoproteins (containing the type I motif), Sialylated oligosaccharides containing the type II Gal beta 4GlcNAc motif were not accepters. The catalytic mechanism of the plant alpha4-FucT possibly involves a His residue, and it must have arisen by convergent evolution relative to its mammalian counterparts. (C) 2001 Federation of European Biochemical Societies. Published by Elsevier Science B.V. All rights reserved.