Identification of a GDP-Fuc:Galβ1–3GalNAc-R (Fuc to Gal)α1–2 fucosyltransferase and a GDP-Fuc:Galβ1–4GlcNAc (Fuc to GlcNAc)α1–3 fucosyltransferase in connective tissue of the snailLymnaea stagnalis

Abstract

Connective tissue of the freshwater pulmonateLymnaea stagnalis was shown to contain fucosyltransferase activity capable of transferring fucose from GDP-Fuc in α1–2 linkage to terminal Gal of type 3 (Galβ1–3GalNAc) acceptors, and in α1–3 linkage to GlcNAc of type 2 (Galβ1–4GlcNAc) acceptors. The α1–2 fucosyltransferase was active with Galβ1–3GalNAcβ1-OCH₂CH=CH₂ (K _m=12 mM,V _max=1.3 mU ml⁻¹) and Galβ1–3GalNAc (K _m=20 mM,V _max=2.1 mU ml⁻¹), whereas the α1–3 fucosyltransferase was active with Galβ1–4GlcNAc (K _m=23 mM,V _max=1.1 mU ml⁻¹). The products formed from Galβ1–3GalNAcβ1-OCH₂CH=CH₂ and Galβ1–4GlcNAc were purified by high performance liquid chromatography, and identified by 500 MHz¹H-NMR spectroscopy and methylation analysis to be Fucα1–2Galβ1–3GalNAcβ1-OCH₂CH=CH₂ and Galβ1–4(Fucα1–3)GlcNAc, respectively. Competition experiments suggest that the two fucosyltransferase activities are due to two distinct enzymes.