원문정보
초록
영어
Poly-N-acetyllactosamine (poly-LacNAc, (3Gal1-4GlcNAc1-)n) is a linear carbohydrate polymer composed by repeatingN-acetylglucosamine (GlcNAc) and galactose (Gal) residues. These polysaccharides are found either on N- / O-linked glycoproteins or glycolipids and involve in diverse cellular functions such as differentiation, apoptosis, and metastasis. Poly-LacNAc can be further modified by various glycosyltransferases to create branched structures and display terminal epitopes. Sialylated and fucosylated derivatives of poly-LacNAc have been characterized as specific ligands for different lectins such as selectins and galectins as well as being tumor-associated antigens.It is demanded to have various lengths of oligo-LacNAc for studying LacNAc associated biology. However, the traditional organic synthesis requires tedious multiple protection and de-protection steps which are heavily relied on labor-intensive and time-consuming synthetic routes. To efficiently and quickly produce oligo-LacNAc, we expressed the recombinant bacterial enzymes, □ - 1,3-N-acetyl-glucosaminyltransferase of Helicobacter pylori (HpGnT) and □ -1,4-galactosyltransferase of Neisseria meningitides (NmGalT), from E. coli. Defined lengths of oligo-LacNAcs were synthesized by using the expressed enzymes in the presence of sugar donors, uridine 5’-diphosphate galactose (UDP- Gal) and uridine 5’-diphosphate N-acetylglucosamine (UDP-GlcNAc). To reduce the cost of NDP-sugars used in the oligo-LacNAc synthesis, we set up an enzymatic system for one-pot synthesis of NDP- sugars by using a wild-type bacterial thymidylyltransferase (RmlA). In this study, we applied RmlA to synthesize both UDP-Gal and UDP-GlcNAc. In combination with the use of corresponding kinases, UDP- GlcNAc and UDP-Gal were obtained from cheap starting materials, GlcNAc and Gal. Take the advantage of the great thermal stability of RmlA, the sugar nucleotides were prepared with quantitative yield at 55 oC within two hours. By the alternative addition of HpGnT and NmGalT, different lengths of oligo-LacNAc were synthesized. Compare to previous report, we successfully achieve the synthesis of oligo-LacNAc with a more economical way.