In enzymology, a dolichyl-diphosphooligosaccharide–protein glycotransferase is an enzyme that catalyzes the chemical reaction dolichyl diphosphooligosaccharide + protein L-asparagine ⇌ {\displaystyle \rightleftharpoons } dolichyl diphosphate + a glycoprotein with the oligosaccharide chain attached by N-glycosyl linkage to protein L-asparagineThus, the two substrates of this enzyme are dolichyl diphosphooligosaccharide and protein L-asparagine, whereas its 3 products are dolichyl diphosphate, glycoprotein with the oligosaccharide chain attached by N-glycosyl, and linkage to protein L-asparagine. Wikipedia