The three-dimensional structure of a Trichoderma reesei beta-mannanase from glycoside hydrolase family 5

The crystal structure of the catalytic core domain of beta-mannanase from t he fungus Trichoderma reesei has been determined at a resolution of 1.5 Ang strom. The structure was solved using the anomalous scattering from a singl e non-isomorphous platinum complex with two heavy-metal sites in space grou p P2(1). The map computed with the experimental phases was enhanced by the application of an automated model building and refinement procedure using t he amplitudes and experimental phases as observations. This approach is exp ected to be of more general application. The structure of the native enzyme and complexes with Tris-HCl and mannobiose are also reported: the mannobio se binds in subsites +1 and +2. The structure is briefly compared with that of the homologous beta-mannanase from the bacterium Thermomonospora fusca.