IDENTIFICATION OF A GDP-FUC-GAL-BETA-1-3GALNAC-R (FUC TO GAL) ALPHA-1-2 FUCOSYL-TRANSFERASE AND A GDP-FUC-GAL-BETA-1-4GLCNAC (FUC TO GLCNAC) ALPHA-1-3 FUCOSYL-TRANSFERASE IN CONNECTIVE-TISSUE OF THE SNAIL LYMNAEA-STAGNALIS

Connective tissue of the freshwater pulmonate Lymnaea stagnalis was sh own to contain fucosyltransferase activity capable of transferring fuc ose from GDP-Fuc in alpha 1-2 linkage to terminal Gal of type 3 (Gal b eta 1-3GalNAc) accepters, and in alpha 1-3 linkage to GlcNAc of type 2 (Gal beta 1-4GlcNAc) accepters. The alpha 1-2 fucosyltransferase was active with Gal beta 1-3GalNAc beta 1-OCH2CH=CH2 (K-m = 12 mM, V-max = 1.3 mU ml(-1)) and Gal beta 1-3GalNAc (K-m = 20 mM, V-max = 2.1 mU ml (-1)), whereas the alpha 1-3 fucosyltransferase was active with Gal be ta 1-4GlcNAc (K-m = 23 mM, V-max = 1.1 mU ml(-1)). The products formed from Gal beta 1-3GalNAc beta 1-OCH2CH=CH2 and Gal beta 1-4GlcNAc were purified by high performance liquid chromatography, and identified by 500 MHz H-1-NMR spectroscopy and methylation analysis to be Fuc alpha 1-2Gal beta 1-3GalNAc beta 1-OCH2CH=CH2 and Gal beta 1-4(Fuc alpha 1- 3)GlcNAc, respectively. Competition experiments suggest that the two f ucosyltransferase activities are due to two distinct enzymes.