transglycosylases

Transglycosylases are enzymes that catalyze the transfer of a glycosyl group from a donor molecule to an acceptor, resulting in the formation of a new glycosidic bond. They are defined by their role in creating rather than hydrolyzing glycosidic linkages, though some enzymes can catalyze transglycosylation and hydrolysis under different conditions. The term covers several different enzyme activities across biology.

Mechanistically, transglycosylases show diversity. Some operate by a double-displacement mechanism that generates a covalent glycosyl-enzyme intermediate (retaining the anomeric configuration), while others use an SN2-like single-displacement mechanism (inverting the configuration). They span glycosyltransferase families and, in some contexts, glycoside hydrolases that catalyze transglycosylation rather than hydrolysis. Substrates include lipid-linked donors such as Lipid II in bacteria, as well as oligosaccharides and polysaccharides.

Biological roles are especially prominent in cell wall biosynthesis and remodeling. In bacteria, the transglycosylase activity of penicillin-binding proteins polymerizes glycan strands during peptidoglycan synthesis. In plants and microorganisms, transglycosylases participate in cell wall remodeling and carbohydrate biosynthesis, including starch-related processes. The enzymes are also studied for their ability to modify polysaccharide structures and to synthesize defined oligosaccharides for research or industrial use.

Because many bacterial transglycosylases are essential for cell wall integrity, their enzymes are of interest in antibiotic research, and inhibitors that target transglycosylase activity can disrupt growth. The term remains an umbrella for diverse catalytic strategies that move glycosyl units rather than simply cleaving them.