In enzymology, a lipopolysaccharide N-acetylglucosaminyltransferase (EC 2.4.1.56) is an enzyme that catalyzes the chemical reaction

UDP-N-acetyl-D-glucosamine + lipopolysaccharide ${\displaystyle \rightleftharpoons }$ UDP + N-acetyl-D-glucosaminyllipopolysaccharide

Thus, the two substrates of this enzyme are UDP-N-acetyl-D-glucosamine and lipopolysaccharide, whereas its two products are UDP and N-acetyl-D-glucosaminyllipopolysaccharide.

This enzyme participates in lipopolysaccharide biosynthesis and glycan structures - biosynthesis 2.

This enzyme belongs to the family of glycosyltransferases, specifically the hexosyltransferases. The systematic name of this enzyme class is UDP-N-acetyl-D-glucosamine:lipopolysaccharide N-acetyl-D-glucosaminyltransferase. Other names in common use include UDP-N-acetylglucosamine-lipopolysaccharide, N-acetylglucosaminyltransferase, uridine diphosphoacetylglucosamine-lipopolysaccharide, and acetylglucosaminyltransferase.

• Osborn MJ, D'Ari L (August 1964). "Enzymatic incorporation of N-acetylglucosamine into cell wall lipopolysaccharide in a mutant strain of Salmonella typhimurium". Biochemical and Biophysical Research Communications. 16 (6): 568–75. doi:10.1016/0006-291X(64)90194-9. PMID 5332855.