AUTHOR=Ooi Kai-Eng , Zhang Xiu-Wen , Kuo Cheng-Yu , Liu Ying-Jia , Yu Ching-Ching 

TITLE=Chemoenzymatic Synthesis of Asymmetrically Branched Human Milk Oligosaccharide Lacto-N-Hexaose

JOURNAL=Frontiers in Chemistry

VOLUME=10

YEAR=2022

URL=https://www.frontiersin.org/journals/chemistry/articles/10.3389/fchem.2022.905105

DOI=10.3389/fchem.2022.905105

ISSN=2296-2646

ABSTRACT=<p>We herein reported the first chemoenzymatic synthesis of lacto-<italic>N</italic>-hexaose (LNH) by combining chemical carbohydrate synthesis with a selectively enzymatic glycosylation strategy. A tetrasaccharide core structure GlcNH<sub>2</sub>β1→3 (GlcNAcβ1→6) Galβ1→4Glc, a key precursor for subsequent enzymatic glycan extension toward asymmetrically branched human milk oligosaccharides, was synthesized in this work. When the order of galactosyltransferase-catalyzed reactions was appropriately arranged, the β1,4-galactosyl and β1,3-galactosyl moieties could be sequentially assembled on the C6-arm and C3-arm of the tetrasaccharide, respectively, to achieve an efficient LNH synthesis. Lacto-<italic>N</italic>-neotetraose (LN<italic>n</italic>H), another common human milk oligosaccharide, was also synthesized en route to the target LNH.</p>