Crystal structure of alpha-galactosidase from Trichoderma reesei and its complex with galactose: implications for catalytic mechanism.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.
(2004) J.Mol.Biol. 339: 413-422
- PubMed: 15136043
- DOI: 10.1016/j.jmb.2004.03.062
- Primary Citation of Related Structures:
- PubMed Abstract:
- Crystallization of alpha-galactosidase from Trichoderma reesei.
Golubev, A.M.,Neustroev, K.N.
(1993) J.Mol.Biol. 231: 933
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 s ...
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.
Petersburg Nuclear Physics Institute, Gatchina, St Petersburg, 188300, Russia.