| Abstract: | A membrane-bound alpha-L-fucosyltransferase, which is involved in the synthesis of a developmentally regulated carbohydrate antigen, SSEA-1, was purified about 2000-fold from F9 embryonal carcinoma cells. The procedures used were solubilization with Triton X-100, column chromatography on SP-Sephadex, DEAE-Sephadex, RCA-agarose and on GDP-agarose. Upon sodium dodecyl sulfate gel electrophoresis, the purified preparation gave a protein band with a relative molecular mass of 65 000. The optimum pH of the enzyme was between 6.0 and 7.0 and the Km toward N-acetyllactosamine was 0.55 mM. The enzyme was active with asialofetuin, but not with intact fetuin. Susceptibility of the product to alpha-L-fucosidase I from almond emulsin verified that the enzyme transferred fucose to C-3 hydroxyl of N-acetylglucosamine in the N-acetyllactosamine structure. Activities of beta-galactoside alpha 1----2-fucosyltransferase and N-acetylglucosaminide alpha 1----4-fucosyltransferase acting on synthetic substrates were not detected in the purified enzyme nor in the crude extract of F9 cells. PYS-2 parietal endoderm cells lacked all the fucosyltransferases mentioned above. |
