Year: 2002
Type: conference-abstract
Abstract: Endo-β-N-acetylglucosaminidase A (Endo A) is a 72 kDa glycohydrolase that, unlike other endoglycosidases such as Endo H, is capable of transglycosylation: the transfer of released oligosaccharides to hydroxyl groups other than water.The enzyme has been used in the enzymatic synthesis of neoglycoconjugates.The crystal structure of Endo A, in complex with a core pentamannoside, has been determined to 2.2 Å resolution.The molecule consists of three domains: an endoglycosidase domain with typical (β/α) 8fold; a plant lectin-like all-β-domain; and a fibronectin type III domain.The role of the two additional domains is unclear because they are not positioned correctly for interaction with the substrate.The active site of the enzyme differs from that of Endo H and related endoglycosidases in that the primary catalytic residue, Glu173, is in hydrogen bonding contact with Trp216, a residue that has been shown to be essential for transglycosylation.In addition, the aspartic acid that has been shown to be involved in stabilizing the intermediate in the substrate-assisted catalysis mechanism of family-18 glycohydrolases is replaced by an asparagine.The interaction of the pentamannoside with the enzyme reveals that the high-mannose substrate specificity of Endo A is defined by positive recognition of the α(1-3)-linked mannose on the α(1-6)-linked branch.However, the detailed molecular architecture in this area of the molecule differs greatly from that of other highmannose specific endoglycosidases such as Endo H and Endo F1.
Language: English
Subfield: Molecular Biology
Domain: Life Sciences
Open Access status: bronze
Funder: National Institutes of Health
OpenAlex ID: W2022059580