Biosynthesis in vitro of SA-Lex and SA-diLex by alpha 1-3 fucosyltransferases from colon carcinoma cells and embryonic brain tissues.
The sialyl-fucosyl-lactosamine-epitope present in sialyl (SA)-Lex (NeuAc alpha 2-3Gal beta 1-4 [Fuc alpha 1-3]GlcNAc beta 1-3Gal beta 1-4Glc-Cer), a carcinoembryonic antigen, has been recognized recently as a ligand for the binding of leukocyte-endothelial cell adhesion molecule 1 (LECAM-1) to myeloid and tumour cell surfaces. We have recently detected the presence of an alpha 1-3 fucosyltransferase (FucT-3) activity in both embryonic chicken brain (ECB) and human colon carcinoma cells (Colo-205) which catalyses the biosynthesis in vitro of SA-Lex and SA-diLex. Fucosyltransferase activities from both sources are stimulated in the presence of divalent cations (Mn2+, Mg2+, Ca2+, Co2+ and Fe2+), although absolute metal requirement is not observed. Substrate specificity studies with this partially purified (ECB, 3000-fold; Colo-205, 100-fold) novel FucT-3 indicate the preference for terminally sialyl-substituted glycolipid acceptors, as observed by the lower Km values when sialyl-neolactotetraosyl ceramide, LM1, (Neu-Gc alpha 2-3Gal beta 1-4GlcNAc beta 1-3Gal beta 1-4 Glc-Cer; Km = 0.048 mM) and sialyl-norhexaosylceramide, NeuGc-nLc6, (Neu-Gc alpha 2-3Gal beta 1-4 GlcNAc beta 1-3Gal beta 1-4GlcNAc beta 1-3Gal beta 1-4Glc-Cer; Km = 0.032 mM) were used as substrates. Fucosyltransferase from Colo-205 requires the presence of the acyl group of the ceramide moiety and an acetyl group on glucosamine in the acceptor glycolipid since lyso-LM1 was found to be completely inactive.(ABSTRACT TRUNCATED AT 250 WORDS)
Basu
M
M
Department of Chemistry and Biochemistry, University of Notre Dame, IN 46556.
Hawes
J W
JW
Li
Z
Z
Ghosh
S
S
Khan
F A
FA
Zhang
B J
BJ
Basu
S
S
D000818:Animals; D000911:Antibodies, Monoclonal; D001921:Brain / Q000196:embryology / Q000201:enzymology*; D002236:Carbohydrate Conformation; D002240:Carbohydrate Sequence; D002272:Carcinoembryonic Antigen / Q000096:biosynthesis / Q000737:chemistry; D002460:Cell Line; D002642:Chick Embryo; D002846:Chromatography, Affinity; D003110:Colonic Neoplasms / Q000201:enzymology*; D004797:Enzyme-Linked Immunosorbent Assay; D000939:Epitopes / Q000032:analysis; D005647:Fucosyltransferases / Q000302:isolation & purification / Q000378:metabolism*; D006801:Humans; D007124:Immunoenzyme Techniques; D007700:Kinetics; D016256:Lewis X Antigen / Q000096:biosynthesis*; D008969:Molecular Sequence Data; D013379:Substrate Specificity
D000911:Antibodies, Monoclonal; D002272:Carcinoembryonic Antigen; D000939:Epitopes; D016256:Lewis X Antigen; C069719:sialosyl dimeric Le(x) antigen; D005647:Fucosyltransferases; C031692:galactoside 3-fucosyltransferase