3HG3

Human alpha-galactosidase catalytic mechanism 2. Substrate bound

Summary for 3HG3

• Entry DOI: 10.2210/pdb3hg3/pdb
• Related: 1R46 1R47 3HG2 3HG4 3HG5
• Related PRD ID: PRD_900037
• Descriptor: Alpha-galactosidase A, alpha-D-mannopyranose-(1-3)-beta-D-mannopyranose-(1-4)-2-acetamido-2-deoxy-beta-D-glucopyranose-(1-4)-2-acetamido-2-deoxy-beta-D-glucopyranose, 2-acetamido-2-deoxy-beta-D-glucopyranose-(1-4)-2-acetamido-2-deoxy-beta-D-glucopyranose, ... (7 entities in total)
• Functional Keywords: glycoprotein, carbohydrate-binding protein, glycosidase, lysosomal enzyme, (beta/alpha)8 barrel, disease mutation, disulfide bond, hydrolase, lysosome
• Biological source: Homo sapiens (human)
• Total number of polymer chains: 2
• Total formula weight: 97701.24

Authors

Guce, A.I.,Clark, N.E.,Garman, S.C. (deposition date: 2009-05-13, release date: 2009-11-24, Last modification date: 2024-11-27)

Primary citation

Guce, A.I.,Clark, N.E.,Salgado, E.N.,Ivanen, D.R.,Kulminskaya, A.A.,Brumer, H.,Garman, S.C.
Catalytic mechanism of human alpha-galactosidase.
J.Biol.Chem., 285:3625-3632, 2010

PubMed Abstract: The enzyme alpha-galactosidase (alpha-GAL, also known as alpha-GAL A; E.C. 3.2.1.22) is responsible for the breakdown of alpha-galactosides in the lysosome. Defects in human alpha-GAL lead to the development of Fabry disease, a lysosomal storage disorder characterized by the buildup of alpha-galactosylated substrates in the tissues. alpha-GAL is an active target of clinical research: there are currently two treatment options for Fabry disease, recombinant enzyme replacement therapy (approved in the United States in 2003) and pharmacological chaperone therapy (currently in clinical trials). Previously, we have reported the structure of human alpha-GAL, which revealed the overall structure of the enzyme and established the locations of hundreds of mutations that lead to the development of Fabry disease. Here, we describe the catalytic mechanism of the enzyme derived from x-ray crystal structures of each of the four stages of the double displacement reaction mechanism. Use of a difluoro-alpha-galactopyranoside allowed trapping of a covalent intermediate. The ensemble of structures reveals distortion of the ligand into a (1)S(3) skew (or twist) boat conformation in the middle of the reaction cycle. The high resolution structures of each step in the catalytic cycle will allow for improved drug design efforts on alpha-GAL and other glycoside hydrolase family 27 enzymes by developing ligands that specifically target different states of the catalytic cycle. Additionally, the structures revealed a second ligand-binding site suitable for targeting by novel pharmacological chaperones.

PubMed: 19940122
DOI: 10.1074/jbc.M109.060145

Experimental method

X-RAY DIFFRACTION (1.9 Å)