1OIM

Family 1 b-glucosidase from Thermotoga maritima

Summary for 1OIM

• Entry DOI: 10.2210/pdb1oim/pdb
• Related: 1OD0 1OIF 1OIN
• Descriptor: BETA-GLUCOSIDASE A, 1-DEOXYNOJIRIMYCIN (3 entities in total)
• Functional Keywords: hydrolase, glucoside hydrolysis, family gh1, enzyme, deoxynojirimycin
• Biological source: THERMOTOGA MARITIMA
• Total number of polymer chains: 2
• Total formula weight: 108207.64

Authors

Gloster, T.,Zechel, D.L.,Boraston, A.B.,Boraston, C.M.,Macdonald, J.M.,Tilbrook, D.M.,Stick, R.V.,Davies, G.J. (deposition date: 2003-06-19, release date: 2003-11-25, Last modification date: 2023-12-13)

Primary citation

Zechel, D.L.,Boraston, A.B.,Gloster, T.,Boraston, C.M.,Macdonald, J.M.,Tilbrook, D.M.,Stick, R.V.,Davies, G.J.
Iminosugar Glycosidase Inhibitors: Structural and Thermodynamic Dissection of the Binding of Isofagomine and 1-Deoxynojirimycin to Beta-Glucosidases
J.Am.Chem.Soc., 125:14313-, 2003

PubMed Abstract: The design and synthesis of transition-state mimics reflects the growing need both to understand enzymatic catalysis and to influence strategies for therapeutic intervention. Iminosugars are among the most potent inhibitors of glycosidases. Here, the binding of 1-deoxynojirimycin and (+)-isofagomine to the "family GH-1" beta-glucosidase of Thermotoga maritima is investigated by kinetic analysis, isothermal titration calorimetry, and X-ray crystallography. The binding of both of these iminosugar inhibitors is driven by a large and favorable enthalpy. The greater inhibitory power of isofagomine, relative to 1-deoxynojirimycin, however, resides in its significantly more favorable entropy; indeed the differing thermodynamic signatures of these inhibitors are further highlighted by the markedly different heat capacity values for binding. The pH dependence of catalysis and of inhibition suggests that the inhibitory species are protonated inhibitors bound to enzymes whose acid/base and nucleophile are ionized, while calorimetry indicates that one proton is released from the enzyme upon binding at the pH optimum of catalysis (pH 5.8). Given that these results contradict earlier proposals that the binding of racemic isofagomine to sweet almond beta-glucosidase was entropically driven (Bülow, A. et al. J. Am. Chem. Soc. 2000, 122, 8567-8568), we reinvestigated the binding of 1-deoxynojirimycin and isofagomine to the sweet almond enzyme. Calorimetry confirms that the binding of isofagomine to sweet almond beta-glucosidases is, as observed for the T. maritima enzyme, driven by a large favorable enthalpy. The crystallographic structures of the native T. maritima beta-glucosidase, and its complexes with isofagomine and 1-deoxynojirimycin, all at approximately 2.1 A resolution, reveal that additional ordering of bound solvent may present an entropic penalty to 1-deoxynojirimycin binding that does not penalize isofagomine.

PubMed: 14624580
DOI: 10.1021/JA036833H

Experimental method

X-RAY DIFFRACTION (2.15 Å)