Chemo-enzymatic synthesis of functionalized oligomers of N-acetyllactosamine glycan derivatives and their immobilization on biomaterial surfaces

Abstract

► Six novel functionalized β- d -GlcNAc derivatives as acceptor substrate of human β1,4 galactosyltransferase 1. ► Step-wise and one-pot enzymatic synthesis of poly- N -acetyllactosamine (poly-LacNAc) oligomers by combination of glycosyltransferases. ► Immobilization of poly-LacNAc oligomers as ligands of the fungal lectin CGL2. Poly- N -acetyllactosamines (poly-LacNAc, [−3Gal(β1–4)GlcNAc(β1−] n ) are terminal glycan structures present in glycoproteins and glycolipids. Their biological functions as ligands for galectins and as carriers of glycan epitopes are well documented. In the present paper we have characterized six novel functionalized β- d -GlcNAc derivatives, including aglyca of varying hydrophobicity and molecular weight, as substrates for recombinant human β1,4 galactosyltransferase 1 (β4GalT-1). The sugar derivatives carry short or long amino- or azide-terminated linker molecules for further modification or immobilization. The linker chemistry had an impact on enzyme kinetics and enzymatic syntheses of N -acetyllactosamine derivatives (LacNAc, Gal(β1–4)GlcNAc(β1-R). The combination of β4GalT-1 with bacterial β1,3- N -acetylglucosaminyltransferase (β3GlcNAc-T) resulted in the preparative syntheses of LacNAc oligomers with up to three LacNAc repeating units. All products were characterized by NMR and MS. The obtained LacNAc glycans were immobilized onto microtiter plates and their efficiency of binding of fungal galectin CGL2 was determined.