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| | {{STRUCTURE_1oim| PDB=1oim | SCENE= }} | | {{STRUCTURE_1oim| PDB=1oim | SCENE= }} |
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| - | '''FAMILY 1 B-GLUCOSIDASE FROM THERMOTOGA MARITIMA'''
| + | ===FAMILY 1 B-GLUCOSIDASE FROM THERMOTOGA MARITIMA=== |
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| - | ==Overview==
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| - | 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 (Bulow, 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.
| + | The line below this paragraph, {{ABSTRACT_PUBMED_14624580}}, adds the Publication Abstract to the page |
| | + | (as it appears on PubMed at http://www.pubmed.gov), where 14624580 is the PubMed ID number. |
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| | + | {{ABSTRACT_PUBMED_14624580}} |
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| | ==About this Structure== | | ==About this Structure== |
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| | [[Category: Glucoside hydrolysis]] | | [[Category: Glucoside hydrolysis]] |
| | [[Category: Hydrolase]] | | [[Category: Hydrolase]] |
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 03:53:38 2008'' | + | |
| | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Tue Jul 29 12:18:36 2008'' |
Revision as of 09:18, 29 July 2008
Template:STRUCTURE 1oim
FAMILY 1 B-GLUCOSIDASE FROM THERMOTOGA MARITIMA
Template:ABSTRACT PUBMED 14624580
About this Structure
1OIM is a Single protein structure of sequence from Thermotoga maritima. Full crystallographic information is available from OCA.
Reference
Iminosugar glycosidase inhibitors: structural and thermodynamic dissection of the binding of isofagomine and 1-deoxynojirimycin to beta-glucosidases., Zechel DL, Boraston AB, Gloster T, Boraston CM, Macdonald JM, Tilbrook DM, Stick RV, Davies GJ, J Am Chem Soc. 2003 Nov 26;125(47):14313-23. PMID:14624580
Page seeded by OCA on Tue Jul 29 12:18:36 2008
