1SZN

THE STRUCTURE OF ALPHA-GALACTOSIDASE

Summary for 1SZN

• Entry DOI: 10.2210/pdb1szn/pdb
• Descriptor: alpha-galactosidase, 2-acetamido-2-deoxy-beta-D-glucopyranose-(1-4)-2-acetamido-2-deoxy-beta-D-glucopyranose, alpha-D-mannopyranose-(1-3)-alpha-D-mannopyranose-(1-3)-[alpha-D-mannopyranose-(1-3)-alpha-D-mannopyranose-(1-6)]beta-D-mannopyranose-(1-4)-2-acetamido-2-deoxy-beta-D-glucopyranose-(1-4)-2-acetamido-2-deoxy-beta-D-glucopyranose, ... (6 entities in total)
• Functional Keywords: (beta/alpha)8 barrel, two domains, glycoprotein, hydrolase
• Biological source: Hypocrea jecorina
• Total number of polymer chains: 1
• Total formula weight: 48951.92

Authors

Golubev, A.M.,Nagem, R.A.P.,Brando Neto, J.R.,Neustroev, K.N.,Eneyskaya, E.V.,Kulminskaya, A.A.,Shabalin, K.A.,Savel'ev, A.N.,Polikarpov, I. (deposition date: 2004-04-06, release date: 2004-08-10, Last modification date: 2024-10-16)

Primary citation

Golubev, A.M.,Nagem, R.A.P.,Neustroev, K.N.,Eneyskaya, E.V.,Kulminskaya, A.A.,Shabalin, K.A.,Savel'ev, A.N.,Polikarpov, I.
Crystal structure of alpha-galactosidase from Trichoderma reesei and its complex with galactose: implications for catalytic mechanism.
J.Mol.Biol., 339:413-422, 2004

PubMed Abstract: The crystal structures of alpha-galactosidase from the mesophilic fungus Trichoderma reesei and its complex with the competitive inhibitor, beta-d-galactose, have been determined at 1.54 A and 2.0 A resolution, respectively. The alpha-galactosidase structure was solved by the quick cryo-soaking method using a single Cs derivative. The refined crystallographic model of the alpha-galactosidase consists of two domains, an N-terminal catalytic domain of the (beta/alpha)8 barrel topology and a C-terminal domain which is formed by an antiparallel beta-structure. The protein contains four N-glycosylation sites located in the catalytic domain. Some of the oligosaccharides were found to participate in inter-domain contacts. The galactose molecule binds to the active site pocket located in the center of the barrel of the catalytic domain. Analysis of the alpha-galactosidase- galactose complex reveals the residues of the active site and offers a structural basis for identification of the putative mechanism of the enzymatic reaction. The structure of the alpha-galactosidase closely resembles those of the glycoside hydrolase family 27. The conservation of two catalytic Asp residues, identified for this family, is consistent with a double-displacement reaction mechanism for the alpha-galactosidase. Modeling of possible substrates into the active site reveals specific hydrogen bonds and hydrophobic interactions that could explain peculiarities of the enzyme kinetics.

PubMed: 15136043
DOI: 10.1016/j.jmb.2004.03.062

Experimental method

X-RAY DIFFRACTION (1.54 Å)