Construction and structural characterization of versatile lactosaminoglycan-related compound library for the synthesis of complex glycopeptides and glycosphingolipids

We have established a facile and efficient protocol for the preparative-scale synthesis of various compound libraries related to lactosaminoglycans:  cell surface oligosaccharides composed of N-acetyllactosamine as a repeating disaccharide unit, based on chemical and enzymatic approaches. Substrate specificity and feasibility of a bacterial glycosyltransferase, Neisseria meningitidis β1,3-N-acetylglucosaminyltransferase (LgtA), were investigated in order to synthesize various key intermediates suited for the construction of mammalian O-glycopeptides and glycosphingolipids containing poly-N-acetyllactosamine structures. Recombinant LgtA exhibited the highest glycosyltransferase activity with strongly basic conditions (pH = 10, glycine−NaOH buffer) and a broad range of optimal temperatures from 20 to 30 °C. Interestingly, it was found that LgtA discriminates l-serine and l-threonine and functions both as a core-1 β1,3-N-acetylglucosaminyltransferase and core-2 β1,3-N-acetylglucosaminyltransferase toward Fmo...