Catalyzes the attachment of L-vancosamine to a monoglucosylated heptapeptide intermediate during the final stage of glycopeptide antibiotic vancomycin biosynthesis. devancoaminyl-vancomycin + dTDP-beta-L-vancosamine = dTDP + H(+) + vancomycin kcat is 67.6 min (-1). Antibiotic biosynthesis; vancomycin biosynthesis. In A.orientalis different glycosyltransferases are involved in biosynthesis of the vancomycin group of antibiotics. GtfA (AC P96558), GtfB (AC P96559) and GtfC (AC P96560) are involved in biosynthesis of antibiotic chloroeremomycin, while GtfD and GtfE (AC G4V4R9) are involved in biosynthesis of vancomycin. Belongs to the glycosyltransferase 28 family.