Selectin ligands and tumor-associated carbohydrate structures: specificities of alpha 2,3-sialyltransferases in the assembly of 3'-sialyl-6-sialyl/sulfo Lewis a and x, 3'-sialyl-6'-sulfo Lewis x, and 3'-sialyl-6-sialyl/sulfo blood group T-hapten.

Abstract

The sequence in the assembly of the functional unit of selectin ligands containing sulfate, sialic acid, and fucose and also tumor-associated O-glycan structures was studied by examining the specificities of alpha 2,3-sialyltransferases (ST). The first enzyme, porcine liver ST, was 57, 37, and 79% active (Km: 0.105, 0.420, and 0.200 mM), respectively, toward 6-sulfo, 6-sialyl, or 6-O-methyl derivatives of the Gal beta 1,3GalNAc alpha- unit; C-3 or C-6 substitution on Gal abolished sialylation. An acrylamide copolymer (MW approximately 40,000) containing approximately 40 T-haptens and asialo Cowper's gland mucin (MW approximately 200,000) containing approximately 48 T-haptens was 5-fold more active as an acceptor as compared to Gal beta 1, 3GalNAc alpha-O-Al on a molecular weight basis. The second enzyme, a cloned alpha-2,3-ST specific for lactose-based structure, was 70, 102, and 108% active (Km: 0.500, 0.210, and 0.330 mM), respectively, toward 6-sialyl, 6-sulfo, or 6-O-methyl derivatives of the Gal beta 1,3GlcNAc beta- unit; C-3 and C-6 substitution on Gal abolished sialylation. Gal beta 1,4GlcNAc beta- and its 6-sulfo derivative were approximately 20% active; the Lewis a structure, Gal beta 1,3- (Fuc alpha 1,4)GlcNAc beta-, was not an acceptor. The acrylamide copolymers containing approximately 40 units of Gal beta 1,3GlcNAc beta-, Gal beta 1,3(6-sulfo)GlcNAc beta-, or fetuin triantennary asialo or bovine IgG diantennary glycopeptides were respectively 5.9-, 5.4-, 0.7-, and 0.1-fold as active. A transfer of 7-9 mol of NeuAc per mole of the above copolymers was catalyzed by this ST, the sialyl linkage being susceptible to alpha 2,3-specific sialidase. A partially purified Colo 205 Lewis type (alpha 1, 3/4) fucosyltransferase catalyzed the formation of 3'-sialyl-6-sulfo Lewis a from [9-3H]NeuAc alpha 2, 3Gal beta 1, 3(6-sulfo)GlcNAc beta-O-Allyl and copolymer containing [9-3H]NeuAc alpha 2, 3Gal beta 1, 3(6-sulfo)GlcNAc beta- units, using GDP[14C]Fuc as fucosyl donor. The third enzyme, HL-60 ST, was 103% active with Gal beta 3(6-sulfo)GalNAc alpha- but was only 8% active with 6-sialo compound; it showed 11.6-fold greater activity with the copolymer of T-hapten. Further, we observed the alpha 2,3 sialylation of Gal beta 1,4GlcNAc beta- but not Gal beta 1,3GlcNAc beta- by HL60-ST, consistent with the occurrence of 3'-sialyl LacNAc and 3'-sialyl Lewis x units in leukosialin of HL60.(ABSTRACT TRUNCATED AT 400 WORDS)

• Authors: E V Chandrasekaran, R K Jain, R D Larsen, K Wlasichuk, K L Matta
• Journal: Biochemistry (Biochemistry) Vol. 34 Issue 9 Pg. 2925-36 (Mar 07 1995) ISSN: 0006-2960 [Print] United States
• PMID: 7534477 (Publication Type: Journal Article, Research Support, U.S. Gov't, P.H.S.)

Chemical References

• Antigens, Tumor-Associated, Carbohydrate
• Cell Adhesion Molecules
• Glycoconjugates
• Haptens
• Lewis Blood Group Antigens
• Ligands
• Mucins
• Sialic Acids
• Sulfates
• L-Selectin
• sulfated glycoprotein p50
• Sialyltransferases
• beta-Galactoside alpha-2,3-Sialyltransferase

Topics

• Animals
• Antigens, Tumor-Associated, Carbohydrate (chemistry, metabolism)
• Carbohydrate Sequence
• Cell Adhesion Molecules (metabolism)
• Glycoconjugates (chemistry, metabolism)
• Haptens (chemistry, metabolism)
• Humans
• In Vitro Techniques
• Kinetics
• L-Selectin
• Lewis Blood Group Antigens (chemistry, metabolism)
• Ligands
• Liver (enzymology)
• Molecular Sequence Data
• Mucins (chemistry, metabolism)
• Sialic Acids (chemistry)
• Sialyltransferases (metabolism)
• Substrate Specificity
• Sulfates (chemistry)
• Swine
• beta-Galactoside alpha-2,3-Sialyltransferase