Endoglycosidase H

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The enzyme Endoglycosidase H (Endo-β-N-acetylglucosaminidase H, (EC 3.2.1.96) is a highly specific endoglycosidase which cleaves asparagine-linked mannose rich oligosaccharides, but not highly processed complex oligosaccharides from glycoproteins. Endoglycosidase H cleaves the bond between two N-acetylglucosamine (GlcNAc) subunits directly proximal to the asparagine residue. ^[1]

[edit] Biochemical Applications

Endoglycosidase H (Endo H) is commonly used by cell biologists to monitor posttranslational modification in the Golgi apparatus. Most proteins destined for the cell surface are transcribed by ribosomes in the rough endoplasmic reticulum (ER) and translocated into the Golgi. Upon entering the ER a molecule containing 11 sugar subunits is linked en bloc to an asparagine in a selective manner by the enzyme oligosaccharyl transferase. It is this oligosaccharide molecule which is modified by a series of enzymes as the protein moves through the different compartments of the Golgi apparatus. Endoglycosidase H is able to cleave each structure of this oligosaccharide as it is processed until the enzyme Golgi alpha-mannosidase II removes two mannose subunits. Since all later oligosaccharide structures are resistant to Endo H cleavage the enzyme is widely used to report the extent of oligosaccharide processing a protein of interest has undergone. ^[2]